Calcinor Oral Suspension

Mechanism of action

Cyanocobalamin serves as a cofactor for methionine synthase and L-methylmalonyl-CoA mutase enzymes. Methionine synthase is essential for the synthesis of purines and pyrimidines that form DNA. L-methylmalonyl-CoA mutase is involved in the degradation of propionate, crucial for fat and protein metabolism. The lack of vitamin B12 results in the accumulation of methylmalonyl CoA, contributing to neurological manifestations. Additionally, it is vital for the synthesis of methionine from homocysteine, and its deficiency can lead to functional folate deficiency, which impacts red blood cell formation.

Pharmacodynamics

Cyanocobalamin corrects vitamin B12 deficiency and alleviates symptoms and laboratory abnormalities associated with pernicious anemia, such as megaloblastic indices, gastrointestinal lesions, and neurological damage. It is essential for growth, cell reproduction, hematopoiesis, nucleoprotein, and myelin synthesis. The drug significantly impacts fat and carbohydrate metabolism, as well as protein synthesis. Rapidly dividing cells, such as those in the bone marrow, have a high demand for vitamin B12. Parenteral administration of cyanocobalamin can quickly reverse the anemia and gastrointestinal symptoms of vitamin B12 deficiency, while also preventing the progression of related neurological damage.

Pharmacokinetics

Cyanocobalamin is absorbed in the intestine, primarily in the ileum, via specific transport mechanisms that may be impaired in individuals with intrinsic factor deficiency (as seen in pernicious anemia). Once absorbed, it is widely distributed in body tissues, with significant concentrations found in the liver, kidneys, and heart. The vitamin is stored in the liver, where it can be released into circulation as needed. Cyanocobalamin undergoes conversion to its active forms, methylcobalamin and adenosylcobalamin, which are utilized in various metabolic processes. The elimination half-life is variable, but it is generally excreted via urine as metabolites

Adverse effects

• Abdominal distension
• Decreased appetite
• Flatulence
• Nausea

Interactions

• Folic acid may interact with cyanocobalamin, especially in cases of megaloblastic anemia caused by folate deficiency.

Precautions

• Should not be given alone for pernicious anemia.
• Use caution in patients with Leber's disease, as it may worsen optic atrophy.

Pregnancy

Cyanocobalamin is essential during pregnancy as it helps prevent neural tube defects. It is advised that females of childbearing potential take 5 mg of folic acid daily before conception and throughout pregnancy.

Breast-feeding

Cyanocobalamin is generally considered safe during breastfeeding, but it is advised to monitor the infant for any adverse effects.

Storage

Store in a cool, dry place, away from direct sunlight. Protect from moisture.

Formulations

• Tablet: 1000 micrograms
• Tablet: 500 micrograms
• Tablet: 100 micrograms
• Oral solution: 50 micrograms per ml
• Solution for injection: 1000 micrograms per ml

Indications

• Thickening agent in topical formulations
• Anti-caking agent in powders
• Carrier for active pharmaceutical ingredients

Dosage

Children: Refer to specific formulation guidelines in the BNF for Children.

Adults: Refer to specific formulation guidelines in the BNF.

Mechanism of action

Aerosil exerts its effects primarily through its surface characteristics. The interaction of silica particles with biological systems can lead to cytotoxicity and cellular transformation, which are influenced by the distribution of silanol groups and the presence of trace metals such as iron. The cytotoxic effects are related to the ability of silica to generate reactive oxygen species, leading to oxidative stress in cells. The biological response to aerosil is sensitive to the composition and structural features of the silica surface, indicating that its activity is a surface-originated phenomenon.

Pharmacodynamics

The pharmacodynamic properties of aerosil are related to its ability to modify the rheological properties of formulations, improve flowability, and prevent clumping. Its cytotoxic effects at high concentrations can lead to cellular stress and transformation, although these effects are primarily of concern in occupational exposure rather than therapeutic use. The dose-response relationship can vary based on the specific type of silica and its surface modifications.

Pharmacokinetics

Aerosil is not absorbed systemically when used in pharmaceutical formulations due to its high molecular weight and physical properties. Inhalation of silica dust can lead to pulmonary exposure, where it may elicit inflammatory responses and potentially lead to silicosis over prolonged exposure. Its elimination from the body does not occur via typical metabolic pathways; instead, silica particles may be cleared from the lungs by macrophage action and mucociliary clearance mechanisms.

Indications

• Vitamin D deficiency
• Rickets
• Osteomalacia
• Osteoporosis
• Hypoparathyroidism

Dosage

Adults: The usual adult dose for vitamin D deficiency is 800 to 2000 IU daily, depending on the severity of deficiency and clinical condition. Higher doses may be used under medical supervision.

Mechanism of action

Cholecalciferol is converted to its active forms, 25-hydroxyvitamin D in the liver and 1,25-dihydroxyvitamin D in the kidneys. These metabolites enhance the intestinal absorption of calcium and phosphorus, increase serum calcium levels, and mobilize these minerals from bone. This process is regulated by parathyroid hormone, which influences calcium and phosphate metabolism, particularly in the kidneys.

Pharmacodynamics

The pharmacodynamics of cholecalciferol involve its conversion to active metabolites that play a significant role in calcium and phosphorus homeostasis. The metabolites facilitate intestinal absorption of these minerals, promote bone mineralization, and influence renal reabsorption. The onset of action occurs within 10 to 24 hours following administration, as metabolic activation is required for its biological effects.

Pharmacokinetics

Cholecalciferol is absorbed in the gastrointestinal tract, and its absorption is enhanced by the presence of dietary fats. It is transported in the bloodstream bound to vitamin D-binding protein. Once in the liver, it undergoes hydroxylation to form 25-hydroxyvitamin D, which is further converted in the kidneys to the active form, 1,25-dihydroxyvitamin D. The elimination half-life of cholecalciferol varies, typically spanning several days, and it is primarily excreted in bile and urine.

Adverse effects

• Hypercalcemia
• Hypercalciuria
• Nausea
• Vomiting
• Constipation
• Weakness
• Fatigue

Interactions

• May enhance the effects of thiazide diuretics, leading to increased risk of hypercalcemia
• Anticonvulsants may increase metabolism of vitamin D, leading to reduced effectiveness
• Cholestyramine may reduce absorption of vitamin D

Precautions

• Monitor serum calcium levels in patients with renal impairment
• Caution in patients with a history of hypercalcemia or hyperparathyroidism
• Use with caution in patients taking other medications that affect calcium metabolism

Pregnancy

Cholecalciferol can be used during pregnancy if indicated, as vitamin D is essential for fetal bone development.

Breast-feeding

Cholecalciferol is excreted in breast milk, but is generally considered safe during breastfeeding.

Storage

Store in a cool, dry place, away from light. Keep out of reach of children.

Formulations

• Capsules
• Tablets
• Liquid formulations

Indications

• Dehydration
• Hypovolemia
• Electrolyte imbalance
• Fluid resuscitation in shock
• Maintenance fluid therapy

Dosage

Children: Dosage should be determined based on the individual child's condition and specific guidelines. Refer to the BNF for Children for detailed dosing information.

Adults: Dosage varies based on clinical condition and patient needs. Refer to specific clinical guidelines and protocols for detailed dosing information.

Mechanism of action

Crystalloids work primarily by increasing the intravascular volume and improving tissue perfusion. They help restore fluid balance by distributing into the extracellular compartment, effectively replenishing lost fluids and electrolytes. The exact mechanism depends on the specific type of crystalloid solution used, but generally, they contribute to osmotic pressure and fluid movement across cell membranes.

Pharmacodynamics

The pharmacodynamics of crystalloids involve their ability to quickly expand the intravascular volume and maintain blood pressure during hypovolemic states. The effectiveness of crystalloids in volume replacement is influenced by their osmolarity and electrolyte composition. Isotonic crystalloids are particularly effective in treating dehydration and shock, as they mimic the body's extracellular fluid composition.

Pharmacokinetics

Crystalloids are characterized by rapid distribution within the extracellular space after administration. They are distributed throughout the interstitial and intravascular compartments within minutes. The half-life of crystalloids is relatively short, as they are rapidly eliminated from the body, with a significant portion excreted via the kidneys. The duration of action can be brief, often necessitating repeated administration in cases of ongoing fluid loss.

Pregnancy

Consult relevant guidelines as data on safety in pregnancy is limited.

Breast-feeding

Consult relevant guidelines as data on safety during breastfeeding is limited.

Storage

Store in a cool, dry place away from direct sunlight.

Indications

• Food coloring agent
• Pharmaceutical coloring agent
• Diagnostic agent in certain imaging procedures

Dosage

Children: Refer to specific preparations for paediatric dosing as it may vary widely depending on the formulation and intended use.

Adults: Refer to specific preparations for adult dosing as it may vary widely depending on the formulation and intended use.

Mechanism of action

Erythrosine acts as a fluorescent dye, absorbing light in the visible spectrum and emitting it at a different wavelength. It binds to proteins and nucleic acids, which can affect biological processes such as cell division and apoptosis. Erythrosine's mechanism also involves interaction with cellular membranes, potentially influencing membrane integrity and function.

Pharmacodynamics

Erythrosine exhibits properties as a photosensitizer, with its efficacy increasing under light exposure. It can impact cellular activity by generating reactive oxygen species when activated by light, leading to oxidative stress in cells. This mechanism is utilized in certain therapeutic applications, although it is primarily recognized for its colorant properties.

Pharmacokinetics

Erythrosine is absorbed from the gastrointestinal tract when ingested, with peak plasma concentrations occurring shortly after administration. It is distributed throughout the body and is known to cross biological membranes. The compound is primarily excreted via urine, with some metabolites detected, indicating hepatic metabolism. The elimination half-life of erythrosine is variable and influenced by individual physiology and dosage.

Contra-indications

• Hypersensitivity to erythrosine or any of its components
• Thyroid disorders
• Patients with iodine allergy

Adverse effects

• Hypersensitivity reactions
• Thyroid dysfunction
• Nausea
• Vomiting
• Diarrhea
• Skin rashes

Interactions

• May interact with thyroid function tests, leading to false results
• Potential for interactions with other iodine-containing compounds

Precautions

• Use with caution in patients with a history of thyroid disease
• Monitor thyroid function in patients receiving long-term therapy
• Assess for allergic reactions prior to administration

Pregnancy

Erythrosine should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. Consult healthcare professional for advice.

Breast-feeding

It is not known whether erythrosine is excreted in human milk. Use with caution, considering the benefits and risks.

Storage

Store in a cool, dry place away from light. Keep out of reach of children.

Formulations

• Oral suspension
• Injectable solution

Indications

• Severe infections caused by gram-negative bacteria
• Complicated urinary tract infections
• Bacterial sepsis
• Endocarditis caused by susceptible organisms

Dosage

Children: Dosing in children is also weight-based and varies by indication. Refer to the BNF for Children for specific dosing recommendations.

Adults: Dosage varies significantly based on the infection severity and type, renal function, and the specific bacterial susceptibility. Refer to clinical guidelines or the BNF for precise dosing.

Mechanism of action

Gram works by inhibiting bacterial protein synthesis. It binds to the 30S ribosomal subunit of the bacteria, causing misreading of the mRNA and ultimately preventing the synthesis of essential proteins necessary for bacterial growth and replication.

Pharmacodynamics

The pharmacodynamics of Gram include its bactericidal activity against susceptible bacteria. The drug shows concentration-dependent killing, meaning that higher drug concentrations correlate with greater bactericidal effects. The post-antibiotic effect is noted, where bacterial growth is inhibited even after the drug concentration falls below the minimum inhibitory concentration (MIC).

Pharmacokinetics

Gram is usually administered parenterally (intravenously or intramuscularly), and its absorption can vary based on the route of administration. It is distributed widely in body fluids and tissues, although it does not penetrate well into the central nervous system. The drug is primarily eliminated through the kidneys, and its half-life may be prolonged in patients with renal impairment. Monitoring of drug levels may be necessary to avoid toxicity.

Adverse effects

• Nausea
• Vomiting
• Diarrhea
• Abdominal pain
• Allergic reactions
• Rash
• Renal dysfunction

Precautions

• Use with caution in patients with renal impairment
• Monitor renal function during therapy
• Assess for potential allergic reactions

Pregnancy

Use only if the potential benefit justifies the potential risk to the fetus. Consult with a healthcare provider.

Breast-feeding

Use with caution, as it may be excreted in breast milk. Consult with a healthcare provider.

Storage

Store in a cool, dry place away from direct sunlight. Keep out of reach of children.

Dosage

Children: Refer to specific guidelines for pediatric dosing; consult the BNF for Children for accurate dosage information.

Adults: Refer to specific guidelines for use; dosage may vary based on the context of use.

Mechanism of action

Hydroxide ions act primarily as bases, neutralizing acids to form water and salts. They participate in various biochemical pathways, including selenium metabolism and the degradation of reactive oxygen species. Hydroxide can influence enzyme activity and stability by altering the pH of the environment, thereby affecting metabolic reactions.

Pharmacodynamics

Hydroxide ions can impact biological processes by changing the local pH, which influences enzyme activity, ion transport, and the solubility of other compounds. Their ability to neutralize acids can help regulate physiological pH, contributing to homeostasis in living organisms.

Pharmacokinetics

As an inorganic ion, hydroxide does not undergo traditional pharmacokinetic processes like absorption, distribution, metabolism, or excretion. Instead, it is rapidly equilibrated in biological fluids and participates in acid-base reactions, having immediate effects on the local environment.

Pregnancy

There is limited information regarding the use of hydroxide during pregnancy. Consult a healthcare professional for advice.

Breast-feeding

Limited data is available on the excretion of hydroxide in breast milk. Consult a healthcare professional before use.

Storage

Store in a cool, dry place away from direct sunlight. Keep out of reach of children.

Dosage

Children: Paediatric fluid requirements should be calculated based on age, weight, and clinical condition. Refer to the guidelines in the BNF for Children for detailed recommendations.

Adults: Dosage in litres may vary depending on clinical circumstances, such as fluid resuscitation needs, maintenance fluid requirements, or medication delivery. Refer to clinical guidelines for specific scenarios.

Mechanism of action

Litres do not have a pharmacological mechanism of action as they are a unit of measurement rather than a drug. However, the administration of fluids measured in litres can influence various physiological processes, including hydration status, electrolyte balance, and overall fluid homeostasis in the body.

Pharmacodynamics

As a measurement unit, litres do not exhibit pharmacodynamics. However, the volume of fluid administered can impact the pharmacodynamics of medications that are diluted or delivered in fluid form, affecting the rate of absorption, distribution, metabolism, and excretion of drugs.

Pharmacokinetics

Litres as a unit of volume do not possess pharmacokinetic properties. The pharmacokinetics of a drug may be influenced by the volume of fluid in which it is administered, as this can affect the concentration of the drug in the bloodstream and its subsequent pharmacological effects.

Indications

• Allergic conditions
• Autoimmune diseases
• Asthma and chronic obstructive pulmonary disease (COPD)
• Certain cancers (e.g., leukemia, lymphoma)
• Skin conditions (e.g., dermatitis)
• Inflammatory bowel disease
• Multiple sclerosis exacerbations
• Severe infections requiring immunosuppression

Dosage

Children: Refer to BNF for Children for specific dosing; doses vary significantly based on the child's age, weight, and condition being treated.

Adults: Refer to BNF for specific dosing; typically, initial doses range from 4 to 48 mg depending on the severity of the condition.

Mechanism of action

Methylprednisolone exerts its effects by binding to glucocorticoid receptors, leading to the modulation of gene expression. This interaction influences the transcription of anti-inflammatory proteins while suppressing the expression of pro-inflammatory genes, ultimately resulting in reduced inflammation and immune response.

Pharmacodynamics

The pharmacodynamic effects of methylprednisolone are characterized by its ability to decrease inflammation, suppress the immune response, and affect carbohydrate metabolism. Therapeutic doses lead to various systemic effects, including modification of leukocyte distribution and inhibition of cytokine production.

Pharmacokinetics

Methylprednisolone is well absorbed after oral administration, with a bioavailability of approximately 50%. It has a volume of distribution that reflects extensive tissue binding. The drug is metabolized primarily in the liver through conjugation and reduction, and its metabolites are excreted in urine. The half-life varies based on the route of administration but is generally around 18 to 36 hours.

Adverse effects

• Increased blood pressure
• Hyperglycemia
• Weight gain
• Mood changes
• Insomnia
• Gastrointestinal disturbances
• Increased susceptibility to infections

Interactions

• methylphenidate+apraclonidine: Severe (decreases effects)
• methylthioninium chloride+bupropion: Severe (increases risk of severe hypertension)
• methylphenidate+linezolid: Severe (increases risk of elevated blood pressure)
• rasagiline+methylphenidate: Severe (increases risk of a hypertensive crisis)
• mao-inhibitors+methylphenidate: Severe (increases risk of a hypertensive crisis)
• dronedarone+methylprednisolone: Moderate (increases exposure)
• miconazole+methylprednisolone: Moderate (increases concentration)
• antifungals, azoles+methylprednisolone: Moderate (increases exposure)
• crizotinib+methylprednisolone: Moderate (increases exposure)

Precautions

• Use with caution in patients with hypertension
• Monitor blood glucose levels in diabetic patients
• Consider potential for infection risk due to immunosuppression
• Evaluate for psychiatric effects in susceptible individuals

Pregnancy

Corticosteroids may be used during pregnancy if the potential benefit justifies the risk to the fetus. Careful monitoring is advised.

Breast-feeding

Corticosteroids are excreted in breast milk; caution is advised. Monitor the infant for potential effects.

Storage

Store in a cool, dry place, away from light. Keep out of reach of children.

Formulations

• Tablets
• Injectable solutions
• Topical preparations

Mechanism of action

Methylsulphate functions as a methylating agent, transferring a methyl group to nucleophiles. This process involves the formation of a sulfonium ion, which is highly reactive and can readily react with nucleophilic sites on various substrates, leading to methylation reactions.

Pharmacodynamics

The pharmacodynamics of methylsulphate is primarily related to its role as a methylating agent in biochemical reactions. It can alter the structure and function of biological molecules, potentially affecting cellular processes and signaling pathways. However, detailed pharmacodynamic studies specific to therapeutic use are limited.

Pharmacokinetics

There is limited information on the pharmacokinetics of methylsulphate, given its typical use as a reagent in laboratory settings rather than a clinical drug. When used in chemical reactions, its reactivity and transformation into other compounds would dictate its pharmacokinetic profile, which could vary significantly based on the specific context of use.

Pregnancy

There is limited data on the use of methylsulphate in pregnancy. Consult relevant guidelines.

Breast-feeding

Data on the excretion of methylsulphate in human milk is not available. Caution is advised.

Storage

Store in a cool, dry place, away from direct sunlight.

Indications

• Preservative in cosmetics
• Preservative in pharmaceuticals
• Preservative in food products

Dosage

Children: Refer to specific product guidelines as dosing varies based on formulation and concentration used.

Adults: Refer to specific product guidelines as dosing varies based on formulation and concentration used.

Mechanism of action

Parabens work by inhibiting the growth of microorganisms through their ability to disrupt the cellular processes of bacteria and fungi. They penetrate the microbial cell membrane and disrupt enzyme and protein functions, leading to cell death. Parabens are known to have low toxicity and are metabolized by the body, subsequently being excreted in urine.

Pharmacodynamics

Parabens demonstrate broad-spectrum antimicrobial activity, making them effective preservatives in various formulations. Their efficacy is influenced by factors such as concentration, pH, and the presence of other ingredients in the formulation. Due to their structural similarity to estrogen, there has been concern regarding their potential endocrine-disrupting effects, although the clinical significance of this is still debated.

Pharmacokinetics

Parabens are readily absorbed through the skin and gastrointestinal tract. Once absorbed, they are rapidly metabolized primarily in the liver. They undergo hydrolysis to form para-hydroxybenzoic acid, which is then conjugated with glucuronic acid and excreted in urine. The half-life of parabens in the human body is relatively short, and they are eliminated rapidly.

Adverse effects

• Allergic reactions, such as skin rashes
• Irritation at the site of application
• Endocrine disruption (in high concentrations)

Precautions

• Use with caution in individuals with known sensitivities or allergies to parabens
• Consider potential endocrine effects with prolonged exposure

Pregnancy

Parabens are generally considered safe in cosmetics and personal care products during pregnancy, although caution is advised due to potential endocrine disruption.

Breast-feeding

Parabens are considered safe in breastfeeding, but it is recommended to use products with minimal or no parabens when possible.

Storage

Store in a cool, dry place away from direct sunlight. Keep out of reach of children.

Formulations

• Topical creams
• Lotions
• Shampoos
• Conditioners
• Makeup products
• Pharmaceutical preparations

Indications

• Hypophosphatemia
• Calcium phosphate deficiency
• Nutritional supplementation
• pH adjustment in pharmaceutical formulations

Dosage

Children: Refer to BNF for Children for specific dosing recommendations based on indication.

Adults: Refer to clinical guidelines or BNF for specific dosing recommendations based on indication.

Mechanism of action

Phosphoric acid provides phosphate ions that are critical for numerous biochemical reactions in the body. These phosphate ions are involved in the formation of ATP, which is essential for energy transfer within cells. The acid itself dissociates in aqueous solutions, releasing hydrogen ions and contributing to pH levels, which can affect enzymatic activities and cellular functions.

Pharmacodynamics

Phosphoric acid acts by replenishing phosphate levels in the body, which can be important in various physiological processes including energy metabolism, bone mineralization, and the synthesis of nucleic acids. Its effects on pH regulation can also influence metabolic pathways, particularly in managing acidosis or alkalosis.

Pharmacokinetics

Phosphoric acid is generally administered orally or intravenously, depending on the therapeutic application. Following administration, it is absorbed in the gastrointestinal tract, with phosphate ions distributed throughout the body. The kidneys play a significant role in regulating phosphate homeostasis, with excess phosphate being excreted in urine. The half-life of phosphoric acid is not well defined, as it is rapidly metabolized and utilized in various metabolic pathways.

Adverse effects

• Nausea
• Vomiting
• Diarrhea
• Abdominal pain
• Hypophosphatemia

Precautions

• Use with caution in patients with renal impairment
• Monitor phosphate levels in patients receiving long-term therapy
• Consider potential for gastrointestinal irritation

Pregnancy

Phosphoric acid is generally considered safe in pregnancy when used in recommended doses, but caution is advised.

Breast-feeding

Phosphoric acid is excreted in breast milk, use with caution and under medical supervision.

Storage

Store at room temperature, away from moisture and heat.

Formulations

• Oral solutions
• Tablets
• Syrups

Indications

• Hypophosphatemia
• Bone disorders (e.g., osteomalacia, rickets)
• Nutritional supplementation in deficiency states

Dosage

Children: Refer to BNF for Children for specific paediatric dosing guidance based on the condition being treated.

Adults: Refer to BNF for specific adult dosing guidance based on the condition being treated.

Mechanism of action

Phosphorus decreases the absorption of intercellular calcified cartilage matrix by osteoclasts in the metaphyseal region of growing bones, leading to increased bone density and thickness, observable as 'phosphorus bands' on radiographs. Additionally, exposure to white phosphorus damages the rough and smooth endoplasmic reticulum, impairing protein synthesis and lipid transport, particularly affecting the synthesis of very low-density lipoproteins (VLDL) and causing hepatic steatosis and fibrosis.

Pharmacodynamics

Phosphorus is involved in bone metabolism and energy transfer within cells. It contributes to the structural framework of bones and teeth, and its role in ATP formation is crucial for energy metabolism. The balance of phosphorus with calcium and vitamin D is essential for maintaining bone health and preventing disorders such as osteomalacia and rickets.

Pharmacokinetics

Phosphorus is absorbed in the gastrointestinal tract, with absorption rates affected by factors such as dietary composition and the presence of other minerals. It is distributed throughout body tissues, particularly in bones and teeth. Phosphorus is primarily excreted through the kidneys, and its serum levels are regulated by hormonal influences, including parathyroid hormone and calcitriol.

Pregnancy

Phosphorus is essential for fetal development; however, excessive intake should be avoided. Consult healthcare professionals for appropriate supplementation.

Breast-feeding

Phosphorus is secreted in breast milk; adequate maternal intake is important for infant health. Consult healthcare professionals for guidance.

Storage

Store in a cool, dry place, away from direct sunlight and moisture. Ensure it is kept out of reach of children.

Indications

• Emulsifying agent in drug formulations
• Stabilizer for parenteral preparations
• Solubilizer for hydrophobic drug compounds
• Ingredient in topical formulations

Dosage

Children: Refer to specific product guidelines, as dosing varies based on formulation and intended use.

Adults: Refer to specific product guidelines, as dosing varies based on formulation and intended use.

Mechanism of action

Polysorbate functions primarily as an emulsifying agent. It reduces the surface tension between immiscible liquids, allowing them to mix more easily. This property is particularly useful in stabilizing emulsions and suspensions, facilitating the delivery of active pharmaceutical ingredients in various formulations.

Pharmacodynamics

Polysorbate does not exert pharmacological effects in the traditional sense, as it does not bind to specific receptors to elicit a physiological response. Instead, it plays a crucial role in modifying the physical properties of drug formulations, thereby enhancing drug delivery and absorption. Its ability to solubilize drugs enhances their bioavailability, particularly for poorly soluble compounds.

Pharmacokinetics

Polysorbate is generally considered to be non-toxic and is not absorbed to a significant extent when administered orally. It is metabolized by the liver and excreted primarily through the gastrointestinal tract. The pharmacokinetic profile may vary depending on the route of administration and the specific formulation in which it is used.

Adverse effects

• Allergic reactions
• Skin irritation
• Gastrointestinal disturbances

Precautions

• Use cautiously in patients with known allergies to polysorbates or related compounds
• Monitor for allergic reactions in susceptible individuals

Pregnancy

Polysorbate is generally considered safe for use during pregnancy, but consult with a healthcare provider for specific cases.

Breast-feeding

Polysorbate is considered safe during breastfeeding, but consult with a healthcare provider for individual advice.

Storage

Store at room temperature, away from direct sunlight and moisture.

Formulations

• Polysorbate 20
• Polysorbate 80

Indications

• Hyperthyroidism
• Graves' disease
• Thyroid storm

Dosage

Children: Refer to the BNF

Adults: The usual initial dose of propylthiouracil in adults is 300 mg per day, divided into 3 doses. The maintenance dose is typically 100-150 mg per day, adjusted based on thyroid function tests.

Mechanism of action

Propylthiouracil acts by inhibiting the enzyme thyroid peroxidase, which is involved in the iodination of tyrosine residues in thyroglobulin, a precursor of thyroid hormones. By blocking this enzyme, PTU reduces the production of thyroxine (T4) and triiodothyronine (T3), leading to decreased thyroid hormone levels in circulation. Additionally, PTU inhibits the conversion of T4 to T3 in peripheral tissues, further contributing to its antithyroid effects.

Pharmacodynamics

The pharmacodynamic effects of propylthiouracil are primarily centered around its ability to lower thyroid hormone levels, which helps alleviate symptoms of hyperthyroidism such as increased heart rate, weight loss, and anxiety. The onset of action can vary, but therapeutic effects may be observed within several weeks of initiation. Monitoring thyroid function tests is essential to assess the efficacy and adjust dosing as needed.

Pharmacokinetics

Propylthiouracil is well absorbed from the gastrointestinal tract, though its bioavailability can be affected by factors such as food intake. The drug is extensively metabolized in the liver, and its elimination half-life averages around 1-2 hours. Most of the drug is excreted in urine as metabolites. It is important to note that due to its rapid metabolism, multiple daily doses may be required to maintain therapeutic levels.

Interactions

• propylthiouracil+metyrapone: Severe (decreases effects)

Dosage

Children: Refer to specific drug formulations and product labels as purified substances can vary widely in their use and dosing.

Adults: Refer to specific drug formulations and product labels as purified substances can vary widely in their use and dosing.

Mechanism of action

The mechanism of action for purified compounds varies widely depending on the specific substance. Generally, purified drugs exert their effects by interacting with specific biological targets, such as receptors, enzymes, or ion channels, leading to a desired therapeutic effect. This interaction can involve binding to receptors to activate or inhibit signaling pathways, modulating enzymatic activity, or altering physiological processes.

Pharmacodynamics

Pharmacodynamics describes the effects of a drug on the body and the relationship between drug concentration and effect. For purified drugs, this can involve dose-response relationships and the time course of their action. The purified form often enhances potency and reduces variability in response among patients, which can lead to more predictable therapeutic outcomes. The overall effect is determined by the drug's affinity for its target, the efficacy of the drug-receptor interaction, and the downstream signaling pathways activated as a result of this interaction.

Pharmacokinetics

Pharmacokinetics involves the absorption, distribution, metabolism, and excretion (ADME) of a drug. For purified substances, absorption can be more efficient due to the absence of impurities that may affect solubility or stability. Distribution may also be enhanced, leading to higher bioavailability. Metabolism can be influenced by the structure of the purified compound, as it may be metabolized more readily by liver enzymes. Excretion typically occurs through the kidneys or liver, depending on the molecular characteristics of the purified drug.

Pregnancy

Consult with a healthcare professional, as the safety of purified forms of medications during pregnancy may vary depending on the specific substance.

Breast-feeding

Consult with a healthcare professional, as the safety of purified forms of medications during breastfeeding may vary depending on the specific substance.

Storage

Store in a cool, dry place, away from light and moisture, and keep out of reach of children.

Indications

• Constipation
• Diagnostic aid in colonoscopy preparation
• Management of hyperosmolality in various conditions

Dosage

Children: For children, the dosage should be determined based on age and condition, and it is advised to refer to the BNF for Children for specific dosing guidelines.

Adults: The typical dose for adults is 30 to 150 mL of sorbitol solution (70%) taken orally, as needed, usually before bedtime.

Mechanism of action

Sorbitol exerts its laxative effect by drawing water into the large intestine, thereby stimulating bowel movements. It acts as a hygroscopic agent, pulling water from tissues into the feces, which reflexively stimulates evacuation. In metabolic pathways, sorbitol is produced from glucose via aldose reductase and is converted to fructose by sorbitol dehydrogenase, with implications in diabetic complications such as retinopathy.

Pharmacodynamics

Sorbitol's laxative effect results from its osmotic properties, which increase the water content of the stool and soften it, facilitating easier passage. Additionally, sorbitol can induce apoptosis in certain cancer cell lines, indicating potential therapeutic implications beyond its laxative use. The modulation of intracellular signaling pathways through the regulation of proteins such as Bax and Bcl-2 suggests a complex role in cellular health and disease.

Pharmacokinetics

Sorbitol is poorly absorbed in the gastrointestinal tract, which contributes to its efficacy as a laxative. It is metabolized in the liver, primarily through the polyol pathway. The absorption and distribution of sorbitol are affected by its osmotic properties, leading to increased intestinal water retention. Its elimination is primarily via renal excretion, with minimal systemic absorption, thus reducing the risk of systemic side effects.

Adverse effects

• Diarrhea
• Abdominal cramps
• Nausea
• Vomiting
• Electrolyte imbalances

Precautions

• Use with caution in patients with renal impairment
• May exacerbate gastrointestinal conditions

Pregnancy

Sorbitol is generally considered safe during pregnancy, but should be used under medical supervision.

Breast-feeding

Sorbitol is excreted in breast milk in small amounts; consult a healthcare provider before use.

Storage

Store in a cool, dry place, away from direct sunlight.

Formulations

• Oral solution
• Syrup

Indications

• Magnetic resonance imaging (MRI) contrast enhancement
• Drug delivery systems
• Potential therapeutic applications in oncology

Dosage

Children: Refer to the BNF for Children for appropriate pediatric dosing information.

Adults: Refer to the specific guidelines for dosage as per BNF and clinical protocols.

Mechanism of action

The principal uptake mechanism for superparamagnetic iron oxide nanoparticles involves clathrin-mediated endocytosis that is dependent on scavenger receptor A. This process allows phagocytic cells, particularly macrophages, to internalize the nanoparticles effectively. The interaction of these nanoparticles with macrophages is critical for their application in imaging and potential therapeutic interventions.

Pharmacodynamics

Superparamagnetic iron oxide nanoparticles exhibit properties that enhance the visibility of tissues during imaging procedures. Their magnetic properties allow for a significant increase in contrast during MRI scans. Additionally, they may have implications in therapeutic contexts, such as in the targeting of cancer cells, where their uptake by macrophages could facilitate localized drug delivery.

Pharmacokinetics

The pharmacokinetics of superparamagnetic iron oxide nanoparticles are characterized by rapid uptake by phagocytic cells, particularly in the liver and spleen. Following systemic administration, these nanoparticles are primarily cleared by macrophages through endocytosis. The particles tend to accumulate in the reticuloendothelial system, which can influence their distribution and elimination from the body.

Pregnancy

There is limited data on the safety of iron oxide nanoparticles during pregnancy. Caution is advised.

Breast-feeding

Limited data is available regarding the excretion of iron oxide nanoparticles in breast milk. Caution is advised.

Storage

Store in a cool, dry place away from light. Keep out of reach of children.

Formulations

• Carboxydextran-coated superparamagnetic iron oxide nanoparticles

Indications

• Rheumatoid arthritis
• Atopic dermatitis
• Psoriatic arthritis
• Ulcerative colitis

Dosage

Children: Refer to the BNF for Children for dosing information in pediatric patients.

Adults: Refer to the prescribing information for specific dosing guidelines based on the condition being treated.

Mechanism of action

Upto exerts its therapeutic effects by selectively inhibiting Janus kinase 1 (JAK1). This inhibition prevents the phosphorylation and activation of signal transducer and activator of transcription (STAT) proteins, which are crucial for the signaling of numerous pro-inflammatory cytokines. Consequently, the reduced activity of these pathways leads to decreased inflammation and immune response.

Pharmacodynamics

The pharmacodynamics of Upto are characterized by its ability to inhibit the JAK-STAT signaling pathway, leading to a decrease in the production of inflammatory mediators. This results in reduced symptoms of inflammation, such as pain and swelling, and improved clinical outcomes in patients with autoimmune diseases. The onset of action can vary, with some patients reporting improvements within weeks of starting therapy.

Pharmacokinetics

Upto is rapidly absorbed following oral administration, with peak plasma concentrations typically reached within a few hours. It undergoes extensive metabolism primarily via the cytochrome P450 system, particularly CYP3A4. The elimination half-life is approximately 10 hours, allowing for once-daily dosing. Upto is excreted mainly through urine and feces, with a significant portion of the drug being eliminated unchanged.

Contra-indications

• Hypersensitivity to the active substance or any of the excipients
• Severe hepatic impairment
• Severe renal impairment

Adverse effects

• Nausea
• Vomiting
• Diarrhea
• Headache
• Dizziness
• Fatigue
• Allergic reactions including rash and itching

Interactions

• May interact with other central nervous system depressants, increasing sedation
• Potential interactions with drugs metabolized by the liver
• May affect the pharmacodynamics of anticoagulants

Precautions

• Use with caution in patients with hepatic or renal impairment
• Monitor for signs of sedation or respiratory depression
• Consider potential for abuse and dependence

Pregnancy

Limited data is available. Use only if clearly needed and the benefits justify the risks to the fetus.

Breast-feeding

Excreted in breast milk. Use with caution and consider alternative treatments.

Storage

Store in a cool, dry place, away from light. Keep out of reach of children.

Formulations

• Tablets
• Capsules
• Oral solution

Indications

• Used as a thickening agent in food products
• Utilized in pharmaceutical formulations as a stabilizer
• Employed in cosmetics for texture improvement
• Applied in industrial products for its viscosity properties

Dosage

Children: Refer to specific product guidelines for appropriate use. Xanthan is used in formulations as a thickener or stabilizer, and dosage should be evaluated based on the specific product and formulation.

Adults: Refer to specific product guidelines for appropriate use. Xanthan is typically used in small quantities as a thickener or stabilizer in food and pharmaceutical products.

Mechanism of action

Xanthan functions primarily as a thickener and stabilizer. It acts by interacting with water molecules to form a gel-like consistency, which enhances the texture and stability of products. Its unique rheological properties allow it to maintain viscosity under varying conditions, which is beneficial in food and pharmaceutical applications.

Pharmacodynamics

Xanthan's action is primarily physical rather than pharmacological. It does not exert a direct therapeutic effect but influences the delivery and stability of active ingredients in formulations. The gel formation and viscosity changes help ensure the uniform distribution of substances in liquid formulations, which can improve the effectiveness of the drug delivery.

Pharmacokinetics

As xanthan is a polysaccharide, it is not absorbed in the gastrointestinal tract when ingested. It passes through the digestive system largely unchanged. In terms of metabolism, xanthan is broken down by colonic bacteria, resulting in short-chain fatty acids. Its pharmacokinetic profile indicates that it has a low bioavailability due to its large molecular size and structure.

Pregnancy

There is insufficient data on the use of xanthan during pregnancy. Consult a healthcare professional before use.

Breast-feeding

There is insufficient data on the excretion of xanthan in human milk. Consult a healthcare professional before use.

Storage

Store in a cool, dry place, away from direct sunlight.

Formulations

• Xanthan gum powder

Mechanism of action

Vitamin B12 serves as a cofactor for _methionine synthase_ and _L-methylmalonyl-CoA mutase_ enzymes. Methionine synthase is essential for the synthesis of purines and pyrimidines that form DNA. L-methylmalonyl-CoA mutase converts L-methylmalonyl-CoA to _succinyl-CoA_ in the degradation of propionate, an important reaction required for both fat and protein metabolism. It is a lack of vitamin B12 cofactor in the above reaction and the resulting accumulation of methylmalonyl CoA that is believed to be responsible for the neurological manifestations of B12 deficiency. Succinyl-CoA is also necessary for the synthesis of hemoglobin. In tissues, vitamin B12 is required for the synthesis of _methionine_ from homocysteine. Methionine is required for the formation of S-adenosylmethionine, a methyl donor for nearly 100 substrates, comprised of DNA, RNA, hormones, proteins, as well as lipids. Without vitamin B12, tetrahydrofolate cannot be regenerated from 5-methyltetrahydrofolate, and this can lead to functional folate deficiency,. This reaction is dependent on methylcobalamin (vitamin B12) as a co-factor and is also dependent on folate, in which the methyl group of methyltetrahydrofolate is transferred to homocysteine to form _methionine_ and _tetrahydrofolate_. Vitamin B12 incorporates into circulating folic acid into growing red blood cells; retaining the folate in these cells. A deficiency of vitamin B12 and the interruption of this reaction leads to the development of megaloblastic anemia.

Pharmacodynamics

**General effects** Cyanocobalamin corrects vitamin B12 deficiency and improves the symptoms and laboratory abnormalities associated with pernicious anemia (megaloblastic indices, gastrointestinal lesions, and neurologic damage). This drug aids in growth, cell reproduction, hematopoiesis, nucleoprotein, and myelin synthesis. It also plays an important role in fat metabolism, carbohydrate metabolism, as well as protein synthesis. Cells that undergo rapid division (for example, epithelial cells, bone marrow, and myeloid cells) have a high demand for vitamin B12. **Parenteral cyanocobalamin effects** The parenteral administration of vitamin B12 rapidly and completely reverses the megaloblastic anemia and gastrointestinal symptoms of vitamin B12 deficiency. Rapid parenteral administration of vitamin B12 in deficiency related neurological damage prevents the progression of this condition. **Nasal spray effects** In 24 vitamin B12 deficient patients who were already stabilized on intramuscular (IM) vitamin B12 therapy, single daily doses of intranasal cyanocobalamin for 8 weeks lead to serum vitamin B12 concentrations that were within the target therapeutic range (>200 ng/L).

Mechanism of action

...Some quartz and cristobalite dusts (crystalline) as well as the diatomaceous earths (amorphous), but not the pyrogenic amorphous silica, were cytotoxic and induced morphological transformation of SHE cells in a concentration-dependent manner. The ranking in cytotoxicity was different from that in transforming potency, suggesting two separate molecular mechanisms for the two effects. The cytotoxic and transforming potencies were different from one dust to another, even among the same structural silicas. The type of crystalline structure (quartz vs cristobalite) and the crystalline vs biogenic amorphous form did not correlate with cytotoxic or transforming potency of silica dusts. Comparison of cellular effects induced by original and surface modified samples revealed that several surface functionalities modulate cytotoxic and transforming potencies. The cytotoxic effects appeared to be related to the distribution and abundance of silanol groups and to the presence of trace amounts of iron on the silica surface. Silica particles with fractured surfaces and/or iron-active sites, able to generate reactive oxygen species, induced SHE cell transformation. The results show that the activity of silica at the cellular level is sensitive to the composition and structure of surface functionalities and confirm that the biological response to silica is a surface originated phenomenon. In vivo exposure of rat lungs to crystalline silica either by intratracheal instillation or by inhalation results in an increase in mRNA levels for inducible nitric oxide synthase (iNOS) in bronchoalveolar lavage cells (BALC), elevated nitric oxide (.NO) production by BALC, and an increase in .NO-dependent chemiluminescence (CL) from alveolar macrophages (AM). Induction of iNOS message occurs in both AM and polymorphonuclear leukocytes (PMN) harvested from silica-exposed lungs but is not significantly elevated in lavaged lung tissue. This review presents characteristics of simple and complicated coal workers' pneumoconiosis (CWP) as well as pathologic indices of acute and chronic silicosis by summarizing results of in vitro, animal, and human investigations. These results support four basic mechanisms in the etiology of CWP and silicosis: a) direct cytotoxicity of coal dust or silica, resulting in lung cell damage, release of lipases and proteases, and eventual lung scarring; b) activation of oxidant production by pulmonary phagocytes, which overwhelms the antioxidant defenses and leads to lipid peroxidation, protein nitrosation, cell injury, and lung scarring; c) activation of mediator release from alveolar macrophages and epithelial cells, which leads to recruitment of polymorphonuclear leukocytes and macrophages, resulting in the production of proinflammatory cytokines and reactive species and in further lung injury and scarring; d) secretion of growth factors from alveolar macrophages and epithelial cells, stimulating fibroblast proliferation and eventual scarring. Results of in vitro and animal studies provide a basis for proposing these mechanisms for the initiation and progression of pneumoconiosis. Data obtained from exposed workers lend support to these mechanisms. /The authors/ reported previously that freshly fractured silica (FFSi) induces activator protein-1 (AP-1) activation through extracellular signal-regulated protein kinases (ERKs) and p38 kinase pathways. In the present study, the biologic activities of FFSi and aged silica (ASi) were compared by measuring their effects on the AP-1 activation and phosphorylation of ERKs and p38 kinase. The roles of reactive oxygen species (ROS) in this silica-induced AP-1 activation were also investigated. FFSi-induced AP-1 activation was four times higher than that of ASi in JB6 cells. FFSi also caused greater phosphorylation of ERKs and p38 kinase than ASi. FFSi generated more ROS than ASi when incubated with the cells as measured by electron spin resonance (ESR). Studies using ROS-sensitive dyes and

Mechanism of action

Most individuals naturally generate adequate amounts of vitamin D through ordinary dietary intake of vitamin D (in some foods like eggs, fish, and cheese) and natural photochemical conversion of the vitamin D3 precursor 7-dehydrocholesterol in the skin via exposure to sunlight. Conversely, vitamin D deficiency can often occur from a combination of insufficient exposure to sunlight, inadequate dietary intake of vitamin D, genetic defects with endogenous vitamin D receptor, or even severe liver or kidney disease. Such deficiency is known for resulting in conditions like rickets or osteomalacia, all of which reflect inadequate mineralization of bone, enhanced compensatory skeletal demineralization, resultant decreased calcium ion blood concentrations, and increases in the production and secretion of parathyroid hormone. Increases in parathyroid hormone stimulate the mobilization of skeletal calcium and the renal excretion of phosphorus. This enhanced mobilization of skeletal calcium leads towards porotic bone conditions. Ordinarily, while vitamin D3 is made naturally via photochemical processes in the skin, both itself and vitamin D2 can be found in various food and pharmaceutical sources as dietary supplements. The principal biological function of vitamin D is the maintenance of normal levels of serum calcium and phosphorus in the bloodstream by enhancing the efficacy of the small intestine to absorb these minerals from the diet. At the liver, vitamin D3 or D2 is hydroxylated to 25-hydroxyvitamin D and then finally to the primary active metabolite 1,25-dihydroxyvitamin D in the kidney via further hydroxylation. This final metabolite binds to endogenous vitamin d receptors, which results in a variety of regulatory roles - including maintaining calcium balance, the regulation of parathyroid hormone, the promotion of the renal reabsorption of calcium, increased intestinal absorption of calcium and phosphorus, and increased calcium and phosphorus mobilization of calcium and phosphorus from bone to plasma to maintain balanced levels of each in bone and the plasma. In particular, calcitriol interacts with vitamin D receptors in the small intestine to enhance the efficiency of intestinal calcium and phosphorous absorption from about 10-15% to 30-40% and 60% increased to 80%, respectively. Furthermore, calcitriol binds with vitamin D receptors in osteoblasts to stimulate a receptor activator of nuclear factor kB ligand (or RANKL) which subsequently interacts with receptor activator of nuclear factor kB (NFkB) on immature preosteoclasts, causing them to become mature bone-resorbing osteoclasts. Such mature osteoclasts ultimately function in removing calcium and phosphorus from bone to maintain blood calcium and phosphorus levels. Moreover, calcitriol also stimulates calcium reabsorption from the glomerular filtrate in the kidneys. Additionally, it is believed that when calcitriol binds with nuclear vitamin D receptors, that this bound complex itself binds to retinoic acid X receptor (RXR) to generate a heterodimeric complex that consequently binds to specific nucleotide sequences in the DNA called vitamin D response elements. When bound, various transcription factors attach to this complex, resulting in either up or down-regulation of the associated gene's activity. It is thought that there may be as much as 200 to 2000 genes that possess vitamin D response elements or that are influenced indirectly to control a multitude of genes across the genome. It is in this way that cholecalciferol is believed to function in regulating gene transcription associated with cancer risk, autoimmune disorders, and cardiovascular disease linked to vitamin D deficiency. In fact, there has been some research to suggest calcitriol may also be able to prevent malignancies by inducing cellular maturation and inducing apoptosis and inhibiting angiogenesis, exhibit anti-inflammatory effects by inhibiting foam cell formation and promoting angiogenesis in en

Pharmacodynamics

The in vivo synthesis of the predominant two biologically active metabolites of vitamin D occurs in two steps. The first hydroxylation of vitamin D3 cholecalciferol (or D2) occurs in the liver to yield 25-hydroxyvitamin D while the second hydroxylation happens in the kidneys to give 1, 25-dihydroxyvitamin D. These vitamin D metabolites subsequently facilitate the active absorption of calcium and phosphorus in the small intestine, serving to increase serum calcium and phosphate levels sufficiently to allow bone mineralization. Conversely, these vitamin D metabolites also assist in mobilizing calcium and phosphate from bone and likely increase the reabsorption of calcium and perhaps also of phosphate via the renal tubules. There exists a period of 10 to 24 hours between the administration of cholecalciferol and the initiation of its action in the body due to the necessity of synthesis of the active vitamin D metabolites in the liver and kidneys. It is parathyroid hormone that is responsible for the regulation of such metabolism at the level of the kidneys.

Mechanism of action

Phosphorus apparently decreases the absorption of intercellular calcified cartilage matrix by osteoclasts, in the metaphyseal region of growing bones. Administration of phosphorus to growing animals or children produces "phosphorus bands" of increased bone density and thickness that are visible grossly or from radiograms. The "phosphorus bands" are observed in the metaphyseal region of growing bones, and represent areas of decreased absorption of the calcified cartilage matrix. Exposure to white phosphorus has been shown to damage the rough endoplasmic reticulum and cause a disaggregation of polyribosomes. This damage results in impairment of protein synthesis, in particular, a decrease in the synthesis of the apolipoprotein portion of very low density lipoproteins (VLDL), which are required for the transport of triglycerides. A significant decrease in protein synthesis has been detected as early as 3 hours after oral exposure. The smooth endoplasmic reticulum is also involved in the formation of the VLDLs, and damage to the smooth endoplasmic reticulum also impairs the formation of VLDLs. The net result of these ultrastructural changes is an accumulation of triglycerides in the liver. This results in steatosis and fibrosis, which is one of the mechanisms involved in the hepatotoxicity of white phosphorus. The mechanism behind the damage to the endoplasmic reticulum is not known; also, it is not known whether white phosphorus itself or a metabolite of white phosphorus is the damaging agent. In addition to these damages, white phosphorus or a metabolite causes damage to the mitochondria and nuclei in the livers of animals orally exposed to white phosphorus. The damage to the mitochondria may impair the cell's ability to produce ATP, thus resulting in necrosis of the cell. Fatty infiltration and/or cellular damage has also been observed in the kidney, brain, and heart. It is possible that white phosphorus (or a metabolite) also impairs the ability of cells in these organs to produce ATP. The mitochondrial damage may also inhibit fatty acid oxidation (also contributing to the decreased availability of ATP) which could result in an accumulation of fat in the organs.

Mechanism of action

Sorbitol exerts its laxative effect by drawing water into the large intestine, thereby stimulating bowel movements. ... Sorbitol exerts hygroscopic and/or local irritant action, drawing water from tissues into feces and reflexly stimulating evacuation. The polyol pathway consists of two enzymes aldose reductase (AR) and sorbitol dehydrogenase (SDH); the former is the first enzyme in the polyol pathway, that catalyzes the reduction of glucose to sorbitol, the latter is the second one, that converts sorbitol to fructose using by NAD(+) as a cofactor. ... SDH activity, the second step in the polyol pathway, might make a greater contribution to the etiology of diabetic retinopathy than does the first step involving AR. /This paper proposes/ a novel hypothesis that polymorphisms of SDH gene may be correlated with SDH gene expression levels in diabetic retinas, thus being a valuable genetic marker for diabetic retinopathy. It has been reported that sorbitol induces apoptosis in several cancer cell lines. ... In /this/ study, the intracellular signaling pathways of sorbitol-induced apoptosis in human K562 cells were investigated using both morphological analysis and DNA fragmentation technique. In this study, we demonstrated that sorbitol-induced apoptosis in human K562 cells is a concentration- and time-dependent manner. This sorbitol-induced apoptosis in human K562 cells was also accompanied by the up-regulation of Bax, and down-regulation of p-Bcl-2, but no effect on the levels of Bcl-X(L). Moreover, the sorbitol treatment resulted in a significant reduction of mitochondria membrane potential, increase in the release of mitochondrial cytochrome c (cyt c), and activation of caspase 3. Furthermore, treatment with caspase 3 inhibitor (z-DEVD-fmk) was capable of preventing the sorbitol-induced caspase 3 activity and cell death. These results clearly demonstrate that the induction of apoptosis by sorbitol involves multiple cellular/molecular pathways and strongly suggest that pro- and anti-apoptotic Bcl-2 family proteins, mitochondrial membrane potential, mitochondrial cyt c, and caspase 3, they all participate in sorbitol-induced apoptotic process in human K562 cells. Chronic diabetic complications, in particular, nephropathy, peripheral and autonomic neuropathy, "diabetic foot," retinopathy, and cardiovascular disease, remain the major cause of morbidity and mortality in patients with diabetes mellitus. Growing evidence indicates that both increased activity of the sorbitol pathway of glucose metabolism and enhanced oxidative stress are the leading factors in the pathogenesis of diabetic complications. The relation between the two mechanisms remains the area of controversy. One group has reported that increased sorbitol pathway activity has a protective rather than detrimental role in complication-prone tissues because the pathway detoxifies toxic lipid peroxidation products. Others put forward a so-called "unifying hypothesis" suggesting that activation of several major pathways implicated in diabetic complications (eg, sorbitol pathway) occurs due to increased production of superoxide anion radicals in mitochondria and resulting poly(ADP-ribose) polymerase activation. This review (a) presents findings supporting a key role for the sorbitol pathway in oxidative stress and oxidative stress-initiated downstream mechanisms of diabetic complications, and (b) summarizes experimental evidence against a detoxifying role of the sorbitol pathway, as well as the "unifying concept."

Mechanism of action

Although systemically applied nanoparticles are quickly taken up by phagocytic cells, mainly macrophages, the interactions between engineered nanoparticles and macrophages are still not well defined. ...Therefore ... the uptake of diagnostically used carboxydextran-coated superparamagnetic iron oxide nanoparticles of 60 nm (SPIO) and 20 nm (USPIO) by human macrophages /was analyzed/. By pharmacological and in vitro knockdown approaches, the principal uptake mechanism for both particles was identified as clathrin-mediated, scavenger receptor A-dependent endocytosis... /Iron oxide nanoparticles/ ... /It has been/ suggested that ferric oxide serves as a carcinogenic cofactor either by retarding the clearance of inhaled carcinogens or by inducing cytopathological changes which make the cells of the respiratory tract more prone to develop cancer when exposed to carcinogenic substances.