RINAFOL

Indications

• Constipation
• Bowel cleansing

Dosage

Children: Child 1–11 months: 1 g as required, Child 1–11 years: 2 g as required, Child 12–17 years: 4 g as required.

Adults: 4 g as required, usually administered rectally.

Mechanism of action

When administered rectally, glycerol exerts a hygroscopic and/or local irritant action, drawing water from the tissues into the feces and reflexively stimulating evacuation. It decreases intraocular pressure by creating an osmotic gradient between the blood and intraocular fluid, causing fluid to move from the aqueous and vitreous humors into the bloodstream. Glycerol is classified as a hyperosmotic laxative and may also have lubricating and fecal softening effects.

Pharmacodynamics

Glycerol is commonly classified as an osmotic laxative, acting through its local irritant effects and possibly having lubricating and fecal softening actions. Glycerol suppositories usually produce effects within 15 to 30 minutes, providing quick relief from constipation.

Pharmacokinetics

Glycerol is rapidly absorbed through the gastrointestinal tract. It is metabolized in the liver and other tissues, with a half-life that varies depending on the route of administration. Following rectal administration, glycerol is primarily excreted in urine. The pharmacokinetics may vary based on dosage forms and individual patient factors.

Contra-indications

• Acute abdominal conditions
• Acute inflammatory bowel disease
• Intestinal obstruction
• Severe dehydration

Adverse effects

• Abdominal cramps
• Asthenia
• Gastrointestinal disorders
• Hypermagnesaemia
• Skin reactions
• Urine discolouration

Precautions

• Avoid prolonged contact with skin, especially in incontinent patients or infants wearing nappies due to the risk of irritation and excoriation.
• Excessive use may cause diarrhea and related effects such as hypokalaemia.

Pregnancy

Manufacturers advise avoidance due to limited information available.

Breast-feeding

Manufacturers advise avoidance as there is no information available.

Storage

Store at room temperature, away from direct sunlight.

Formulations

• Glycerol 1g suppositories
• Glycerol 2g suppositories
• Glycerol 4g suppositories
• Glycerol oral suspension

Indications

• Fatigue
• Stress management
• Cognitive enhancement
• Immune system support
• General health and wellness

Dosage

Children: Refer to a healthcare professional or specific product guidelines regarding the use of American ginseng in children, as safety and efficacy have not been well established.

Adults: Refer to specific product guidelines, as doses may vary widely based on formulation and intended use.

Mechanism of action

The exact mechanism of action of American ginseng is not fully understood, but it is thought to involve modulation of the immune system and effects on the central nervous system. Compounds called ginsenosides are believed to be responsible for many of its pharmacological effects, which may include enhancing the activity of neurotransmitters, reducing oxidative stress, and influencing hormonal balance.

Pharmacodynamics

American ginseng exhibits various pharmacodynamic effects, including anti-fatigue, anti-stress, and cognitive enhancement properties. It may improve physical performance and increase resistance to stress and fatigue. Its immunomodulatory effects are also notable, as it may enhance the function of immune cells, thereby improving the body’s response to infections.

Pharmacokinetics

American ginseng is typically consumed orally, and its active components, primarily ginsenosides, undergo metabolism in the liver. The bioavailability and pharmacokinetics can vary significantly depending on the formulation and preparation of the ginseng product. Peak plasma concentrations of ginsenosides are usually reached within hours after administration. The elimination half-life of ginsenosides may vary, and factors such as age, sex, and health status can influence how the body processes American ginseng.

Indications

• Allergic rhinitis (hay fever)
• Urticaria (hives)
• Allergic conjunctivitis
• Common cold symptoms

Dosage

Children: For children aged 6-12 years, the dose is typically 2 mg every 4 to 6 hours, not exceeding 12 mg per day. For children under

Adults: The usual adult dose for chlorpheniramine is 4 mg every 4 to 6 hours, not to exceed 24 mg per day.

Mechanism of action

Chlorpheniramine binds to the histamine H1 receptor, preventing endogenous histamine from exerting its effects. This leads to temporary relief from symptoms such as sneezing, pruritus, and increased vascular permeability associated with allergic reactions. The drug competes with histamine for H1-receptor sites on effector cells, thus antagonizing most of the pharmacological effects of histamine, including its actions on smooth muscle and vascular permeability.

Pharmacodynamics

In allergic reactions, allergens trigger the degranulation of mast cells and basophils, leading to the release of histamine. Chlorpheniramine, as an H1 antagonist, competes for receptor binding, effectively blocking histamine-induced effects, such as itching, vasodilation, and bronchoconstriction. This results in relief from symptoms like sneezing, watery eyes, and nasal discharge.

Pharmacokinetics

Chlorpheniramine is well absorbed from the gastrointestinal tract. It undergoes hepatic metabolism and its effects can last for several hours. The onset of action is typically observed within 1 to 2 hours following oral administration, with peak effects occurring around 2 to 6 hours. The drug is eliminated primarily through urine, with a half-life ranging from 12 to 15 hours, though this can vary based on individual factors.

Contra-indications

• Hypersensitivity to chlorpheniramine or any component of the formulation
• Acute asthma attacks
• Severe hypertension
• Narrow-angle glaucoma
• Prostatic hypertrophy

Adverse effects

• Drowsiness
• Dizziness
• Dry mouth
• Blurred vision
• Constipation
• Urinary retention
• Confusion
• Headache

Interactions

• Alcohol
• CNS depressants
• MAO inhibitors
• Anticholinergic agents
• Beta-blockers

Precautions

• Use with caution in patients with cardiovascular disease
• Caution in patients with liver or kidney impairment
• Avoid in elderly patients due to increased risk of sedation and anticholinergic effects
• May impair the ability to drive or operate machinery

Pregnancy

Chlorpheniramine should be used in pregnancy only if clearly needed. Consult medical professionals for guidance.

Breast-feeding

Chlorpheniramine is excreted in breast milk. Caution is advised when administering to nursing mothers.

Storage

Store at room temperature, away from moisture and heat. Keep out of reach of children.

Formulations

• Tablets
• Syrup
• Oral suspension

Indications

• Acidulant in food and beverages
• Preservative in pharmaceutical formulations
• pH adjuster in various chemical preparations

Dosage

Children: Refer to product-specific guidelines for appropriate dosing based on formulation and indication.

Adults: Refer to product-specific guidelines for appropriate dosing based on formulation and indication.

Mechanism of action

Citric acid acts by chelating metal ions, which can enhance the solubility of certain compounds and improve their bioavailability. It also contributes to the acidity of the environment, which can influence enzymatic activity and metabolic pathways, particularly in the degradation of citronellol.

Pharmacodynamics

Citric acid exhibits mild pharmacological effects primarily attributed to its role in metabolic processes. It aids in the regulation of pH levels, which can impact enzymatic reactions and biochemical pathways. The acid's chelating properties may help to reduce the toxicity of certain metal ions in biological systems.

Pharmacokinetics

Citric acid is rapidly absorbed after oral administration and is metabolized in the liver. It undergoes conversion to various metabolites in the citric acid cycle, contributing to energy production. The elimination primarily occurs through urine, with minimal accumulation in the body.

Pregnancy

Citric acid is generally regarded as safe during pregnancy when used in food amounts. However, consult a healthcare provider for advice on medicinal use.

Breast-feeding

Citric acid is considered safe during breastfeeding when consumed in food amounts. For medicinal use, consult a healthcare provider.

Storage

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

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

• 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

• Heartburn
• Acid indigestion
• Upset stomach
• Metabolic acidosis
• Urinary alkalinization

Dosage

Children: Refer to the BNF for Children for specific dosing recommendations for pediatric patients.

Adults: Refer to the BNF for specific dosing guidelines, as doses may vary based on indication and individual patient factors.

Mechanism of action

Carbon dioxide from the tissues diffuses rapidly into red blood cells, where it is hydrated with water to form carbonic acid. This reaction is accelerated by carbonic anhydrase, an enzyme present in high concentrations in red blood cells. The carbonic acid formed dissociates into bicarbonate and hydrogen ions. Most of the bicarbonate ions diffuse into the plasma, allowing for the regulation of blood pH. The Henderson-Hasselbach equation expresses pH in terms of bicarbonate ion concentration and partial pressure of CO2.

Pharmacodynamics

Sodium bicarbonate acts as an alkalizing buffering agent. It dissociates to provide bicarbonate ions, which can neutralize hydrogen ions, leading to systemic alkalinization. This excess bicarbonate can also alkalinize urine when excreted. Additionally, when taken orally, sodium bicarbonate neutralizes stomach acid, providing relief from conditions associated with acidity.

Pharmacokinetics

Sodium bicarbonate is rapidly absorbed from the gastrointestinal tract. It increases plasma bicarbonate levels, thereby affecting the acid-base balance in the body. The onset of action for oral administration is typically within 30 minutes, and its effects can last for several hours depending on the dose and individual metabolism. The elimination half-life is variable, influenced by the body's buffering systems and renal excretion.

Adverse effects

• Gastrointestinal disturbances
• Metabolic alkalosis
• Electrolyte imbalances

Interactions

• May interact with certain medications that require an acidic environment for absorption
• Can influence the pharmacokinetics of drugs like lithium

Precautions

• Use with caution in patients with renal impairment
• Monitor patients with heart failure or hypertension due to sodium content

Pregnancy

Sodium bicarbonate should only be used during pregnancy if the potential benefit justifies the potential risk to the fetus.

Breast-feeding

Sodium bicarbonate is generally considered safe during breastfeeding when used in recommended doses.

Storage

Store in a cool, dry place, away from moisture and heat. Keep tightly closed.

Formulations

• Powder for oral solution
• Tablets

Indications

• Sweetening agent in food and beverages
• Ingredient in pharmaceutical formulations
• Source of quick energy

Dosage

Children: Refer to specific formulations and clinical guidelines for dosing, as sucrose does not have a standardized dosage. Typically used as needed for sweetening.

Adults: Refer to specific formulations and clinical guidelines for dosing, as sucrose does not have a standardized dosage. Typically used as needed for sweetening.

Mechanism of action

Sucrose is metabolized in the body to glucose and fructose, which are then used as energy sources. It does not have a specific pharmacological mechanism of action but contributes to energy metabolism via the glycolytic and citric acid pathways.

Pharmacodynamics

Upon ingestion, sucrose is hydrolyzed by the enzyme sucrase into its constituent monosaccharides, glucose and fructose. These monosaccharides are absorbed in the small intestine and enter the bloodstream, leading to a rise in blood glucose levels. This process provides a quick source of energy for cellular functions.

Pharmacokinetics

Sucrose is rapidly absorbed in the gastrointestinal tract after hydrolysis. Its absorption depends on the presence of sucrase in the intestine. Once in the bloodstream, glucose can be utilized by cells or stored as glycogen in the liver and muscles. The elimination half-life of sucrose itself is not well-defined as it is quickly broken down and utilized.

Pregnancy

Sucrose is generally regarded as safe during pregnancy when consumed in moderation as part of a balanced diet.

Breast-feeding

Sucrose is considered safe during breastfeeding when consumed in normal dietary amounts.

Storage

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

Formulations

• Oral solution
• Granules
• Tablets

Dosage

Children: Refer to product-specific guidelines or consult a healthcare professional.

Adults: Refer to product-specific guidelines or consult a healthcare professional.

Pregnancy

There is limited data on the safety of Sunset during pregnancy, thus it should be used only if clearly needed and prescribed by a healthcare provider.

Breast-feeding

Due to the lack of sufficient studies, it is advised to consult a healthcare professional before using Sunset while breastfeeding.

Storage

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

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

Pregnancy

No specific data available, consult a healthcare professional.

Breast-feeding

No specific data available, consult a healthcare professional.

Storage

Store in a cool, dry place away from light.

Mechanism of action

When administered rectally, glycerin exerts a hygroscopic and/or local irritant action, drawing water from the tissues into the feces and reflexively stimulating evacuation. Glycerin decreases intraocular pressure by creating an osmotic gradient between the blood and intraocular fluid, causing fluid to move out of the aqueous and vitreous humors into the bloodstream. Glycerin (glycerol) and sorbitol are hyperosmotic laxatives. When administered rectally, glycerin and sorbitol exert a hygroscopic and/or local irritant action, drawing water from the tissues into the feces and reflexly stimulating evacuation. The extent to which the simple physical distention of the rectum and the hygroscopic and/or local irritant actions are responsible for the laxative effects of some of these drugs is not known. Only extremely high oral doses of sorbitol (25 g daily) or glycerin exert laxative action. /Glycerin/ decreases intraocular pressure by creating an osmotic gradient between the blood and intraocular fluid, causing fluid to move out of the aqueous and vitreous humors into the bloodstream. The physicochemical effects of a series of alkanols, alkanediols and glycerol on erythrocyte shape and hemolysis at 4 and 20 degrees C were examined. We calculated the dielectric constant of the incubation medium, Ds, and the dielectric constant of the erythrocyte membrane Dm in the presence of organic solutes. The ratio Ds/Dm = -38.48 at 20 degrees C defines the normal biconcave shape in a medium without hemolytic agents. A decrease in Ds/Dm favors externalization or internalization with consequent hemolysis. Alkanols and alkanediols convert biconcave erythrocytes into echinocytes, which is accompanied by an increase in the projected surface area. Glycerol converts biconcave erythrocytes into stomatocytes, which was accompanied by a marginal decrease in the projected surface area. Progressive externalization in alkanols and alkanediols or internalization in glycerol resulted in a decrease in the projected surface area and the formation of smooth spheres. The degree of shape change induced was related to the degree of hemolysis and the ratio Ds/Dm. A decrease in temperature reduced both the degree of shape change and hemolysis. .../Thus/ physicochemical toxicity may be a result of a temperature dependent hydrophobic interaction between the organic solutes and the membrane and is best interpreted by the ability of the solutes to change Ds and Dm.

Pharmacodynamics

Glycerin is commonly classified as an osmotic laxative but may act additionally or alternatively through its local irritant effects; it may also have lubricating and fecal softening actions. Glycerin suppositories usually work within 15 to 30 minutes.

Mechanism of action

Chlorpheniramine binds to the histamine H1 receptor. This blocks the action of endogenous histamine, which subsequently leads to temporary relief of the negative symptoms brought on by histamine. Antihistamines used in the treatment of allergy act by competing with histamine for H1-receptor sites on effector cells. They thereby prevent, but do not reverse, responses mediated by histamine alone. Antihistamines antagonize, in varying degrees, most of the pharmacological effects of histamine, including urticaria and pruritus. Also, the anticholinergic actions of most antihistamines provide a drying effect on the nasal mucosa. /Antihistamines/ H1 antagonists inhibit most responses of smooth muscle to histamine. Antagonism of the constrictor action of histamine on respiratory smooth muscle is easily shown in vivo and in vitro. /Histamine Antagonists: H1 Antagonists/ H1 antagonists strongly block the action of histamine that results in increased permeability and formation of edema and wheal. /Histamine Antagonists: H1 Antagonists/ Within the vascular tree, the H1 antagonists inhibit both the vasoconstrictor effects of histamine and, to a degree, the more rapid vasodilator effects that are mediated by H1 receptors on endothelial cells. Residual vasodilatation reflects the involvement of H2 receptors on smooth muscle and can be suppressed only by the concurrent administration of an H2 antagonist. Effects of the histamine antagonists on histamine induced changes in systemic blood pressure parallel these vascular effects. /Histamine Antagonists: H1 Antagonists/ Many of the H1 antagonists tend to inhibit responses to acetylcholine that are mediated by muscarinic receptors. These atropine like actions are sufficiently prominent in some of the drugs to be manifest during clinical usage ... . /Histamine Antagonists: H1 Antagonists/

Pharmacodynamics

In allergic reactions an allergen interacts with and cross-links surface IgE antibodies on mast cells and basophils. Once the mast cell-antibody-antigen complex is formed, a complex series of events occurs that eventually leads to cell-degranulation and the release of histamine (and other chemical mediators) from the mast cell or basophil. Once released, histamine can react with local or widespread tissues through histamine receptors. Histamine, acting on H₁-receptors, produces pruritis, vasodilatation, hypotension, flushing, headache, tachycardia, and bronchoconstriction. Histamine also increases vascular permeability and potentiates pain. Chlorpheniramine, is a histamine H1 antagonist (or more correctly, an inverse histamine agonist) of the alkylamine class. It competes with histamine for the normal H₁-receptor sites on effector cells of the gastrointestinal tract, blood vessels and respiratory tract. It provides effective, temporary relief of sneezing, watery and itchy eyes, and runny nose due to hay fever and other upper respiratory allergies.

Mechanism of action

Carbon dioxide from the tissues diffuses rapidly into red blood cells, where it is hydrated with water to form carbonic acid. This reaction is accelerated by carbonic anhydrase, an enzyme present in high concentrations in red blood cells. The carbonic acid formed dissociates into bicarbonate and hydrogen ions. Most of the bicarbonate ions diffuse into the plasma. Since the ratio of H2CO3 to dissolved CO2 is constant at equilibrium, pH may be expressed in terms of bicarbonate ion concentration and partial pressure of CO2 by means of the Henderson-Hasselbach equation: pH = pk + log [HCO3-]/aPCO2

Pharmacodynamics

Alkalizing buffering action: Sodium bicarbonate is an alkalinizing agent that dissociates to provide bicarbonate ion. Bicarbonate in excess of that needed to buffer hydrogen ions causes systemic alkalinization and, when excreted, urine alkalinization as well. Oral antacid action: Taken orally, sodium bicarbonate neutralizes stomach acid by the above mechanism.

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.