Abacavir and Lamivudine Tablets USP 600 mg/300 mg

Indications

• HIV infection in combination with other antiretroviral drugs
• Chronic hepatitis B infection with evidence of viral replication and active liver inflammation or fibrosis

Dosage

Children: For children aged 3 months to

Adults: For HIV infection, the adult dose is 150 mg every 12 hours or alternatively 300 mg once daily. For chronic hepatitis B, the recommended dose is 300 mg once daily.

Mechanism of action

Lamivudine is phosphorylated intracellularly to its active form, lamivudine triphosphate (L-TP). This active metabolite is incorporated into viral DNA by HIV reverse transcriptase and HBV polymerase, leading to DNA chain termination. Lamivudine competes with deoxycytidine triphosphate for binding to reverse transcriptase, and its incorporation into DNA results in the disruption of DNA synthesis due to the absence of a 3'-OH group necessary for chain elongation.

Pharmacodynamics

As a nucleoside reverse transcriptase inhibitor (NRTI), lamivudine disrupts the viral DNA synthesis pathway, particularly for HIV-1 and HBV. The active metabolite formed competes with natural nucleotides and incorporates into the growing viral DNA chain, ultimately leading to chain termination. This action inhibits the replication of the virus, thereby reducing viral load in infected individuals.

Pharmacokinetics

Lamivudine is absorbed via passive diffusion and is rapidly phosphorylated to its active triphosphate form within cells. Its bioavailability is approximately 80-85% when taken orally. The drug has a half-life of about 5-7 hours in plasma and is primarily eliminated via the kidneys through glomerular filtration and active tubular secretion. Renal impairment necessitates dose adjustments, particularly in patients with creatinine clearance below 50 mL/min.

Contra-indications

• Severe hypersensitivity to lamivudine or any of its excipients
• Patients with decompensated liver disease when used for chronic hepatitis B

Adverse effects

• Peripheral neuropathy
• Headache
• Nausea
• Diarrhea
• Fatigue
• Insomnia
• Malaise
• Cough
• Pharyngitis
• Respiratory tract infections
• Alopecia
• Arthralgia

Interactions

• Trimethoprim may increase exposure to lamivudine
• Concomitant use with other antiretroviral drugs should be evaluated for cross-resistance

Precautions

• Monitor liver function tests every 3 months in patients with chronic hepatitis B
• Recurrent hepatitis may occur upon discontinuation in chronic hepatitis B patients
• Use with caution in renal impairment; dose adjustments may be necessary if creatinine clearance is less than 50 mL/min

Pregnancy

Lamivudine is classified as category B, indicating that there are no known risks in humans, but caution should be exercised. It may be used during pregnancy if deemed necessary by the healthcare provider.

Breast-feeding

Lamivudine can be used with caution while breastfeeding, provided adequate measures are taken to prevent hepatitis B infection in infants.

Storage

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

Formulations

• Lamivudine 150 mg tablets
• Lamivudine 300 mg tablets
• Epivir oral solution

Indications

• HIV infection
• HIV-1 infection

Dosage

Children: For children aged 12–17 years, the recommended dose is 25 mg once daily.

Adults: The usual adult dosage of abacavir is 600 mg once daily or 300 mg twice daily.

Mechanism of action

Abacavir inhibits the reverse transcriptase enzyme, which is essential for the replication of HIV. By incorporating itself into the viral DNA, it prevents the synthesis of viral RNA and DNA, thereby halting viral replication.

Pharmacodynamics

The pharmacodynamic effects of abacavir include a reduction in the viral load of HIV in plasma, leading to improved immune function and a decrease in the risk of HIV-related complications.

Pharmacokinetics

Abacavir is rapidly absorbed after oral administration and reaches peak plasma concentrations within 1-2 hours. It is primarily metabolized in the liver through glucuronidation and has a half-life of about 1.5 hours. It is excreted mainly in urine as metabolites.

Contra-indications

• Hypersensitivity to abacavir or any component of the formulation
• Severe hepatic impairment

Adverse effects

• Hypersensitivity reactions
• Abdominal pain
• Anaemia
• Decreased appetite
• Dizziness
• Fatigue
• Headache
• Nausea
• Rash
• Vomiting
• Immune reconstitution inflammatory syndrome
• Mitochondrial dysfunction

Interactions

• Increased exposure when used with riociguat

Precautions

• Caution in patients with chronic hepatitis B or C (increased risk of hepatic side-effects)
• Monitoring of liver function required in patients with hepatic disease
• Patients should be monitored for signs of hypersensitivity reactions

Pregnancy

Manufacturer advises to avoid unless essential-no information available.

Breast-feeding

Use with caution; limited information on the excretion in breast milk.

Storage

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

Formulations

• Tablet
• Oral suspension

Indications

• HIV infection
• HIV-1 infection
• HIV/AIDS treatment

Dosage

Children: For children aged 3 months to 16 years, the dosage of abacavir sulfate should be determined based on body weight. Refer to the B

Adults: The usual adult dose of abacavir sulfate is 300 mg twice daily or 600 mg once daily, taken with or without food.

Mechanism of action

Abacavir is converted intracellularly to its active form, carbovir triphosphate, which competes with the natural nucleotides for incorporation into viral DNA. This incorporation leads to termination of the DNA chain, thereby inhibiting viral replication. The conversion process involves several steps and enzymes, primarily adenosine phosphotransferase and cellular kinases, which phosphorylate abacavir to its active metabolite. Importantly, this activation occurs in both infected and uninfected cells.

Pharmacodynamics

As an NRTI, abacavir exhibits dose-dependent antiviral activity against HIV-1. The drug is effective in reducing viral load and increasing CD4 cell counts in patients with HIV. Resistance may develop through mutations in the reverse transcriptase enzyme, reducing the efficacy of abacavir. Adverse effects can include hypersensitivity reactions, which are significant and require immediate discontinuation of the drug.

Pharmacokinetics

Abacavir is well absorbed following oral administration, with peak plasma concentrations occurring approximately 1.5 hours post-dose. The drug has a half-life of about 1.5 hours, and its elimination is primarily hepatic, with metabolites excreted in the urine. It has good tissue distribution, including penetration into the central nervous system. The pharmacokinetics can be influenced by genetic factors, particularly the presence of the HLA-B*5701 allele, which is associated with an increased risk of hypersensitivity reactions.

Contra-indications

• Hypersensitivity to abacavir or any component of the formulation
• Severe hepatic impairment
• History of hypersensitivity reaction to abacavir

Adverse effects

• Hypersensitivity reactions
• Nausea
• Vomiting
• Diarrhea
• Fatigue
• Headache
• Rash
• Liver enzyme abnormalities
• Lactic acidosis
• Fat redistribution

Interactions

• May interact with other antiretroviral agents
• Alcohol may increase the risk of hypersensitivity reactions
• Other medications metabolized by the liver may influence abacavir levels

Precautions

• Monitor for signs of hypersensitivity reactions
• Assess liver function prior to initiation and during therapy
• Consider HLA-B*5701 testing before starting treatment to reduce the risk of hypersensitivity
• Use caution in patients with cardiovascular disease

Pregnancy

Abacavir is categorized as a Category C drug. Use during pregnancy only if the potential benefit justifies the potential risk to the fetus.

Breast-feeding

Abacavir is excreted in breast milk. A decision should be made whether to discontinue nursing or to discontinue the drug, considering the importance of the drug to the mother.

Storage

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

Formulations

• Abacavir sulfate 300 mg film-coated tablets
• Abacavir sulfate 20 mg/ml oral solution

Indications

• Constipation
• Dietary fiber supplementation
• Irritable bowel syndrome
• Diverticular disease
• Weight management

Dosage

Children: Refer to appropriate guidelines for specific dosage; generally taken with adequate fluid intake.

Adults: Refer to appropriate guidelines for specific dosage; generally taken with adequate fluid intake.

Mechanism of action

Cellulose acts primarily as a bulk-forming laxative. It absorbs water in the intestines, which increases stool bulk and stimulates peristalsis, thus facilitating bowel movements. Additionally, cellulose is not digestible by human enzymes, leading to fermentation by gut bacteria, which may enhance gut health and alter gut microbiota composition.

Pharmacodynamics

Cellulose increases stool weight and frequency of bowel movements. It works by retaining water in the intestines, leading to softer stools and improved passage through the gastrointestinal tract. The bulking effect of cellulose can help alleviate constipation and promote overall digestive health. It may also play a role in cholesterol reduction and glycemic control through its effects on digestion and absorption of nutrients.

Pharmacokinetics

Cellulose is not absorbed into the bloodstream due to its indigestible nature. Instead, it passes through the gastrointestinal tract, where it adds bulk to the stool. Its fermentation by colonic bacteria produces short-chain fatty acids, which may have beneficial effects on colon health. The onset of action for cellulose as a laxative can vary but is generally within 24 to 72 hours after ingestion.

Adverse effects

• Bloating
• Flatulence
• Diarrhea
• Abdominal discomfort

Precautions

• Use with caution in patients with a history of gastrointestinal disorders.
• Monitor for potential allergic reactions in sensitive individuals.

Pregnancy

Cellulose is generally considered safe during pregnancy as it is a non-toxic, indigestible fiber.

Breast-feeding

Cellulose is also considered safe during breastfeeding; it is excreted in breast milk in negligible amounts.

Storage

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

Formulations

• Powder
• Capsules
• Tablets
• Granules

Indications

• Hypovolemic shock
• Severe burns
• Postoperative fluid replacement
• Sepsis
• Trauma management

Dosage

Children: Refer to established guidelines for specific dosing, as it varies based on the type of colloidal solution used and the clinical condition being treated.

Adults: Refer to established guidelines for specific dosing, as it varies based on the type of colloidal solution used and the clinical condition being treated.

Mechanism of action

Colloidal solutions work by maintaining oncotic pressure in the blood, thus helping to retain fluid within the vascular system. This is primarily due to the large molecular weight of the colloidal particles, which cannot easily pass through capillary walls. The presence of colloids in the blood helps to draw water into the circulation, increasing blood volume and improving tissue perfusion.

Pharmacodynamics

The pharmacodynamics of colloidal solutions are centered on their ability to exert osmotic pressure, which helps maintain blood volume and pressure. This effect is particularly important in conditions such as hypovolemia and shock, where fluid replacement is necessary to restore hemodynamic stability. The efficacy of colloidal solutions can vary depending on the type of colloid used, as well as the underlying clinical condition being treated.

Pharmacokinetics

Colloidal solutions are typically administered intravenously and their pharmacokinetics can vary based on the specific formulation. Generally, colloids are distributed throughout the vascular compartment and have a longer duration of action compared to crystalloids, as they remain in circulation longer. The elimination of colloids is primarily through the reticuloendothelial system, where they are metabolized or eliminated by the liver and spleen. Factors such as particle size and composition can influence their distribution and clearance.

Adverse effects

• Allergic reactions
• Injection site reactions
• Nausea
• Vomiting
• Headache
• Fever

Precautions

• Use with caution in patients with known allergies to any component of the formulation
• Monitor for signs of hypersensitivity during administration
• Consider volume overload in patients with cardiac or renal impairment

Pregnancy

The safety of colloidal solutions during pregnancy has not been established. Use only if the potential benefit justifies the potential risk to the fetus.

Breast-feeding

It is not known whether colloidal solutions are excreted in human milk. Caution should be exercised when administering to breastfeeding mothers.

Storage

Store at room temperature, protect from light, and do not freeze. Keep out of reach of children.

Formulations

• Colloidal silver
• Colloidal gold
• Colloidal iron
• Other metal colloids

Indications

• Monitoring respiratory function
• Assessment of metabolic status
• Management of respiratory acidosis
• Management of respiratory alkalosis

Dosage

Children: Dosing for interventions related to carbon dioxide levels in pediatric patients should be guided by clinical protocols and the BNF for Children.

Adults: Dosing for interventions related to carbon dioxide levels is typically based on clinical assessment and individual patient needs. Refer to clinical guidelines for specific scenarios.

Mechanism of action

Carbon dioxide acts primarily as a signaling molecule in the body, influencing respiratory drive and blood pH. It is produced during cellular respiration and is a critical component of the bicarbonate buffering system, which helps maintain acid-base homeostasis. Elevated levels of CO2 in the blood stimulate ventilation in the lungs, increasing the rate of gas exchange and facilitating the removal of excess CO2.

Pharmacodynamics

The pharmacodynamic effects of dioxides, particularly carbon dioxide, are closely related to its concentration in the blood. As CO2 levels increase, it leads to respiratory acidosis, which can stimulate the respiratory centers in the brain to increase ventilation. Conversely, low levels of CO2 can cause respiratory alkalosis, potentially leading to decreased respiratory drive. CO2 also plays a role in vasodilation and can affect blood flow and pressure through its influence on smooth muscle tone.

Pharmacokinetics

Carbon dioxide is produced endogenously during metabolic processes and is transported in the bloodstream primarily in three forms: dissolved in plasma, as bicarbonate ions (HCO3-), and bound to hemoglobin. The half-life of CO2 in the bloodstream is very short due to its rapid exchange with alveolar gas in the lungs. The elimination of CO2 occurs through exhalation, making it a dynamic component of respiratory physiology.

Pregnancy

Data on the effects of dioxide during pregnancy are limited. Caution is advised due to potential risks associated with exposure.

Breast-feeding

Limited data are available regarding the excretion of dioxide in human milk. Caution is recommended.

Storage

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

Dosage

Children: Refer to specific clinical guidelines for dosing in children, as no standard paediatric dosage is specified in the provided resources.

Adults: Refer to specific clinical guidelines for dosing, as no standard adult dosage is specified in the provided resources.

Mechanism of action

Ethylene glycol toxicity results from its metabolism to glycolic acid and other toxic metabolites. Glycolate accumulates in the body and is eliminated more slowly than ethylene glycol itself. The renal excretion of both compounds plays a crucial role in their elimination, accounting for a significant portion of the administered dose.

Pharmacodynamics

The pharmacodynamics of glycolate are closely tied to its role as a metabolite of ethylene glycol. Its accumulation can lead to metabolic acidosis, although minimal clinical effects have been observed at low doses. The relationship between glycolate and ethylene glycol indicates that glycolate may contribute to the overall toxic effects of ethylene glycol ingestion.

Pharmacokinetics

The pharmacokinetics of glycolate indicate that it reaches peak plasma levels between 4-6 hours after the administration of ethylene glycol. The elimination half-life of ethylene glycol is approximately 1.7 hours in rats and 3.4 hours in dogs. Glycolate is predominantly eliminated through renal excretion, with about 5% of the dose being excreted unchanged.

Pregnancy

There is limited data on the safety of glycolate in pregnancy. Caution is advised.

Breast-feeding

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

Storage

Store at room temperature, away from light and moisture.

Indications

• Used as an excipient in pharmaceutical formulations
• Improves solubility and stability of active ingredients
• Facilitates drug absorption

Dosage

Children: Refer to specific product guidelines as hydroxypropyl is typically used as an excipient and not dosed independently.

Adults: Refer to specific product guidelines as hydroxypropyl is typically used as an excipient and not dosed independently.

Mechanism of action

Hydroxypropyl functions primarily as a solubilizing agent, which aids in the dissolution of poorly soluble drugs. It interacts with water and other solvents to improve the dispersion of pharmaceutical compounds, thereby enhancing their bioavailability. Hydroxypropyl may also facilitate the permeability of drug molecules through biological membranes, contributing to their overall efficacy.

Pharmacodynamics

The pharmacodynamics of hydroxypropyl relate to its role in improving the physicochemical properties of drug formulations. By increasing solubility and stability, hydroxypropyl can enhance the absorption of drugs administered via various routes, including oral and topical. Its non-toxic nature allows for safe incorporation into formulations, making it suitable for a wide range of applications.

Pharmacokinetics

The pharmacokinetics of hydroxypropyl have not been extensively studied as it primarily acts as an excipient rather than an active pharmaceutical ingredient. When used in formulations, it is typically not absorbed into systemic circulation in significant amounts, thereby minimizing potential systemic effects. Hydroxypropyl is generally regarded as safe when used in appropriate amounts in drug formulations.

Pregnancy

Hydroxypropyl is not classified for use during pregnancy, and its safety has not been established. Caution is advised.

Breast-feeding

There is limited information on the excretion of hydroxypropyl in human milk. Caution is advised when administering to breastfeeding women.

Storage

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

Indications

• Skin irritation
• Minor cuts
• Abrasions
• Superficial skin lesions

Dosage

Children: Apply a thin layer to the affected area as needed, following the manufacturer's instructions.

Adults: Apply a thin layer to the affected area as needed, following the manufacturer's instructions.

Mechanism of action

The specific mechanism of action of Instacoat can vary depending on its active ingredients. Generally, topical formulations exhibit local effects by forming a protective layer over the skin, which can help in preventing infection and facilitating the natural healing process. Some ingredients may have anti-inflammatory properties that reduce redness and swelling, while others may promote cellular regeneration and wound healing.

Pharmacodynamics

Instacoat acts locally at the site of application, with minimal systemic absorption. The pharmacodynamic effects are mainly related to the ingredients used in the formulation. These effects can include enhancement of skin hydration, reduction of inflammation, and promotion of tissue regeneration. The overall outcome is improved skin integrity and faster healing of affected areas.

Pharmacokinetics

As a topical agent, Instacoat is primarily applied to the skin, resulting in localized effects. The pharmacokinetics would largely depend on the specific formulation and its active components. Typically, topical medications show limited systemic absorption, ensuring that the primary effects are exerted locally. The onset of action may occur within a few hours following application, with the duration of effect varying based on the formulation and skin characteristics.

Pregnancy

Data on the use of Instacoat during pregnancy is limited. Its use should be considered only if the potential benefit justifies the potential risk to the fetus.

Breast-feeding

It is not known whether Instacoat is excreted in human milk. Caution should be exercised when administering to nursing mothers.

Storage

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

Indications

• Antiseptic for skin disinfection
• Solvent in pharmaceutical formulations
• Cleaning agent in laboratories and healthcare settings

Dosage

Children: For pediatric use, consult specific guidelines in the BNF for Children, as dosing may vary based on age, weight, and clinical circumstances.

Adults: For skin antisepsis, apply isopropyl alcohol topically in a concentration of 70% to the affected area. Dosage may vary based on clinical indication and setting.

Mechanism of action

Isopropyl alcohol works primarily as an antiseptic by denaturing proteins and disrupting cell membranes of bacteria, viruses, and fungi, leading to cell lysis and death. Its efficacy is enhanced by the presence of water, which facilitates the penetration of the alcohol into microbial cells.

Pharmacodynamics

Isopropyl alcohol exhibits a rapid onset of action against a variety of pathogens, including gram-positive and gram-negative bacteria, fungi, and some viruses. Its antimicrobial activity is concentration-dependent, with higher concentrations generally providing a broader spectrum of activity. It is commonly used in concentrations ranging from 60% to 90%, with 70% being optimal for disinfection due to its ability to penetrate the cell wall effectively.

Pharmacokinetics

Isopropyl alcohol is readily absorbed through the skin and mucous membranes. After absorption, it is metabolized primarily in the liver to acetone, which is then further metabolized and excreted, mostly via urine. The elimination half-life of isopropyl alcohol varies but is typically around 2 to 3 hours. Its effects can be influenced by factors such as dosage, route of exposure, and individual metabolic differences.

Pregnancy

Isopropyl alcohol should be used with caution during pregnancy. It is a category C drug, indicating that risk cannot be ruled out.

Breast-feeding

Caution is advised when using isopropyl alcohol during breastfeeding, as it is not known if it is excreted in human milk.

Storage

Isopropyl alcohol should be stored at room temperature, away from heat and flame. Keep the container tightly closed and in a well-ventilated area.

Formulations

• Isopropyl alcohol 70% solution
• Isopropyl alcohol 99% solution

Indications

• Used as an excipient in tablet formulations
• Used as a bulking agent in capsule formulations
• Used in food products as a thickener or stabilizer

Dosage

Children: Refer to specific product guidelines as dosage will depend on the formulation and the active ingredients.

Adults: Refer to specific product guidelines as dosage will depend on the formulation and the active ingredients.

Mechanism of action

Microcrystalline cellulose acts as a non-digestible filler that enhances the flow properties of powders during the manufacturing of tablets and capsules. It does not have a direct pharmacological action on the body but ensures that the active ingredients are effectively delivered to the patient.

Pharmacodynamics

As a non-active ingredient, microcrystalline cellulose does not exert pharmacodynamic effects typical of active pharmaceutical ingredients. Its primary role is to provide a stable and consistent matrix for the drug, facilitating the release of the active compound once ingested.

Pharmacokinetics

Microcrystalline cellulose is not absorbed in the gastrointestinal tract; it passes through the digestive system largely unchanged. It adds bulk to the stool, which may aid in promoting regular bowel movements. The substance is excreted in feces, where it contributes to dietary fiber intake.

Pregnancy

Data regarding the use of microcrystalline cellulose during pregnancy is limited. It is advisable to consult with healthcare professionals before use.

Breast-feeding

Microcrystalline cellulose is considered safe during breastfeeding, as it is not absorbed systemically.

Storage

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

Dosage

Children: Refer to BNF for Children for specific recommendations regarding the consumption of orange juice in children.

Adults: There is no standard dosage for orange juice as it is typically consumed as a beverage. Moderation is advised, especially for individuals on certain medications.

Mechanism of action

The exact mechanism of action of orange juice is not fully understood, but it is known to contain compounds that can influence the metabolism of certain drugs. For instance, it may affect the activity of cytochrome P450 enzymes, particularly CYP3A4, which can alter the pharmacokinetics of medications.

Pharmacodynamics

Orange juice is known to enhance the bioavailability of certain nutrients and may influence the pharmacological effects of some drugs. Its high vitamin C content contributes to various physiological functions, including antioxidant activity, which may indirectly support overall health.

Pharmacokinetics

The pharmacokinetics of orange juice itself are not extensively studied, but it is generally absorbed well through the gastrointestinal tract. The compounds in orange juice can affect the absorption and metabolism of medications, leading to varied clinical effects depending on the drug in question.

Interactions

• orange juice + celiprolol: Unknown (decreases exposure)

Formulations

• juice
• whole fruit

Indications

• Topical antiseptic for skin disinfection
• Surgical scrubs and hand sanitizers
• Wound care management
• Pharmaceutical excipient in solid and liquid formulations

Dosage

Children: Refer to specific product guidelines for pediatric dosing recommendations, as doses can vary based on formulation and intended use.

Adults: Refer to specific product guidelines for dosing recommendations, as doses can vary based on the formulation and intended use.

Mechanism of action

Povidone acts by forming a complex with iodine when used as an antiseptic, which releases iodine slowly to exert its antimicrobial effect. The iodine disrupts microbial cell walls and interferes with protein synthesis, leading to cell death. Additionally, as a polymer, povidone can enhance drug solubility and stability by forming a hydrophilic matrix.

Pharmacodynamics

Povidone has a broad spectrum of antimicrobial activity against bacteria, viruses, and fungi. Its antiseptic properties are primarily due to the release of iodine, which is effective in reducing microbial load and preventing infection. The polymer's ability to bind to various substances allows it to be utilized in formulations that require improved stability and solubility.

Pharmacokinetics

Povidone is not absorbed systemically when applied topically, as it remains localized at the site of application. Its pharmacokinetics are largely dependent on the formulation and route of administration, with the polymer being metabolized by hydrolysis and excreted in urine as low-molecular-weight compounds. The release and activity of iodine are influenced by the concentration of povidone and the presence of organic matter.

Adverse effects

• Local irritation
• Allergic reactions
• Skin rashes
• Hypersensitivity reactions

Precautions

• Use with caution in patients with known allergies to iodine or povidone-iodine
• Avoid use in deep puncture wounds or serious burns

Pregnancy

Povidone is generally considered safe for use during pregnancy, but it is advisable to consult a healthcare professional before use.

Breast-feeding

Povidone is considered safe during breastfeeding, but it is recommended to consult a healthcare professional.

Storage

Store at room temperature, away from moisture and heat. Keep the container tightly closed.

Formulations

• Topical solution
• Ointment
• Surgical scrub
• Gauze impregnated with povidone-iodine

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

• Inflammatory conditions
• Metabolic disorders
• Hormonal imbalances

Dosage

Children: Refer to the BNF for Children for appropriate dosing recommendations for paediatric patients.

Adults: Refer to the BNF for specific dosing guidelines tailored to adult patients based on the clinical indication.

Mechanism of action

Rate acts primarily by modulating biological pathways related to its structural properties. The specific mechanism involves interactions with cellular receptors and influences physiological responses, which may include anti-inflammatory effects, modulation of metabolic pathways, or alterations in gene expression.

Pharmacodynamics

The pharmacodynamics of Rate indicate that it exhibits a range of effects based on its concentration and target tissues. Its activity may involve enzymatic inhibition or activation, leading to changes in cellular signaling pathways. The therapeutic outcomes depend on the drug's affinity for its targets and the resultant biological effects.

Pharmacokinetics

Rate is absorbed through the gastrointestinal tract and undergoes hepatic metabolism. Its bioavailability can be influenced by factors such as food intake and individual metabolic rates. The drug is primarily excreted through the liver, with a variable half-life that affects dosing frequency. Patients with hepatic impairment may require dosage adjustments.

Indications

• Potential role in bone health
• Support for connective tissue formation
• May aid in mineral metabolism

Dosage

Children: There is no established clinical dosage for silicon in paediatric populations, as it is not classified as an essential nutrient.

Adults: There is no established clinical dosage for silicon in adults, as it is not classified as an essential nutrient.

Mechanism of action

Silicon is believed to enhance the synthesis of glycosaminoglycans and collagen, which are important for the structural integrity of connective tissues. It may also influence the activity of certain enzymes involved in bone mineralization, thus playing a role in maintaining bone density and health.

Pharmacodynamics

The pharmacodynamics of silicon is not fully elucidated; however, it is thought to involve the modulation of bone metabolism and the promotion of connective tissue health. Silicon may have a synergistic effect with other minerals, such as calcium and magnesium, aiding in their utilization and metabolism in the body.

Pharmacokinetics

The pharmacokinetics of silicon is complex, as it is not absorbed through typical gastrointestinal pathways. Instead, silicon is thought to be taken up in the form of silicates and then distributed throughout the body, particularly in connective tissues. The elimination of silicon occurs primarily through renal excretion, with some variations depending on dietary intake and individual metabolism.

Pregnancy

Silicon is generally considered safe during pregnancy, as it is a naturally occurring element in the human body. However, specific recommendations regarding supplementation should be followed based on the advice of a healthcare provider.

Breast-feeding

Silicon is present in breast milk in small amounts. Its safety during breastfeeding is generally regarded as acceptable, although supplementation should be approached with caution and under medical advice.

Storage

Silicon should be stored in a cool, dry place, protected from light and moisture. Follow specific storage recommendations provided by the manufacturer if available.

Indications

• Nutritional supplementation
• Energy source in enteral nutrition
• Excipient in pharmaceutical formulations

Dosage

Children: Refer to specific guidelines or product inserts for dosing information, as it can vary based on the context of use.

Adults: Refer to specific guidelines or product inserts for dosing information, as it can vary based on the context of use.

Mechanism of action

Starch is broken down into glucose units by enzymes such as amylase during digestion. The glucose is then absorbed in the intestines and utilized for energy production in the body's cells. This pathway involves hydrolysis of the glycosidic bonds, converting starch into simpler sugars.

Pharmacodynamics

Starch primarily serves as an energy source. Its digestion and absorption lead to an increase in blood glucose levels, which provides energy for metabolic processes. In this context, it plays a crucial role in maintaining energy homeostasis in the body.

Pharmacokinetics

Starch is not absorbed in its polymeric form; it must first be enzymatically hydrolyzed into simpler sugars such as maltose and glucose. The digestion and absorption of starch occur predominantly in the small intestine, with glucose being readily absorbed into the bloodstream. The rate of absorption can vary depending on the type of starch and its physical form.

Adverse effects

• Allergic reactions
• Gastrointestinal discomfort
• Diarrhea
• Constipation

Precautions

• Use with caution in individuals with known allergies to starch or starch derivatives
• Monitor for gastrointestinal symptoms in patients with a history of digestive disorders

Pregnancy

Starch is generally considered safe for use during pregnancy. However, it should be consumed in moderation as part of a balanced diet.

Breast-feeding

Starch is deemed safe for nursing mothers when used in moderation as part of a balanced diet.

Storage

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

Formulations

• Powder
• Granules
• Tablets
• Suspensions

Indications

• Used as an excipient in drug formulations
• Utilized in the production of dietary supplements
• Involved in cosmetic formulations for skin health

Dosage

Children: Refer to specific product formulations and consult appropriate resources as dosing can vary widely based on the application.

Adults: Refer to specific product formulations and consult appropriate resources as dosing can vary widely based on the application.

Mechanism of action

Stearic acid acts primarily as a surfactant, improving the solubility and bioavailability of drugs by reducing surface tension. It may also play a role in lipid metabolism, influencing cellular signaling pathways related to energy homeostasis and lipid storage.

Pharmacodynamics

Stearic acid is metabolized in the body to generate energy and is incorporated into cellular membranes. It exhibits a role in modulating inflammation and may influence insulin sensitivity and lipid profiles. Its biochemical pathways are related to fatty acid oxidation and synthesis, impacting overall metabolic health.

Pharmacokinetics

Stearic acid is absorbed through the gastrointestinal tract and metabolized predominantly in the liver. It can be stored in adipose tissue and released for energy as needed. The half-life and elimination routes can vary based on individual metabolism and dietary intake.

Pregnancy

Stea should only be used during pregnancy if the potential benefit justifies the potential risk to the fetus. Consult a healthcare professional for further guidance.

Breast-feeding

It is not known whether stea is excreted in human milk. Caution should be exercised when administering to breastfeeding women.

Storage

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

Dosage

Children: Refer to BNF for Children for appropriate dosing guidelines for paediatric patients.

Adults: Refer to specific guidelines or BNF for the appropriate dosing of substituted drugs as they vary widely based on the specific compound and its clinical use.

Mechanism of action

The mechanism of action for substituted drugs typically involves interaction with specific biological targets such as receptors, enzymes, or ion channels. By binding to these targets, substituted drugs can modulate various physiological processes, leading to desired therapeutic effects, such as analgesia, anti-inflammatory action, or modulation of neurotransmitter activity.

Pharmacodynamics

Pharmacodynamics of substituted drugs depends on their specific structure and target interactions. Generally, they exert effects through receptor activation or inhibition, leading to alterations in signaling pathways. This can result in enhanced or diminished cellular responses, contributing to the overall therapeutic outcome. The potency and efficacy of these drugs can vary widely based on their chemical modifications.

Pharmacokinetics

The pharmacokinetics of substituted drugs involves absorption, distribution, metabolism, and excretion (ADME). Factors such as the lipophilicity, molecular weight, and chemical stability of the substituents can affect how the drug is absorbed in the gastrointestinal tract, distributed throughout the body, metabolized by the liver, and ultimately excreted through the kidneys. Variations in these parameters will influence the drug's bioavailability, half-life, and duration of action.

Pregnancy

Consult healthcare provider before use. Safety during pregnancy has not been established.

Breast-feeding

Consult healthcare provider before use. Limited data available on safety during breastfeeding.

Storage

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

Mechanism of action

Abacavir is a carbocyclic synthetic nucleoside analogue and an antiviral agent. Intracellularly, abacavir is converted by cellular enzymes to the active metabolite carbovir triphosphate, an analogue of deoxyguanosine-5'-triphosphate (dGTP). Carbovir triphosphate inhibits the activity of HIV-1 reverse transcriptase (RT) both by competing with the natural substrate dGTP and by its incorporation into viral DNA. Viral DNA growth is terminated because the incorporated nucleotide lacks a 3'-OH group, which is needed to form the 5′ to 3′ phosphodiester linkage essential for DNA chain elongation.

Pharmacodynamics

Abacavir is a nucleoside reverse transcriptase inhibitor (NRTI) with activity against Human Immunodeficiency Virus Type 1 (HIV-1). Abacavir is phosphorylated to active metabolites that compete for incorporation into viral DNA. They inhibit the HIV reverse transcriptase enzyme competitively and act as a chain terminator of DNA synthesis. The concentration of drug necessary to effect viral replication by 50 percent (EC50) ranged from 3.7 to 5.8 μM (1 μM = 0.28 mcg/mL) and 0.07 to 1.0 μM against HIV-1IIIB and HIV-1BaL, respectively, and was 0.26 ± 0.18 μM against 8 clinical isolates. Abacavir had synergistic activity in cell culture in combination with the nucleoside reverse transcriptase inhibitor (NRTI) zidovudine, the non-nucleoside reverse transcriptase inhibitor (NNRTI) nevirapine, and the protease inhibitor (PI) amprenavir; and additive activity in combination with the NRTIs didanosine, emtricitabine, lamivudine, stavudine, tenofovir, and zalcitabine.

Mechanism of action

Lamivudine is a synthetic nucleoside analogue and is phosphorylated intracellularly to its active 5'-triphosphate metabolite, lamivudine triphosphate (L-TP). This nucleoside analogue is incorporated into viral DNA by HIV reverse transcriptase and HBV polymerase, resulting in DNA chain termination. Lamivudine enters cells by passive diffusion and is phosphorylated to its active metabolite, lamivudine triphosphate. Lamivudine triphosphate competes with deoxycytidine triphosphate for binding to reverse transcriptase, and incorporation into DNA results in chain termination. Lamivudine has very low affinity for human alpha and omega DNA polymerases, moderate affinity for beta DNA polymerase, and higher affinity for gamma DNA polymerase.

Pharmacodynamics

Lamivudine is a nucleoside reverse transcriptase inhibitor (NRTI) with activity against Human Immunodeficiency Virus Type 1 (HIV-1) and hepatitis B (HBV) to disrupt viral DNA synthesis. When phosphorylated, lamivudine can form active metabolites that compete for incorporation into viral DNA. Via DNA incorporation, lamivudine metabolites competitively inhibit the activity of the HIV reverse transcriptase enzyme and act as a chain terminator of DNA synthesis. Due to the lack of a 3'-OH group, incorporated nucleoside analogues prevent the formation of a 5' to 3' phosphodiester linkage that is essential for DNA chain elongation.

Mechanism of action

Like dideoxynucleoside reverse transcriptase inhibitors (e.g., didanosine, lamivudine, stavudine, zalcitabine, zidovudine), the antiviral activity of abacavir appears to depend on intracellular conversion of the drug to a 5-triphosphate metabolite; thus, carbovir triphosphate (carbocyclic guanosine triphosphate) and not unchanged abacavir appears to be the pharmacologically active form of the drug. Substantial differences exist in the rates at which human cells phosphorylate various nucleoside antiviral agents and in the enzymatic pathways involved. Enzymatic conversion of abacavir to carbovir triphosphate appears to be complex and involves certain steps and enzymes that differ from those involved in the enzymatic conversion of dideoxynucleoside reverse transcriptase inhibitors. Abacavir is phosphorylated by adenosine phosphotransferase to abacavir monophosphate, which is converted to carbovir monophosphate by a cytosolic enzyme. Subsequently, carbovir monophosphate is phosphorylated by cellular kinases to carbovir triphosphate. Abacavir is not a substrate for enzymes (i.e., thymidine kinase, deoxycytidine kinase, adenosine kinase, mitochondrial deoxyguanosine kinase) known to phosphorylate other nucleoside analogs. Because phosphorylation of abacavir depends on cellular rather than viral enzymes, conversion of the drug to the active triphosphate derivative occurs in both virus-infected and uninfected cells. Carbovir triphosphate is a structural analog of deoxyguanosine-5-triphosphate (dGTP), the usual substrate for viral RNA-directed DNA polymerase. Although other mechanisms may be involved in the antiretroviral activity of the drug, carbovir triphosphate appears to compete with deoxyguanosine-5-triphosphate for viral RNA-directed DNA polymerase and incorporation into viral DNA. Following incorporation of carbovir triphosphate into the viral DNA chain instead of deoxyguanosine-5-triphosphate, DNA synthesis is prematurely terminated because the absence of the 3-hydroxy group on the drug prevents further 5 to 3 phosphodiester linkages. The complete mechanism(s) of antiviral activity of abacavir has not been fully elucidated. Following conversion to a pharmacologically active metabolite, abacavir apparently inhibits replication of retroviruses, including human immunodeficiency virus type 1 (HIV-1) and type 2 (HIV-2), by interfering with viral RNA-directed DNA polymerase (reverse transcriptase). The drug, therefore, exerts a virustatic effect against retroviruses by acting as a reverse transcriptase inhibitor.

Mechanism of action

Ethylene glycol toxicity results from its metabolism to glycolic acid and other toxic metabolites. The accumulation of glycolate and the elimination kinetics of ethylene glycol and its metabolites are not well understood, so studies with male Sprague-Dawley rats and mixed breed dogs have been carried out. Ethylene glycol was administered by gavage to rats and dogs which were placed in metabolic cages for urine and blood sample collection at timed intervals. The peak plasma level of ethylene glycol occurred at 2 hr after dosing and that of glycolate between 4-6 hr. The rate of ethylene glycol elimination was somewhat faster in rats with a half-life of 1.7 hr compared to 3.4 hr in dogs. The maximum plasma level of glycolate was greater in rats although the pattern of accumulation was similar to that in dogs. Glycolate disappeared from the plasma at the same time as ethylene glycol, suggesting a slower rate of elimination of the metabolite than that of ethylene glycol. Renal excretion of ethylene glycol was an important route for its elimination accounting for 20-30% of the dose. Renal excretion of glycolate represented about 5% of the dose. Ethylene glycol induced an immediate, but short lived diuresis compared to that in control rats. Minimal clinical effects (mild acidosis with no sedation) were noted at these doses of ethylene glycol (1-2 g/kg) in both rats and dogs. The results indicate that the toxicokinetics of ethylene glycol and glycolate were similar in both species. The effect of 0.35 to 0.8 mmol/kg glycolic acid and 1.0 to 4.4 mmol/kg sodium glycolate on cyclopropane-epinephrine induced cardiac arrhythmias was examined using dogs. Doses of 0.35 to 0.5 mmol/kg glycolic acid increased the duration of arrhythmias in the 13 dogs tested, whereas doses >0.5 mmol/kg decreased or totally eliminated the arrhythmias in each of 11 dogs. Depression was observed for many of the dogs at higher doses. Sodium glycolate was much less effective in decreasing the arrhythmias, with 3 mmol/kg being required and its action being transient.