Furazol

Indications

• Amebiasis
• Trichomoniasis
• Giardiasis
• Anaerobic bacterial infections
• Bacterial vaginosis
• Clostridium difficile infection

Dosage

Children: For children aged 1 month to 11 years, 7.5 mg/kg every 8 hours for 7 days (maximum dose 400 mg). For children aged 12-17 years, 400 mg every 8 hours for 7 days.

Adults: 1 g three times a day for 3 days, then 1 g twice daily for a total treatment duration of 7 days. In cases of Clostridium difficile infection, treatment may extend to 10 days.

Mechanism of action

The exact mechanism of action of metronidazole is not fully established. However, it is believed that anaerobic bacteria and protozoa reduce metronidazole to reactive intermediates that bind to DNA and inhibit nucleic acid synthesis, leading to cell death. Metronidazole is selectively activated in anaerobic conditions, making it effective against obligate anaerobes.

Pharmacodynamics

Metronidazole exhibits both antibacterial and antiprotozoal activities, effectively treating infections caused by anaerobic bacteria. It demonstrates significant antibacterial activity against most obligate anaerobes but is less effective against facultative anaerobes and obligate aerobes. The drug's cytotoxic effects result from DNA strand damage in susceptible microorganisms, which can lead to cell death. Caution is advised due to the potential for peripheral neuropathy and convulsions, especially at higher doses.

Pharmacokinetics

Metronidazole is well absorbed following oral administration and is distributed widely throughout the body, including the central nervous system. It undergoes hepatic metabolism, primarily through oxidation and conjugation, and is excreted mainly in urine. The pharmacokinetic profile may vary in patients with hepatic impairment, and dosage adjustments may be necessary.

Adverse effects

• Peripheral neuropathy
• Convulsions
• Nausea
• Vomiting
• Diarrhea
• Headache
• Dizziness
• Abdominal cramps
• Metallic taste
• Skin rash

Interactions

• Metronidazole + Coumarins: Increases anticoagulant effect
• Metronidazole + Lithium: Increases concentration
• Metronidazole + Busulfan: Increases risk of toxicity (unknown)
• Metronidazole + Capecitabine: Increases risk of capecitabine toxicity (unknown)
• Metronidazole + Fluorouracil: Increases risk of toxicity (unknown)
• Metronidazole + Alkylating agents: Increases risk of toxicity (unknown)

Precautions

• Caution in patients with history of neurological disorders
• Monitor for signs of peripheral neuropathy
• Use with caution in patients with hepatic impairment
• Avoid excessive alcohol consumption during treatment

Pregnancy

No information available; manufacturer advises avoidance unless essential.

Breast-feeding

Amount in milk probably too small to be harmful.

Storage

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

Formulations

• Metronidazole 0.75% gel
• Metronidazole 0.75% cream
• Metronidazole powder and solvent for nebuliser solution
• Metronidazole injection
• Metronidazole oral tablets (various strengths)

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

• Asymptomatic intestinal amebiasis
• Amebic dysentery (as part of combination therapy)

Dosage

Children: Refer to the BNF for Children for specific paediatric dosing guidelines.

Adults: Refer to the BNF for specific adult dosing guidelines.

Mechanism of action

The exact mechanism of action of diloxanide is unknown. It may inhibit protein synthesis, which contributes to its efficacy against the trophozoites of E. histolytica.

Pharmacodynamics

Diloxanide acts as a luminal amebicide, effectively destroying the trophozoites of Entamoeba histolytica. The drug's action helps in reducing the load of the organism in the intestinal lumen, thereby preventing the formation of cysts and subsequent transmission of the infection.

Pharmacokinetics

Diloxanide is administered orally and is hydrolyzed in the gastrointestinal tract to release the active ingredient. The pharmacokinetics, including absorption, distribution, metabolism, and excretion specifics, are not well-documented, indicating a need for further research in these areas.

Pregnancy

There is limited data on the use of diloxanide during pregnancy. It should only be used if clearly needed.

Breast-feeding

Diloxanide is excreted in breast 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.

Formulations

• tablets

Indications

• Asymptomatic intestinal amebiasis
• Amoebic dysentery (mild cases)

Dosage

Children: Refer to the relevant prescribing information or guidelines.

Adults: Refer to the relevant prescribing information or guidelines.

Mechanism of action

Diloxanide furoate works by inhibiting the growth of the Entamoeba histolytica trophozoites in the intestines. The active metabolite, diloxanide, disrupts the cellular function of the protozoa, leading to cell lysis and death. It is thought to interfere with the protozoan's ability to utilize glucose and other nutrients, thereby inhibiting their metabolic processes.

Pharmacodynamics

Diloxanide furoate's effectiveness against Entamoeba histolytica is due to its ability to alter the protozoan's metabolic pathways, particularly affecting glucose metabolism. This results in a reduction of the organism's viability and ability to replicate. The drug's action is primarily localized to the intestinal lumen, minimizing systemic exposure and associated side effects.

Pharmacokinetics

After oral administration, diloxanide furoate is rapidly absorbed and metabolized to its active form, diloxanide. The drug is extensively metabolized in the liver, with a half-life of approximately 12 hours. It is excreted mainly in the feces, with minimal renal excretion. The bioavailability of diloxanide is enhanced when taken with food, leading to improved therapeutic outcomes.

Adverse effects

• Nausea
• Vomiting
• Diarrhea
• Abdominal pain
• Dizziness
• Headache

Precautions

• Use with caution in patients with a history of gastrointestinal disorders.
• Monitor liver function tests in patients with pre-existing liver conditions.

Pregnancy

There is limited data on the use of diloxanide furoate in pregnancy. It should be used only if clearly needed and the potential benefits justify the potential risks to the fetus.

Breast-feeding

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

Storage

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

Formulations

• Oral tablet
• Oral suspension

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 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.

Indications

• Used in medical devices and containers for fluids
• Used in drug delivery systems

Dosage

Children: Polyvinyl is not a drug and therefore does not have a dosage.

Adults: Polyvinyl is not a drug and therefore does not have a dosage.

Mechanism of action

Polyvinyl does not have a pharmacological mechanism of action as it is a structural material rather than a drug. Its function is primarily physical, providing a safe and effective medium for storage and transport of medical fluids and medications.

Pharmacodynamics

As a polymer, polyvinyl does not exert pharmacodynamic effects typical of active pharmaceutical ingredients. Its role in medicine is to serve as an inert substance that provides a barrier to contamination and ensures the integrity of the contents it holds.

Pharmacokinetics

Polyvinyl is not absorbed or metabolized in the body in the way that drugs are. It remains in a stable form and is excreted unchanged if it enters the body, with no systemic effects or pharmacokinetic profile.

Pregnancy

Polyvinyl products are generally considered safe for use during pregnancy; however, specific formulations should be assessed for safety.

Breast-feeding

Polyvinyl compounds are unlikely to pose a risk during breastfeeding, but exposure should be minimized when possible.

Storage

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

Indications

• Topical drug formulations
• Skin penetration enhancer

Dosage

Children: Refer to the BNF for Children for appropriate formulations and concentrations.

Adults: Refer to specific product guidelines or consult the BNF for appropriate formulations and concentrations.

Mechanism of action

2-Pyrrolidone enhances skin permeation by increasing the diffusivity of polar compounds while decreasing the diffusivity and partitioning of nonpolar compounds through the skin. It acts as a mild accelerant for polar material diffusion, such as methanol, through the human stratum corneum, while inhibiting the transport of nonpolar lipophilic substances.

Pharmacodynamics

Pyrrolidone exhibits unique properties that facilitate the transport of drugs through the skin. Its ability to alter the permeability of the skin barrier allows for enhanced transdermal absorption of active pharmaceutical ingredients, which can lead to improved therapeutic outcomes in topical drug delivery.

Pharmacokinetics

The pharmacokinetics of pyrrolidone involve factors such as its absorption through the skin, distribution within biological tissues, metabolism, and excretion. While specific pharmacokinetic data on 2-pyrrolidone is limited, its role as a skin penetration enhancer suggests that it may exhibit relatively rapid absorption when applied topically. Further studies are needed to elucidate its complete pharmacokinetic profile.

Pregnancy

Safety during pregnancy has not been established. Use only if clearly needed and the benefits outweigh the risks.

Breast-feeding

Not enough data available to determine safety during breastfeeding. Caution is advised.

Storage

Store in a cool, dry place away from light. Keep container tightly closed.

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

Mechanism of action

The exact mechanism of action of metronidazole has not been fully established, however, it is possible that an intermediate in the reduction of metronidazole which is only made by anaerobic bacteria and protozoa, binds deoxyribonucleic acid and electron-transport proteins of organisms, blocking nucleic acid synthesis. After administration, metronidazole enters cells by passive diffusion. Following this, ferredoxin or flavodoxin reduce its nitro group to nitro radicals. The redox potential of the electron transport portions of anaerobic or microaerophilic microorganisms renders metronidazole selective to these organisms, which cause nitro group reduction, leading to the production of toxic metabolites. These include N-(2-hydroxyethyl) oxamic acid and acetamide, which may damage DNA of replicating organisms. Microbicidal; active against most obligate anaerobic bacteria and protozoa by undergoing intracellular chemical reduction via mechanisms unique to anaerobic metabolism. Reduced metronidazole, which is cytotoxic but short-lived, interacts with DNA to cause loss of helical structure, strand breakage, and resultant inhibition of nucleic acid synthesis and cell death. Metronidazole is bactericidal, amebicidal, and trichomonacidal in action. The exact mechanism of action of the drug has not been fully elucidated. Metronidazole is un-ionized at physiologic pH and is readily taken up by anaerobic organisms or cells. In susceptible organisms or cells, metronidazole is reduced by low-redox-potential electron transport proteins (e.g., nitroreductases such as ferredoxin) to unidentified polar product(s) which lack the nitro group. The reduction product(s) appears to be responsible for the cytotoxic and antimicrobial effects of the drug which include disruption of DNA and inhibition of nucleic acid synthesis. Metronidazole is equally effective against dividing and nondividing cells. In in vivo studies in rats given metronidazole in dosages of 2-4 mg/100 g of body weight, the drug reportedly inhibited the development of formalin-induced edema in the rat paw. In vitro in neutrophils, metronidazole has a dose-dependent inhibitory effect on generation of hydrogen peroxide and hydroxyl radicals, oxidants that may cause tissue injury at the site of inflammation. This antioxidant effect appears to be caused by a direct effect on neutrophil function and may contribute to the drug's anti-inflammatory effect in vivo. Results of in vitro studies using leukocytes obtained from patients with Crohn's disease indicate that exposing the cells to metronidazole concentrations of 10 or 50 mcg/mL improved both spontaneous and induced leukocyte migration in cells that previously exhibited reduced migration; the drug had no effect on leukocytes obtained from healthy adults or patients with Crohn's disease when the cells exhibited normal migration prior to exposure to the drug. This effect on leukocyte migration also was observed in vivo in adults with Crohn's disease who received a single 400-mg dose of metronidazole. It has been suggested that metronidazole may increase leukocyte migration by a direct effect on the leukocytes, possibly by causing the release of surface-bound immune complexes from the cell surface.

Pharmacodynamics

Metronidazole treats amebiasis, trichomoniasis, and giardiasis, exerting both antibacterial and antiprotozoal activities. Metronidazole is an effective treatment for some anaerobic bacterial infections. Metronidazole has shown antibacterial activity against the majority of obligate anaerobes, however, during in vitro studies, it does not demonstrate significant action against facultative anaerobes or obligate aerobes. The nitro group reduction of metronidazole by anaerobic organisms is likely responsible for the drug's antimicrobial cytotoxic effects, causing DNA strand damage to microbes. A note on convulsions and neuropathy and carcinogenesis It is important to be aware of the risk of peripheral neuropathy and convulsions associated with metronidazole, especially at higher doses. If convulsions or numbness of an extremity occur, discontinue the drug immediately. Metronidazole has been found to be carcinogenic in mice and rats. The relevance to this effect in humans is unknown. It is advisable to only administer metronidazole when clinically necessary and only for its approved indications.

Mechanism of action

Unknown. Diloxanide may inhibit protein synthesis.

Pharmacodynamics

Diloxanide is a luminal amebicide, however the mechanism of action of diloxanide is unknown. Diloxanide destroys the trophozoites of E. histolytica that eventually form into cysts. The cysts are then excreted by persons infected with asymptomatic amebiasis. Diloxanide furoate is a prodrug, and is hydrolyzed in the gastrointestinal tract to produce diloxanide, the active ingredient.

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.

Mechanism of action

THE MECHANISMS OF SKIN PENETRATION ENHANCERS WERE INVESTIGATED BY MEASURING STEADY-STATE FLUXES IN VITRO FOR MODEL COMPOUNDS, METHANOL, OCTANOL & CAFFEINE. 2-PYRROLIDONE ENHANCED THEIR PERMEATION THROUGH THE POLAR ROUTE OF THE SKIN BY INCREASING THE DIFFUSIVITY & DECREASED PASSAGE THROUGH THE NONPOLAR ROUTE BY DECREASING DIFFUSIVITY & PARTITIONING. TRYPSINIZED, ABDOMINAL STRATUM CORNEUM ABSORBED 1-4 TIMES ITS WT OF PRIMARY ALCOHOLIC VEHICLE FROM SOLUTIONS OF 0-80% WT 2-PYRROLIDONE IN WATER; ABOUT 2 SEPARATION PARTITION COEFFICIENTS OPERATED. CALCULATIONS OF HM VALUES FOR THE PARTITIONS INDICATED THAT 2-PYRROLIDONE IS PROBABLY NOT A PENETRATION ACCELERANT FOR C1-C8 PRIMARY ALCOHOLS. FOR THE SIMPLE NONELECTROLYTES TESTED, & UNDER IDEALIZED IN VITRO STEADY STATE CONDITIONS, 2-PYRROLIDONE ACTED AS A MILD ACCELERANT FOR POLAR MATERIAL (METHANOL) DIFFUSION THROUGH HUMAN STRATUM CORNEUM, BUT INHIBITED NONPOLAR, LIPOPHILIC (OCTANOL) TRANSPORT.