Imicarbzole

Dosage

Children: Refer to the BNF for Children for appropriate dosing information in paediatric cases, especially in instances of overdose.

Adults: Refer to the BNF for specific dosing information based on clinical circumstances, particularly in cases of overdose.

Mechanism of action

Ethylene glycol is metabolized by alcohol dehydrogenase to glycoaldehyde, which is subsequently converted to glycolic, glyoxylic, and oxalic acids. These metabolites contribute to anion gap metabolic acidosis and are responsible for tissue injury through the formation of insoluble calcium oxalate crystals.

Pharmacodynamics

The toxicity of ethylene glycol arises from its metabolites, particularly glycolic and oxalic acids. These compounds induce metabolic acidosis, lead to renal failure through calcium oxalate crystal deposition in the kidneys, and can cause neurological impairment. The anion gap increases due to the accumulation of these acids, leading to complications such as cardiovascular instability and potential multi-organ failure.

Pharmacokinetics

Ethylene glycol is rapidly absorbed after oral ingestion. It undergoes first-pass metabolism primarily in the liver, where it is converted into its toxic metabolites. The elimination half-life of ethylene glycol varies but is generally prolonged in cases of renal impairment. Renal excretion of metabolites contributes to the duration of toxicity, necessitating prompt medical intervention in cases of overdose.

Adverse effects

• Metabolic acidosis
• Renal failure
• CNS depression
• Hypocalcemia
• Cardiovascular collapse
• Pulmonary edema

Precautions

• Use with caution in patients with renal impairment
• Monitor for signs of metabolic acidosis
• Evaluate electrolyte levels, particularly calcium

Pregnancy

There is limited data on the safety of ethylene glycol in pregnancy. It should only be used if clearly needed.

Breast-feeding

It is unknown if ethylene glycol is excreted in human milk. Caution is advised.

Storage

Store in a tightly closed container at room temperature, away from heat and moisture.

Formulations

• Liquid

Indications

• Use as a preservative in pharmaceutical formulations
• Antimicrobial agent in cosmetic and food products
• Potential use in the management of inflammatory conditions due to salicylate biosynthesis

Dosage

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

Adults: Refer to the specific product guidelines and BNF for appropriate dosing information.

Mechanism of action

Hydroxybenzoate functions primarily as a preservative by inhibiting the growth of microorganisms. It exerts its effects through the disruption of microbial cell metabolism, thereby preventing spoilage and degradation. The compound is involved in various biosynthetic pathways, including the production of salicylates, which possess anti-inflammatory properties.

Pharmacodynamics

Hydroxybenzoate displays antimicrobial activity against a range of bacteria and fungi. Its efficacy is influenced by factors such as pH and concentration, with higher concentrations generally leading to greater antimicrobial effects. The compound may also exhibit antioxidant properties, contributing to its protective effects in various formulations.

Pharmacokinetics

The pharmacokinetics of hydroxybenzoate involves its absorption, distribution, metabolism, and excretion. It is readily absorbed when applied topically or ingested. Once in the system, it is metabolized primarily in the liver, with metabolites excreted through the urine. The elimination half-life may vary based on the formulation and route of administration.

Pregnancy

There is limited information available regarding the safety of hydroxybenzoate during pregnancy. Consult a healthcare provider for advice.

Breast-feeding

It is unclear if hydroxybenzoate is excreted in human milk. Consult a healthcare provider before use.

Storage

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

Indications

• Babesiosis in animals
• Protozoal infections in veterinary medicine

Dosage

Children: For paediatric dosing, consult the BNF for Children for appropriate recommendations.

Adults: For adults, refer to the specific dosage guidelines as per the BNF.

Mechanism of action

Imidocarb exerts its effects by inhibiting the enzyme dihydrofolate reductase, which is crucial for the synthesis of tetrahydrofolate, a form of folic acid necessary for DNA synthesis and cell division in protozoa. This disruption in folate metabolism leads to impaired nucleic acid synthesis, ultimately resulting in cell death.

Pharmacodynamics

The pharmacodynamics of imidocarb involves its action on protozoal organisms, leading to the inhibition of their growth and replication. The drug is effective against both the asexual and sexual stages of Babesia parasites, providing a therapeutic effect in treating infections. Its selectivity for protozoa over mammalian cells contributes to its therapeutic window.

Pharmacokinetics

Imidocarb is well absorbed after parenteral administration, with peak plasma concentrations occurring within a few hours. It is metabolized in the liver and has a half-life that varies depending on the route of administration and the species treated. The drug is excreted primarily via the urine, with some metabolites also eliminated in the feces. Its pharmacokinetic profile may differ amongst species, necessitating careful consideration when dosing.

Contra-indications

• Hypersensitivity to imidocarb or any of its components.
• History of seizures or epilepsy.
• Pregnancy.

Adverse effects

• Drowsiness.
• Ataxia.
• Vagal stimulation leading to bradycardia.
• Tremors.
• Gastrointestinal upset including vomiting and diarrhea.
• Hypersensitivity reactions including rash.

Interactions

• May enhance the effects of other anticholinergic drugs.
• Concurrent use with cholinesterase inhibitors may antagonize the effects of imidocarb.

Precautions

• Use with caution in patients with liver or kidney impairment.
• Monitor for signs of toxicity, especially in patients with a history of seizures.

Pregnancy

Imidocarb should not be used during pregnancy due to potential risk to the fetus.

Breast-feeding

It is not known if imidocarb is excreted in human milk, caution is advised.

Storage

Store in a cool, dry place, protected from light.

Formulations

• Injectable solution.

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

• Constipation
• Bowel preparation prior to surgical procedures or diagnostic tests

Dosage

Children: Refer to specific guidelines or BNF for Children for dosing information.

Adults: Refer to specific guidelines or BNF for detailed dosing information.

Mechanism of action

Polyethylene glycol works by osmotically retaining water in the intestinal lumen, which increases the water content of the stool. This enhances the passage of stool through the intestines and promotes bowel movements. The high molecular weight of polyethylene glycol prevents its absorption in the gastrointestinal tract, ensuring that it remains in the lumen to exert its effects.

Pharmacodynamics

The pharmacodynamic profile of polyethylene glycol involves its ability to increase stool water content, thereby reducing stool consistency and facilitating easier passage. It does not stimulate intestinal motility directly but rather relies on the osmotic effect to promote bowel evacuation. The onset of action typically occurs within 24 to 96 hours after ingestion.

Pharmacokinetics

Polyethylene glycol is not absorbed systemically, and its pharmacokinetics are characterized by its presence solely in the gastrointestinal tract. It is excreted unchanged in the stool. The volume of polyethylene glycol administered can influence the effectiveness and timing of its action, but its absorption is negligible, making systemic side effects rare.

Adverse effects

• Abdominal cramping
• Diarrhea
• Nausea
• Vomiting
• Bloating
• Flatulence

Precautions

• Use with caution in patients with gastrointestinal disorders or bowel obstruction.
• Ensure adequate hydration during use to prevent dehydration.

Pregnancy

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

Breast-feeding

Polyethylene glycol is excreted in breast milk in very small amounts and is generally regarded as safe during breastfeeding.

Storage

Store at room temperature, away from moisture and heat.

Formulations

• Powder for oral solution
• Liquid formulation

Indications

• Used as a solvent for pharmaceuticals
• Humectant in topical preparations
• Preservative in food and cosmetic products

Dosage

Children: Pediatric dosing should be carefully determined based on formulation and clinical need. It is important to refer to established guidelines or consult a healthcare professional.

Adults: Dosage varies based on formulation and intended use. Refer to specific product guidelines for appropriate dosing.

Mechanism of action

Propylene glycol functions primarily as a solvent and humectant. It facilitates the absorption of drugs, enhancing their bioavailability. Additionally, it may modulate the release of active ingredients from formulations, allowing for extended efficacy. Propylene glycol can also affect the permeability of cell membranes, thereby influencing drug pharmacokinetics.

Pharmacodynamics

Propylene glycol exhibits low toxicity and is generally recognized as safe (GRAS) by the FDA. It has a low molecular weight and high water solubility, which contribute to its ability to penetrate biological membranes. The substance maintains moisture in formulations, impacting the release and absorption profiles of co-formulated drugs.

Pharmacokinetics

Propylene glycol is rapidly absorbed when ingested or applied topically. It is distributed throughout body fluids and tissues, with a volume of distribution that reflects its hydrophilic nature. Metabolism primarily occurs in the liver, where it is converted into lactic acid and subsequently excreted via urine. The half-life of propylene glycol can vary depending on the route of administration and individual metabolic rates.

Pregnancy

Safety during pregnancy has not been established. Use only if the potential benefit justifies the potential risk to the fetus.

Breast-feeding

It is unknown if this drug is excreted in human milk. Caution should be exercised when administered to a nursing woman.

Storage

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

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)

Mechanism of action

Ethylene glycol is metabolized by alcohol dehydrogenase to glycoaldehyde, which is then metabolized to glycolic, glyoxylic, and oxalic acids. These acids, along with excess lactic acid are responsible for the anion gap metabolic acidosis. Oxalic acid readily precipitates with calcium to form insoluble calcium oxalate crystals. Tissue injury is caused by widespread deposition of oxalate crystals and the toxic effects of glycolic and glyoxylic acids.