Comycetin eye drops

Indications

• Bacterial infections
• Typhoid fever
• Severe bacterial eye infections
• Bacterial meningitis

Mechanism of action

Chloramphenicol diffuses through the bacterial cell membrane due to its lipid solubility. It reversibly binds to the L16 protein of the 50S subunit of bacterial ribosomes, inhibiting the transfer of amino acids to growing peptide chains by suppressing peptidyl transferase activity. This action prevents peptide bond formation and thus protein synthesis. In addition, chloramphenicol can inhibit mitochondrial protein synthesis in mammalian cells, as mitochondrial ribosomes resemble bacterial ribosomes more than they do mammalian cytoplasmic ribosomes.

Pharmacodynamics

Chloramphenicol is classified as a bacteriostatic antibiotic, meaning it inhibits the growth of bacteria rather than killing them directly. However, at high concentrations or against particularly susceptible organisms, it can exhibit bactericidal properties. The drug is effective against a variety of pathogens, making it useful for treating serious infections. Due to its side effects, particularly hematologic toxicity, chloramphenicol is used cautiously and is often restricted to life-threatening infections where other treatments are not appropriate.

Pharmacokinetics

Chloramphenicol is well-absorbed after oral administration and can penetrate tissues and body fluids, including the central nervous system, making it effective for treating infections in various sites. It is metabolized in the liver, and its elimination half-life can be prolonged in individuals with hepatic impairment. The drug is also excreted in urine, primarily as metabolites, but some unchanged drug may also be present. Dose adjustments may be necessary in cases of liver and kidney impairment to avoid toxicity.

Contra-indications

• Children under 12 years
• Pregnant women
• Patients with a history of cholestasis

Adverse effects

• Agranulocytosis
• Aplastic anaemia
• Nephritis
• Renal impairment
• Gastrointestinal discomfort
• Decreased appetite
• Diarrhoea
• Dizziness
• Toxic epidermal necrolysis
• Hepatotoxicity
• Stomatitis

Interactions

• Chloramphenicol + Guanfacine: Unknown (increases exposure)
• Chloramphenicol + Iron: Unknown (decreases efficacy)
• Chloramphenicol + Sulfonylureas: Unknown (increases exposure)
• Chloramphenicol + Tacrolimus: Unknown (increases concentration)
• Rifampicin + Chloramphenicol: Unknown (decreases concentration)

Precautions

• Caution in hepatic impairment
• Caution in renal impairment
• Use in high doses with caution due to risk of hepatotoxicity
• Monitor for signs of bone marrow suppression

Pregnancy

Chloramphenicol should not be given to pregnant women due to risks of effects on skeletal development and potential for discoloration of the child's teeth. Use only if potential benefit outweighs risk.

Breast-feeding

Manufacturer advises avoiding use during breastfeeding as it is present in milk and may pose risks to the infant.

Storage

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

Formulations

• Tablet
• Capsule
• Oral solution
• Powder for solution for infusion

Indications

• Topical antifungal treatment
• Treatment of yeast infections
• Disinfectant for minor cuts and abrasions

Dosage

Children: Refer to specific product guidelines or medical literature as dosages can vary based on formulation and indication.

Adults: Refer to specific product guidelines or medical literature as dosages can vary based on formulation and indication.

Mechanism of action

Information regarding the mechanism of action of boric acid in mediating its antibacterial or antifungal actions is limited. Boric acid inhibits biofilm formation and hyphal transformation of Candida albicans, which are critical virulence factors. In addition, arrest of fungal growth was observed with the treatment of boric acid.

Pharmacodynamics

Boric acid exhibits minimal bacteriostatic and antifungal activities. It is likely to mediate antifungal actions at high concentrations over prolonged exposures. The effectiveness of boric acid as a topical agent depends on the concentration and duration of exposure to the target organism.

Pharmacokinetics

The pharmacokinetics of borax are not extensively documented. However, it is known that borax is poorly absorbed when ingested orally, and its effects are primarily local when applied topically. Systemic absorption can occur, but this is generally minimal. Boron, the active component in borax, may accumulate in body tissues with prolonged exposure, although specific details regarding the distribution, metabolism, and excretion of borax remain limited.

Pregnancy

Boric acid should be used with caution during pregnancy. Consult a healthcare professional before use.

Breast-feeding

Use of boric acid while breastfeeding is not well established. Consult a healthcare professional.

Storage

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

Indications

• Vulvovaginal candidiasis
• Fungal infections
• Antiseptic for minor cuts and abrasions
• Ocular antiseptic
• Insecticide in pest control

Dosage

Adults: Refer to specific guidelines for formulations. Commonly used as a 2-3% solution

Mechanism of action

Boric acid exerts its antifungal effects by disrupting the cell membrane integrity of fungi. It interferes with the synthesis of essential cellular components, leading to cell lysis and death. The acid also has mild antibacterial properties, which can help in reducing bacterial load in infected areas. The exact molecular pathways involved in these actions are not fully elucidated, but it is known to alter the pH of the environment, making it less conducive for fungal growth.

Pharmacodynamics

Boric acid demonstrates a low toxicity profile in humans when used appropriately. Its antifungal activity is primarily effective against Candida species, and it can be used as a second-line treatment for vulvovaginal candidiasis, particularly in cases of recurrent infections. The effectiveness of boric acid is also attributed to its ability to maintain an acidic environment, which is unfavorable for the growth of many pathogens. Its antiseptic properties help in reducing inflammation and promoting healing in infected tissues.

Pharmacokinetics

Boric acid is poorly absorbed through the gastrointestinal tract but can be absorbed through the skin and mucous membranes. Once absorbed, it is distributed throughout the body, with a tendency to accumulate in various tissues, including the liver and kidneys. The elimination half-life of boric acid is variable, depending on dosage and route of administration. It is primarily excreted unchanged in the urine. Due to its potential for toxicity with high systemic exposure, it is important to adhere to recommended dosages.

Contra-indications

• Hypersensitivity to boron or any component of the formulation
• Severe renal impairment

Adverse effects

• Skin irritation or rash
• Nausea
• Vomiting
• Diarrhea
• Headache
• Fatigue
• Tremors
• Confusion

Interactions

• May interact with other topical medications
• Caution with nephrotoxic agents

Precautions

• Use with caution in patients with renal insufficiency
• Careful monitoring is advised in long-term use
• Not recommended for use in large areas of broken skin

Pregnancy

Boric acid is classified as category C. Use during pregnancy only if the potential benefit justifies the potential risk to the fetus.

Breast-feeding

Limited data available. It is advisable to avoid use while breastfeeding.

Storage

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

Formulations

• Topical ointment
• Powder
• 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

• 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.

Mechanism of action

Chloramphenicol is lipid-soluble, allowing it to diffuse through the bacterial cell membrane. It then reversibly binds to the L16 protein of the 50S subunit of bacterial ribosomes, where transfer of amino acids to growing peptide chains is prevented (perhaps by suppression of peptidyl transferase activity), thus inhibiting peptide bond formation and subsequent protein synthesis. Chloramphenicol inhibits protein synthesis in bacteria, and to a lesser extent, in eukaryotic cells. The drug readily penetrates bacterial cells, probably by facilitated diffusion. Chloramphenicol acts primarily by binding reversibly to the 50S ribosomal subunit (near the binding site for the macrolide antibiotics and clindamycin, which chloramphenicol inhibits competitively). Although binding of tRNA at the codon recognition site on the 30S ribosomal subunit is undisturbed, the drug apparently prevents the binding of the amino acid-containing end of the aminoacyl tRNA to the acceptor site on the 50S ribosomal subunit. The interaction between peptidyltransferase and its amino acid substrate cannot occur, and peptide bond formation is inhibited. Chloramphenicol ... can inhibit mitochondrial protein synthesis in mammalian cells, perhaps because mitochondrial ribosomes resemble bacterial ribosomes (both are 70S) more than they do the 80S cytoplasmic ribosomes of mammalian cells. The peptidyltransferase of mitochondrial ribosomes, but not of cytoplasmic ribosomes, is inhibited by chloramphenicol. Mammalian erythropoietic cells are particularly sensitive to the drug. /Chloramphenicol/ inhibits bacterial protein synthesis by interfering with the transfer of activated amino acids from soluble RNA to ribosomes. In vitro, chloramphenicol exerts mainly a bacteriostatic effect on a wide range of gram-negative and gram-positive bacteria. /Chloramphenicol/ acts by inhibition of protein synthesis by interfering with the transfer of activated amino acids from soluble RNA to ribosomes. For more Mechanism of Action (Complete) data for Chloramphenicol (9 total), please visit the HSDB record page.

Pharmacodynamics

Chloramphenicol is a broad-spectrum antibiotic that was derived from the bacterium Streptomyces venezuelae and is now produced synthetically. Chloramphenicol is effective against a wide variety of microorganisms, but due to serious side-effects (e.g., damage to the bone marrow, including aplastic anemia) in humans, it is usually reserved for the treatment of serious and life-threatening infections (e.g., typhoid fever). Chloramphenicol is bacteriostatic but may be bactericidal in high concentrations or when used against highly susceptible organisms. Chloramphenicol stops bacterial growth by binding to the bacterial ribosome (blocking peptidyl transferase) and inhibiting protein synthesis.

Mechanism of action

Information regarding the mechanism of action of boric acid in mediating its antibacterial or antifungal actions is limited. Boric acid inhibits biofilm formation and hyphal transformation of _Candida albicans_, which are critical virulence factors. In addition, arrest of fungal growth was observed with the treatment of boric acid.

Pharmacodynamics

Boric acid exhibits minimal bacteriostatic and antifungal activities. Boric acid is likely to mediate antifungal actions at high concentrations over prolonged exposures.