ABCHLOR EAR 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

• Historically used as a disinfectant
• Antiseptic
• Treatment of certain infections (now largely abandoned due to toxicity)

Dosage

Children: Specific dosing is not provided due to safety concerns and the potential for toxicity. Refer to appropriate clinical guidelines for dosing if applicable.

Adults: Specific dosing is not provided due to safety concerns and the potential for toxicity. Refer to appropriate clinical guidelines for dosing if applicable.

Mechanism of action

Mercuric compounds exert their effects primarily through the inhibition of sulfhydryl (thiol) groups in proteins and enzymes, leading to disruption of cellular functions. This interaction can affect various biochemical pathways, including those involved in cellular respiration and metabolism.

Pharmacodynamics

The pharmacodynamics of mercuric compounds is characterized by their ability to bind to cellular proteins, leading to alterations in enzymatic activity and disruption of cellular homeostasis. The toxic effects manifest in various organ systems, particularly the kidneys, nervous system, and gastrointestinal tract. Symptoms of mercury toxicity include tremors, memory loss, neuromuscular effects, and renal impairment.

Pharmacokinetics

Mercuric compounds are poorly absorbed from the gastrointestinal tract, but once absorbed, they can distribute widely throughout the body, accumulating in the kidneys, liver, and brain. The half-life of mercury in the body is prolonged, ranging from weeks to months, depending on the compound and individual factors. Excretion primarily occurs via the kidneys, with a small amount eliminated through feces and exhalation.

Contra-indications

• Hypersensitivity to mercuric compounds
• Severe renal impairment
• Active gastrointestinal disease

Adverse effects

• Nephrotoxicity
• Gastrointestinal disturbances (nausea, vomiting, diarrhea)
• Neurological effects (tremors, mood changes, cognitive impairment)
• Dermatitis
• Allergic reactions
• Hematological effects (anemia, leukopenia)

Interactions

• May interact with other nephrotoxic agents, increasing the risk of kidney damage
• Chelating agents like dimercaprol may be used in cases of poisoning but should be used cautiously

Precautions

• Use with caution in patients with pre-existing renal disease
• Monitor renal function regularly during treatment
• Avoid exposure in occupational settings due to potential for toxicity

Pregnancy

Mercuric compounds are contraindicated during pregnancy due to potential fetal toxicity and teratogenic effects.

Breast-feeding

Mercuric compounds should be avoided during breastfeeding due to the risk of excretion in breast milk and potential harm to the nursing infant.

Storage

Store in a tightly closed container, protected from light, at room temperature, away from moisture and incompatible substances.

Formulations

• Mercuric chloride
• Mercuric iodide
• Mercuric sulfide

Indications

• Pain relief
• Inflammation reduction
• Fever reduction
• Various therapeutic applications depending on specific phenyl-containing compounds

Dosage

Children: Refer to BNF for Children for dosage recommendations.

Adults: Refer to specific phenyl-containing compound for dosage recommendations.

Mechanism of action

Compounds containing the phenyl group often act by modulating neurotransmitter pathways, inhibiting cyclooxygenase enzymes, or interacting with various receptor sites, depending on the specific drug structure. For example, phenyl-containing analgesics may work by blocking the synthesis of prostaglandins, thus reducing pain and inflammation.

Pharmacodynamics

The pharmacodynamics of phenyl-containing compounds vary widely based on the specific drug, but many exhibit effects such as analgesia, anti-inflammatory activity, or antipyretic properties. The phenyl group can enhance lipophilicity, allowing for better absorption and distribution in the body.

Pharmacokinetics

The pharmacokinetics of phenyl-containing compounds are dependent on their chemical structure. Generally, these compounds have varied absorption rates, metabolism predominantly through hepatic pathways, and excretion primarily via renal mechanisms. The presence of the phenyl group can influence the half-life and bioavailability of the drug.

Pregnancy

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

Breast-feeding

It is not known whether phenyl is excreted in human milk. Caution should be exercised when administered to a nursing mother.

Storage

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

Indications

• Nutritional supplementation
• Metabolic disorders
• Potential use in energy metabolism enhancement

Dosage

Children: Refer to the BNF for Children for appropriate dosing information as it may vary based on indication and formulation.

Adults: Refer to specific clinical guidelines or consult the BNF for appropriate dosing information as it may vary based on indication and formulation.

Mechanism of action

Phenylpropionate is primarily involved in metabolic processes. It may exert its effects through modulation of fatty acid metabolism and energy homeostasis. Specific pathways include the involvement in β-oxidation and potential interactions with peroxisome proliferator-activated receptors (PPARs), which regulate gene expression related to lipid metabolism.

Pharmacodynamics

Phenylpropionate exhibits properties that can influence lipid metabolism and energy utilization within the body. Its effects on fatty acid oxidation can lead to alterations in energy expenditure. The pharmacodynamic profile is characterized by its ability to impact metabolic pathways, although detailed receptor interactions remain less defined.

Pharmacokinetics

The pharmacokinetic properties of phenylpropionate, including absorption, distribution, metabolism, and excretion, have not been extensively documented in the available literature. As a carboxylic acid derivative, it is likely absorbed through the gastrointestinal tract, metabolized primarily in the liver, and excreted via the kidneys. Further studies would be needed to define specific parameters such as half-life and bioavailability.

Pregnancy

There is insufficient data on the safety of phenylpropionate in pregnancy. It should only be used if the potential benefit justifies the potential risk to the fetus.

Breast-feeding

Caution should be exercised when phenylpropionate is administered to a nursing mother. The effects on the breastfeeding infant are not well studied.

Storage

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