Chloramphenicol is an antibiotic useful for the treatment of a number of bacterial infections. This includes as an eye ointment to treat conjunctivitis. By mouth or by injection into a vein, it is used to treat meningitis, plague, cholera, and typhoid fever.
Broad spectrum antimicrobial
In vitro, chloramphenicol exerts mainly a bacteriostatic effect on a wide range of Gram-negative and Gram positive bacteria and is active against rickettsiae, the lymphogranuloma-psittacosis group and Vibrio cholerae. It is particularly active against Salmonella typhi and Haemophilus influenzae. The mode of actions is through interference or inhibition of protein synthesis in intact cells and cell-free systems. Antagonism has been demonstrated in vitro between chloramphenicol, erythromycin, clindamycin and lincomycin. Chloramphenicol is rapidly absorbed from the GI tract. Chloramphenicol palmitate is hydrolyzed in the GI tract and is absorbed as free chloramphenicol.
Following oral administration of a single one gram dose of chloramphenicol base to healthy adults, average peak plasma chloramphenicol concentrations of about 11 mcg/ml were attained with 1-3 hours. Cumulative dosing gave a peak of 18 mcg/ml after the fifth dose of one gram, every 6 hours. Mean serum levels were 8-14 mcg/ml over a 48 hour period.
Most of the drug is excreted in the urine. Despite the small proportion of unchanged drug excreted in the urine, the concentration of free chloramphenicol in the urine is relatively high. From 8% to 12% of the antibiotic is excreted as free chloramphenicol. The remainder is excreted as inert metabolites, mainly glucuronate. Small amounts of active drug are found in bile and feces. Chloramphenicol diffuses rapidly, but its distribution is not uniform. Highest concentrations are found in liver and kidney, and lowest concentrations are found in brain and cerebrospinal fluid (CSF). Chloramphenicol enters CSF even in the absence of meningeal inflammation, appearing in concentrations about half of those found in the blood.
ORAL Bacterial meningitis; Brain abscess; Granuloma inguinale; Anthrax; Listeriosis; Gas gangrene; Whipple’s disease; Severe systemic infections wI Camphylobacter fetus; Infections caused by H. influenzae; Ehrlichiosis; Severe gastroenteritis; Severe melioidosis; Plague;Psittacosis; 0 fever; Anaerobic bacterial infections; Tularaemia: Adult: 50 mg/kg/day in 4 divided doses increased to 100 mg/kg/day for meningitis or severe infections due to moderately resistant organisms. Continue treatment after the patient’s temp has norrnalised for a further 4 days in rickettsial disease & 8-10 days in typhoid fever. Child: Premature & full-term neonates: 25 mg/kg/day in 4 divided doses. Full-term infants >2 wk: 50 mg/kg/day in 4 divided doses. Children: 50 mgI kg/day in 4 divided doses increased to 100 mg/kg/day for meningitis or severe infections.
Chloramphenicol has been shown to retard the biotransformation of tolbutamide, phenytoin, and dicoumarol in man. Chloramphenicol should be used with caution if administered concomitantly with lincomycin, clindamycin, or erythromycin. In vitro experiments have demonstrated that binding sites for erythromycin, lincomycin, clindamycin and Chloramphenicol overlap and competitive inhibition may occur. Rifampin therapy can reduce Chloramphenicol concentrations.
History of hypersensitivity or toxic reaction to the drug; pregnancy, lactation; porphyria; parenteral admin for minor infections or as prophylaxis; preexisting bone marrow depression or blood dyscrasias. Impaired renal or hepatic function; premature & full-term neonates. Monitor plasma concentrations to avoid toxicity.
GI symptoms: bleeding; peripheral & optic neuritis, visual impairment, blindness; encephalopathy, confusion, delirium, mental depression, headache. Haemolysis in patients w/ G6PD deficiency. ophth application: Hypersensitivity reactions including rashes, fever & angioedema. Ear drops: Ototoxicity. Bone marrow suppression & irreversible aplastic anaemia. Neutropenia, thrombocytopenia. Grey baby syndrome. Rarely, anaphylaxis.
Chloramphenicol should only be given during pregnancy when benefit outweighs risk. Use near term is considered contraindicated by some experts. Chloramphenicol is excreted into human milk. Adverse effects have been noted in nursing infants, including refusal of the breast, intestinal gas, and heavy vomiting. In addition, there is a theoretic risk of idiosyncratic bone marrow suppression and Gray Syndrome in the infant. For this reason, use of chloramphenicol during lactation is considered to be of concern by the American Academy of Pediatrics and contraindicated by others.
Levels exceeding 25 mcg/ml are frequently considered toxic. Chloramphenicol toxicity can be evidenced by serious hemopoietic effects such as aplastic anemia, thrombocytopenia, leukopenia, as well as increasing serum iron levels, nausea, vomiting and diarrhea. In the case of serious overdosage, charcoal hemoperfusion may be effective in removing Chloramphenicol from plasma. Exchange transfusion is of questionable value following massive overdosage, especially in neonates and infants.
Store in a cool dry place. Keep bottle securely closed. Protect from light.
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