Antimicrobial Activity

Chloramphenicol binds to the 50S subunit of ribosomes and inhibits protein synthesis. While active against S pneumoniae, H influenzae, and Neisseria meningitidis, it is used minimally because of its toxicity and the availability of alternative agents. Chloramphenicol is active against certain rickettsiae.

Pharmacokinetics & Administration

Chloramphenicol is widely distributed in tissues, including the eye and cerebrospinal fluid. Chloramphenicol is metabolized in the liver, and < 10% is excreted unchanged in the urine. Thus, no dosage adjustment is needed in kidney disease. Patients with liver disease may accumulate the drug, and levels should be monitored.

Clinical Uses

Chloramphenicol is an occasional alternative to more standard therapy for (1) meningococcal, H influenzae, or pneumococcal infections of the central nervous system; (2) anaerobic or mixed infections in the central nervous system, eg, brain abscess; (3) as an alternative to tetracyclines in rickettsial infections, especially in pregnant women, in whom tetracycline is contraindicated.

Adverse Effects

Chloramphenicol in excess of 50 mg/kg/d regularly causes reversible disturbances in red cell maturation within 1–2 weeks. In contrast, it is also associated with an irreversible aplastic anemia in 1:40,000–1:25,000 courses of chloramphenicol treatment.