Chloramphenicol, like other potent drugs, should be prescribed at recommended doses known to have therapeutic activity. Inhibition of the majority of sensitive organisms may be expected at concentrations of 5 to 20 mcg/ml. The desired concentration of active drug in serum should fall within this range over most of the treatment period. Dosage of 50 mg/kg/day divided into 4 doses at intervals of 6 hours will usually achieve and sustain levels of this order.

Except in certain circumstances (e.g. premature infants and neonates and individuals with hepatic or renal impairment) lower doses may not achieve these concentrations. Close observation of the patient should be maintained and in the event of any adverse reactions, dosage should be reduced or the drug discontinued, if other factors in the clinical situation permit.

Adults: should receive 50 mg/kg/day in divided doses [approximately one 250 mg capsule per each 4.5 kg (10 lbs) of body weight or one 500 mg capsule per each 9 kg (20 lbs) of body weight] in divided doses at 6 hour intervals. In exceptional cases, patients with infections due to moderately resistant organisms may require increased dosage up to 100 mg/kg/day to achieve serum levels inhibiting the pathogen, but these high doses should be decreased as soon as possible.

Adults with impairment of hepatic or renal function, or both, may have reduced ability to metabolize and excrete the drug. In instances of impaired metabolic processes, dosages should be adjusted accordingly.

Pediatric patients: Dosage of 50 mg/kg/day divided at 6 hour intervals is effective against most susceptible organisms. Severe infections (eg., bacteremia or meningitis), especially when adequate cerebrospinal fluid concentrations are desired, may require dosage up to 100 mg/kg/day; however, it is recommended that dosage be reduced to 50 mg/kg/day as soon as possible. Children with impaired hepatic or renal function may retain excessive amounts of the drug.

Newborn infants: A total of 25 mg/kg/day in 4 equal doses at 6-hour intervals usually produces and maintains concentrations in serum and tissues adequate to control most infections for which the drug is indicated.