Chloramphenicol, a broad - spectrum antibiotic, is bacteriostatic.
However, it may be bactericidal in high concentrations or when used against highly susceptible organisms.
Chloramphenicol, which is lipid soluble, diffuses through the bacterial cell membrane and reversibly binds to the 50 S 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 should be reserved for serious infections in which less toxic antibacterials are ineffective or contraindicated.
Treatment: Brain abscess - Ehrlichiosis - Meningitis - Paratyphoid fever - Q fever - Rocky mountain spotted fever - Typhoid fever - Typhus infections.

Risk - benefit should be considered when the following medical problems exist:
Bone marrow depression (chloramphenicol may cause a dose - related bone marrow depression, an idiosyncratic aplastic anemia, and other blood dyscrasias) - Hepatic or renal function impairment. ln patients who have had previous cytotoxic drug therapy or radiation therapy also.

Chloramphenicol readily crosses the placenta; fetal serum concentrations may be 30 to 80% of maternaI serum concentrations.
Although birth defects in humans have not been documented, use is not recommended in pregnancy at term or during labor because of potential toxicity ("gray syndrome" or bone marrow depression) in premature or full term infants.
Chloramphenicol is excreted in breast milk in concentrations up to 25 mcg per mL. Use is not recommended in nursing mothers because of the possibility of adverse effects, especially bone marrow depression, in the infant.

Combinations containing any of the following medications,depending on the amount present, may also interact with this medication:
Alfentanil - Anticonvulsants, hydantoin - Bone marrow depressants - Radiation therapy -Antidiabetic agents - Contraceptives, estrogen containing, oral - Clindamycin - Erythromycins - Lincomycin - Hepatic enzyme inducers - Penicillins - Phenobarbital - Phenytoin - Warfarin - Other medications metabolized by mixed function oxidase system - Vitamin B₁₂.

Aplastic anemia is an idiosyncratic reaction that occurs in 1 of every 25,000 to 40,000 courses of treatment.
Those indicating need for medical attention: Incidence less frequent: Blood dyscrasias.
Incidence rare: Gray syndrome, hypersensitivity reactions, neurotoxic reactions, optic neuritis, peripheral neuritis.

Capsules and oral suspension: Usual adult and adolescent dose:
Antibacterial - Oral, 12.5 mg (base) per kg of body weight every 6 hours.
Usual adult prescribing limits: Up to maximum of 4 grams (base) daily.
Usual pediatric dose: Antibacterial - Premature and full - term infants up to 2 weeks of age: Oral, 6.25 mg (base) per kg of body weight every 6 hours. Infants 2 weeks of age and over: Oral, 12.5 mg (base) per kg of body weight every 6 hours; or 25 mg per kg of body weight every 12 hours.