Chloramphenicol is a broad-spectrum bacteriostatic antibiotic originally derived from *Streptomyces venezuelae*. It is a potent inhibitor of bacterial protein synthesis. Due to its association with serious and potentially fatal adverse effects, most notably dose-independent irreversible bone marrow aplasia (aplastic anemia) and the 'Gray Baby Syndrome' in neonates, its use in clinical practice is now highly restricted. In India, it is reserved for the treatment of severe, life-threatening infections where safer alternatives are ineffective, contraindicated, or unavailable, particularly those caused by multidrug-resistant organisms like *Salmonella typhi* (typhoid fever) and *Haemophilus influenzae* (meningitis).
Adult: Oral/IV: 50-100 mg/kg/day in divided doses every 6 hours. For severe infections (e.g., meningitis, typhoid): Up to 4-6 grams per day in divided doses. Typical 500mg capsule dose: 1-2 capsules every 6 hours. MUST NOT EXCEED MAXIMUM DOSE.
Note: Oral: Take on an empty stomach (1 hour before or 2 hours after meals) for optimal absorption, but can be taken with food to reduce GI upset. Capsule should be swallowed whole with a full glass of water. IV: Administer as a slow intravenous infusion over at least 15-30 minutes. NEVER GIVE INTRAVENOUSLY AS A BOLUS. Complete the prescribed course even if feeling better.
Chloramphenicol binds reversibly to the 50S subunit of the bacterial 70S ribosome. This binding inhibits the peptidyl transferase activity, thereby preventing the transfer of the growing peptide chain to the newly attached aminoacyl-tRNA at the A site. This action blocks the formation of peptide bonds, a critical step in protein synthesis, leading to bacteriostatic inhibition of bacterial growth.
Pregnancy: Category C (US FDA). Crosses the placenta. Use only if potential benefit justifies the potential fetal risk. Avoid near term due to risk of 'Gray Baby Syndrome' in the newborn.
Driving: May cause dizziness, confusion, or visual disturbances. Patients should be cautioned about driving or operating machinery until their response is known.
| Warfarin, Acenocoumarol | Chloramphenicol inhibits hepatic metabolism of coumarins, potentiating anticoagulant effect leading to increased risk of bleeding. | Major |
| Phenytoin, Phenobarbital | Chloramphenicol inhibits metabolism of phenytoin/phenobarbital, increasing their levels and risk of toxicity (ataxia, nystagmus). Conversely, these drugs may decrease chloramphenicol levels. | Major |
| Sulfonylureas (e.g., Glibenclamide) | Increased risk of hypoglycemia due to inhibited metabolism. | Moderate |
| Rifampicin | Rifampicin induces chloramphenicol metabolism, decreasing its plasma concentration and efficacy. | Moderate |
| Paracetamol (Acetaminophen) | May increase risk of bone marrow suppression and prolong half-life of chloramphenicol. | Moderate |
| Other Myelosuppressive drugs (e.g., Chemotherapy, Zidovudine) | Additive risk of bone marrow toxicity. | Major |
Same composition (Chloramphenicol (500mg)), different brands: