CHLOROMYCETIN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for CHLOROMYCETIN (CHLOROMYCETIN).
Inhibits bacterial protein synthesis by binding to the 50S ribosomal subunit, preventing peptide bond formation.
| Metabolism | Primarily hepatic metabolism via glucuronidation; major metabolite is chloramphenicol glucuronide. |
| Excretion | Renal: 5-10% unchanged; hepatic glucuronidation (90%) followed by renal elimination of metabolites; small biliary excretion (<5%) and fecal elimination. |
| Half-life | 1.5-4 hours in adults; prolonged to 3-7 hours in neonates and 4-12 hours in hepatic impairment; clinical context: dose adjustment required in liver disease. |
| Protein binding | 50-60% bound primarily to albumin; binding is reversible and saturable at high concentrations. |
| Volume of Distribution | 0.6-1.0 L/kg; indicates extensive tissue distribution; penetrates well into CSF, brain, and ocular tissues; clinically relevant for CNS infections. |
| Bioavailability | Oral: 75-90% (chloramphenicol palmitate); topical ophthalmic: limited systemic absorption; IV: 100%. |
| Onset of Action | IV: 30-60 minutes; oral: 1-2 hours; topical ophthalmic: 15-30 minutes; for systemic infections, clinical response within 24-48 hours. |
| Duration of Action | IV: 6-8 hours; oral: 6-8 hours; topical: 4-6 hours; duration is dose-dependent; monitor for bone marrow suppression with prolonged use. |
| Action Class | Chloramphenicol |
| Brand Substitutes | Biophenicol 500mg Capsule, Daclor 500mg Capsule, Kemicetine 500mg, Chlorocin 500mg Capsule, Ochlor 500mg Capsule, Armycetin Capsule, Entechlor 250mg Capsule, Radixin 250mg Capsule, Synophen 250mg Capsule, Gravomycetin 250mg Capsule, Fencol 125mg/5ml Suspension, Chloraxin 125mg/5ml Suspension, Phenicol 125mg/5ml Suspension, Chemocetin 125mg Suspension, Wocol 125mg/5ml Suspension |
50-100 mg/kg/day IV divided every 6 hours; maximum 4 g/day. Topical: apply to affected area 2-4 times daily.
| Dosage form | INJECTABLE |
| Renal impairment | No specific dosing adjustment required for renal impairment; however, monitor for dose-related toxicity. For severe renal failure (eGFR <10 mL/min/1.73m²), consider dose reduction to 1 g/day. |
| Liver impairment | Child-Pugh A: No adjustment. Child-Pugh B: Reduce dose by 50% and monitor serum concentrations. Child-Pugh C: Avoid use or reduce dose by 75% with therapeutic drug monitoring. |
| Pediatric use | Neonates: 12.5-25 mg/kg IV every 6 hours; monitor serum concentrations (target peak 15-25 mcg/mL, trough 5-10 mcg/mL). Children: 12.5-25 mg/kg IV every 6 hours; maximum 4 g/day. |
| Geriatric use | No specific dose adjustment; caution due to age-related decline in hepatic function; monitor for bone marrow suppression and maintain therapeutic drug monitoring. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for CHLOROMYCETIN (CHLOROMYCETIN).
| Breastfeeding | Chloramphenicol is excreted into breast milk with a milk to plasma ratio of approximately 0.5. Concentrations in milk are low (<0.5 μg/mL), but there is a potential risk of bone marrow suppression and idiosyncratic aplastic anemia in the nursing infant. The American Academy of Pediatrics recommends avoiding use during breastfeeding due to the risk of serious adverse effects. |
| Teratogenic Risk | Chloramphenicol crosses the placenta. First trimester: Limited data, but grey baby syndrome reported with high doses near term. Second trimester: No specific teratogenic effects documented, but avoid due to risk of bone marrow suppression. Third trimester: Avoid near delivery due to risk of grey baby syndrome (cardiovascular collapse, cyanosis, death) and bone marrow suppression in neonate. |
■ FDA Black Box Warning
Serious and fatal blood dyscrasias (aplastic anemia, hypoplastic anemia, thrombocytopenia, granulocytopenia) have been reported. Chloramphenicol should not be used for trivial infections or when less toxic agents are effective.
| Serious Effects |
History of hypersensitivity to chloramphenicol; known prior myelosuppression; concurrent use with bone marrow depressants.
| Precautions | Bone marrow suppression; monitor complete blood counts regularly; avoid in neonates (gray baby syndrome); potential for pseudomembranous colitis; drug interactions with oral anticoagulants, phenytoin, and sulfonylureas. |
| Food/Dietary | Avoid alcohol and any products containing alcohol (mouthwash, cough syrups) due to risk of disulfiram-like reaction (flushing, nausea, vomiting, headache). No other specific food interactions. |
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| Fetal Monitoring | Monitor maternal complete blood count (CBC) with differential and platelet count every 2-3 days to detect bone marrow suppression. Monitor serum drug concentrations (therapeutic range 10-20 μg/mL for peak, 5-10 μg/mL for trough) to avoid toxicity. In pregnancy, monitor fetal growth and well-being with ultrasound if prolonged therapy. Monitor neonate for signs of grey baby syndrome (vomiting, lethargy, cyanosis, hypothermia, cardiovascular collapse) if used near term. |
| Fertility Effects | Chloramphenicol has been associated with reversible suppression of spermatogenesis in animal studies. Human data limited, but potential for transient reduction in sperm count. No reported effects on female fertility. |
| Clinical Pearls | Chloramphenicol can cause dose-dependent bone marrow suppression and rare but fatal aplastic anemia; reserve for serious infections without safer alternatives. Monitor CBCs closely, especially with prolonged therapy. Use with caution in neonates (gray baby syndrome) due to immature hepatic glucuronidation. Drug interactions: inhibits CYP2C9 and CYP3A4; increases effect of warfarin, phenytoin, sulfonylureas. |
| Patient Advice | Take exactly as prescribed; do not stop early even if you feel better. · Report unexplained bruising, bleeding, sore throat, or fever immediately (signs of bone marrow suppression). · Avoid alcohol during treatment and for 48 hours after (disulfiram-like reaction). · Tell your doctor if you are pregnant, breastfeeding, or have liver disease. · Complete the full course to prevent resistance. |