Chloromycetin (chloramphenicol) is a bacteriostatic antibiotic with a well-established history in clinical practice, valued for its broad-spectrum activity against a wide range of Gram-positive and Gram-negative bacteria, as well as certain other microorganisms. It functions by inhibiting bacterial protein synthesis, binding to the 50S ribosomal subunit and preventing peptide bond formation. While its systemic use is now reserved for serious infections due to potential hematologic toxicity, its topical and ophthalmic formulations remain widely utilized. This agent is particularly significant in settings where other antibiotics are ineffective or contraindicated, underscoring its role as an essential therapeutic option in specific clinical scenarios.

Features

• Active ingredient: Chloramphenicol
• Available formulations: Oral capsules, ophthalmic solutions/ointments, topical creams
• Mechanism: Inhibits bacterial protein synthesis at the 50S ribosomal subunit
• Spectrum: Broad activity against Gram-positive, Gram-negative, anaerobic bacteria, and Rickettsia
• Prescription status: Requires medical prescription in most jurisdictions

Benefits

• Effective against multidrug-resistant organisms where other antibiotics fail
• Rapid bacteriostatic action leading to prompt symptomatic relief in susceptible infections
• Multiple administration routes allow targeted therapy (systemic, topical, ophthalmic)
• Well-established efficacy in typhoid fever and other serious systemic infections
• Cost-effective alternative in resource-limited settings for specific indications
• High tissue penetration, including central nervous system, making it valuable for meningitis

Common use

Chloromycetin is primarily indicated for serious infections caused by susceptible organisms when less potentially dangerous agents are ineffective or contraindicated. Systemic administration is reserved for life-threatening infections such as typhoid fever, bacterial meningitis, Rickettsial diseases, and other severe infections where the benefit outweighs the risk of potential hematologic toxicity. Topical formulations are commonly used for superficial eye infections (conjunctivitis, blepharitis), external ear infections, and skin infections. Ophthalmic preparations are particularly valuable for treating purulent bacterial conjunctivitis and corneal ulcers.

Dosage and direction

Dosage varies significantly based on formulation, infection severity, patient age, and renal/hepatic function. For systemic administration in adults: 50 mg/kg/day in divided doses every 6 hours for serious infections, not to exceed 4 g daily. Pediatric dosing: 50-75 mg/kg/day in divided doses every 6 hours. For ophthalmic use: Apply 1-2 drops to affected eye(s) every 3-6 hours, or a small amount of ointment into the conjunctival sac every 3-6 hours. Topical applications should be applied to clean, affected areas 1-4 times daily. Duration of treatment should be the shortest possible to achieve clinical cure, typically 7-14 days for systemic therapy. Complete the full course even if symptoms improve earlier.

Precautions

Regular monitoring of complete blood counts is mandatory during systemic therapy due to risk of bone marrow suppression, including potentially fatal aplastic anemia. Use with caution in patients with hepatic or renal impairment, requiring dosage adjustment. Avoid unnecessary use; reserve for serious infections where alternatives are unsuitable. Pregnancy Category C: use only if potential benefit justifies potential risk to fetus. Nursing mothers should avoid breastfeeding during treatment as chloramphenicol excretes in breast milk. Monitor for superinfection or fungal overgrowth. Genetic counseling recommended for patients with family history of blood dyscrasias.

Contraindications

Hypersensitivity to chloramphenicol or any component of the formulation. History of chloramphenicol-induced blood dyscrasias. Avoid concurrent use with other bone marrow suppressants. Contraindicated in prophylactic use for trivial infections. Not recommended for treatment of minor infections, colds, influenza, or throat infections. Avoid in patients with known glucose-6-phosphate dehydrogenase deficiency due to risk of hemolytic anemia. Contraindicated in infants under 2 years for systemic administration except in life-threatening situations where alternatives are unavailable (gray baby syndrome risk).

Possible side effect

Hematologic: Bone marrow suppression, aplastic anemia, granulocytopenia, thrombocytopenia Gastrointestinal: Nausea, vomiting, diarrhea, glossitis, stomatitis Neurologic: Headache, mild depression, confusion, optic neuritis Hypersensitivity reactions: Rash, fever, angioedema Other: Gray baby syndrome (in neonates), peripheral neuritis, blurred vision (with ophthalmic use) Superinfections: Fungal overgrowth, Clostridium difficile-associated diarrhea

Drug interaction

Warfarin: Enhanced anticoagulant effect, increased bleeding risk Phenytoin: Increased phenytoin levels, risk of toxicity Sulfonylureas: Enhanced hypoglycemic effect Cyclophosphamide: Reduced activation, decreased efficacy Vitamin B12: Impaired response to hematinic therapy Barbiturates: Reduced chloramphenicol efficacy, increased barbiturate metabolism Oral contraceptives: Possible reduced contraceptive efficacy Alcohol: Disulfiram-like reaction possible

Missed dose

If a dose is missed, take it as soon as remembered unless it is almost time for the next scheduled dose. Do not double the dose to make up for the missed one. For ophthalmic/topical formulations, apply the missed dose when remembered and resume regular schedule. Maintaining consistent antibiotic levels is crucial for efficacy, particularly with systemic administration. If multiple doses are missed, contact healthcare provider for guidance on resuming therapy.

Overdose

Systemic overdose may cause nausea, vomiting, gray cyanosis, cardiovascular collapse, and bone marrow suppression. In infants, gray baby syndrome characterized by abdominal distension, cyanosis, vasomotor collapse. Treatment is supportive: gastric lavage if recent ingestion, activated charcoal, and symptomatic management. Hemodialysis is ineffective due to high protein binding. Monitor blood counts frequently for several weeks post-overdose. For topical/ophthalmic overdose, rinse affected area with water and seek medical attention if symptoms persist.

Storage

Store at controlled room temperature (15-30°C). Protect from light and moisture. Keep oral capsules in tightly closed container. Ophthalmic solutions should be stored upright and discarded 28 days after opening. Do not freeze. Keep all medications out of reach of children and pets. Do not use beyond expiration date. Do not transfer between containers. Store away from heat sources and direct sunlight.

Disclaimer

This information is for educational purposes only and does not constitute medical advice. Chloromycetin is a potent antibiotic with serious potential side effects and must be used only under direct medical supervision. The prescribing physician must carefully weigh benefits against risks, particularly regarding hematologic toxicity. Always follow your healthcare provider’s instructions regarding dosage, administration, and monitoring. Do not self-medicate or share this medication with others. Report any adverse effects to your physician immediately.

Reviews

“Chloromycetin remains an invaluable agent in our infectious disease arsenal, particularly for multidrug-resistant Salmonella typhi infections. While we respect its toxicity profile, when used appropriately with careful monitoring, it saves lives where other antibiotics fail.” - Infectious Disease Specialist, 15 years experience

“As an ophthalmologist, I find chloramphenicol ophthalmic ointment exceptionally effective for bacterial conjunctivitis. Its broad spectrum coverage and good corneal penetration make it a first-line choice in many cases, though we remain vigilant about potential resistance development.” - Ophthalmologist, 12 years experience

“The hematologic monitoring requirements make systemic chloramphenicol challenging to use in outpatient settings, but in hospitalized patients with appropriate monitoring, it can be life-saving for certain CNS infections and rickettsial diseases.” - Clinical Pharmacist, 8 years experience