Chloromycetin

Chloromycetin (chloramphenicol) is a time-tested, broad-spectrum bacteriostatic antibiotic with a well-documented history of efficacy against a wide range of serious bacterial infections. Its unique chemical structure allows it to inhibit bacterial protein synthesis by binding to the 50S ribosomal subunit, making it particularly valuable in treating infections caused by susceptible organisms where other antibiotics may fail. While its use is now reserved for severe scenarios due to potential serious adverse effects, it remains a critical agent in the medical arsenal, especially for life-threatening conditions like bacterial meningitis, typhoid fever, and rickettsial diseases when safer alternatives are contraindicated or ineffective. Healthcare providers rely on its potent activity when microbiological sensitivity and clinical judgment support its necessity.

Features

• Active ingredient: Chloramphenicol
• Available forms: Oral capsules, ophthalmic preparations, and intravenous formulations (as sodium succinate ester)
• Mechanism of action: Binds to the 50S subunit of bacterial ribosomes, inhibiting protein synthesis
• Spectrum: Broad-spectrum activity against Gram-positive, Gram-negative, aerobic, and anaerobic bacteria
• Stability: Chemically stable in various formulations but requires protection from light
• Regulatory status: Available by prescription only, with use often restricted to hospital settings or specialist supervision

Benefits

• Effective against multidrug-resistant organisms, including some strains of Salmonella typhi and Haemophilus influenzae
• Excellent tissue penetration, including cerebrospinal fluid, making it invaluable for central nervous system infections
• Bacteriostatic action that is reversible upon discontinuation, allowing host immune mechanisms to contribute to eradication
• Available in multiple formulations to suit systemic and localized infection treatment protocols
• Cost-effective option in resource-limited settings for specific serious infections
• Rapid onset of action, with serum concentrations peaking within 2-3 hours after oral administration

Common use

Chloromycetin is primarily indicated for serious infections where less hazardous antimicrobial agents are ineffective or contraindicated. Its use includes bacterial meningitis caused by H. influenzae, Neisseria meningitidis, or Streptococcus pneumoniae when penicillin cannot be used; typhoid fever (Salmonella typhi) in areas with high resistance rates to other antibiotics; serious rickettsial infections such as Rocky Mountain spotted fever; and other severe infections caused by susceptible organisms including Bacteroides fragilis, Yersinia pestis (plague), and Brucella species. Ophthalmic formulations are used for superficial eye infections involving susceptible bacteria. Its systemic use requires careful patient selection and monitoring due to the risk of bone marrow toxicity.

Dosage and direction

Dosage must be individualized based on severity of infection, susceptibility of the causative organism, and patient factors including hepatic and renal function. For adults with serious infections: 50 mg/kg/day divided every 6 hours, not to exceed 4 g daily. For life-threatening infections (e.g., meningitis): may increase to 75-100 mg/kg/day divided every 6 hours. Pediatric dosing: 50-75 mg/kg/day divided every 6 hours, with monitoring of serum concentrations recommended. For ophthalmic use: apply 1-2 drops to affected eye(s) every 3-6 hours depending on severity. Oral administration should be on an empty stomach (1 hour before or 2 hours after meals) for optimal absorption. Treatment duration typically ranges from 7-14 days depending on infection type and clinical response. Serum concentration monitoring is advised during prolonged therapy (>2 weeks) or in patients with hepatic impairment.

Precautions

Chloromycetin carries a boxed warning for serious and potentially fatal blood dyscrasias including aplastic anemia, which may occur during or weeks after treatment completion. Complete blood counts should be performed before therapy, every 2 days during therapy, and for at least 2 weeks after discontinuation. Use with extreme caution in patients with hepatic or renal impairment, requiring dosage adjustment and therapeutic drug monitoring. Avoid unnecessary use; reserve for serious infections where benefits outweigh risks. Monitor for superinfection or fungal overgrowth. Use during pregnancy only if clearly needed (Category C); crosses placenta and may cause “gray baby syndrome” in neonates. Excreted in breast milk; consider discontinuing nursing during treatment. May cause visual disturbances; caution when operating machinery.

Contraindications

Hypersensitivity to chloramphenicol or any component of the formulation. History of chloramphenicol-induced blood dyscrasias. Avoid use for trivial infections, prophylaxis, or in patients with known bone marrow suppression. Contraindicated in neonates, especially premature infants, due to risk of “gray baby syndrome” (cardiovascular collapse). Not recommended for treatment of minor bacterial or viral infections. Avoid concurrent use with other drugs that suppress bone marrow function. Contraindicated in patients with acute intermittent porphyria.

Possible side effects

Serious: Bone marrow suppression (dose-related reversible anemia, thrombocytopenia, leukopenia; idiosyncratic irreversible aplastic anemia), gray baby syndrome in neonates (abdominal distension, cyanosis, vasomotor collapse), hypersensitivity reactions (fever, rash, angioedema), optic and peripheral neuritis (especially with prolonged use).

Common: Gastrointestinal disturbances (nausea, vomiting, diarrhea), headache, mild depression, mucosal candidiasis. Ophthalmic use may cause transient burning, stinging, or blurred vision.

Rare: Hemolytic anemia in patients with glucose-6-phosphate dehydrogenase deficiency, Jarisch-Herxheimer reaction during treatment of spirochetal infections, toxic epidermal necrolysis.

Drug interaction

Chloromycetin inhibits hepatic microsomal enzymes, potentially increasing serum concentrations of: phenytoin, tolbutamide, chlorpropamide, warfarin (enhanced anticoagulant effect), and cyclophosphamide. Concurrent use with other bone marrow suppressants (cytotoxic drugs, radiation therapy) increases risk of hematologic toxicity. Barbiturates may decrease chloramphenicol concentrations. May antagonize bactericidal activity of penicillins and aminoglycosides in vitro. Concurrent ethanol use may cause disulfiram-like reaction. Live bacterial vaccines may have reduced efficacy during treatment.

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 a missed one. Maintain regular dosing intervals to ensure consistent therapeutic levels. If multiple doses are missed, contact healthcare provider for guidance on resuming therapy. For ophthalmic preparations, apply missed dose when remembered unless next dose is due shortly.

Overdose

Symptoms of overdose include nausea, vomiting, altered mental status, gray baby syndrome in infants (pallor, abdominal distension, cyanosis, cardiovascular collapse). Treatment is primarily supportive: gastric lavage if recent ingestion, activated charcoal may be beneficial. Hemodialysis is ineffective due to high protein binding but charcoal hemoperfusion may be considered in severe cases. Monitor complete blood counts frequently for several weeks. There is no specific antidote; manage complications symptomatically. In cases of cardiovascular collapse, aggressive fluid resuscitation and vasopressor support may be required.

Storage

Store at controlled room temperature (15-30°C or 59-86°F) in tight, light-resistant containers. Protect from moisture and excessive heat. Do not freeze. Keep oral and ophthalmic formulations in their original containers. Discard any unused portion of oral suspension after 14 days. Do not use if discoloration or precipitation occurs. Keep out of reach of children and pets. Do not transfer to unlabeled containers.

Disclaimer

This information is for educational purposes only and does not constitute medical advice. Chloromycetin is a potent antibiotic with serious potential adverse effects and must be used only under direct supervision of a qualified healthcare professional familiar with its risks and benefits. The prescriber should carefully consider the indication, alternative treatments, and monitoring requirements before initiation. Patients should not self-medicate with this drug. Always follow the prescribed dosage and report any adverse effects immediately. This summary does not include all possible information about this medication; consult the full prescribing information and current clinical guidelines for comprehensive guidance.

Reviews

“Chloromycetin remains our go-to antibiotic for multidrug-resistant typhoid cases in this region. While we monitor patients meticulously for hematologic effects, its efficacy in serious cases where other antibiotics fail is unquestionable.” - Infectious Disease Specialist, Southeast Asia

“Used chloramphenicol eye drops for a confirmed Pseudomonas corneal ulcer after multiple other antibiotics failed. Complete resolution within 10 days with appropriate dosing. Remarkable efficacy but requires careful patient education about potential systemic absorption.” - Ophthalmologist, Teaching Hospital

“Despite its toxicity concerns, chloramphenicol saved a patient with community-acquired meningitis resistant to third-generation cephalosporins. We used therapeutic drug monitoring and daily CBCs throughout the 14-day course with successful outcome and no adverse effects.” - Intensive Care Specialist, University Hospital

“While we reserve it for absolute necessities, chloramphenicol’s spectrum and CNS penetration make it invaluable in certain neurosurgical infections. The key is strict adherence to monitoring protocols and having informed consent discussions about the risk-benefit ratio.” - Neurosurgeon, Tertiary Care Center