Chloramphenicol is a bacteriostatic antibiotic with a broad spectrum of activity against both Gram-positive and Gram-negative bacteria, as well as certain other microorganisms. It functions by inhibiting bacterial protein synthesis through binding to the 50S ribosomal subunit, making it a critical agent in managing serious infections where other antibiotics may be ineffective or contraindicated. Its use is typically reserved for situations where the benefits outweigh potential risks due to associated adverse effects. Proper administration under medical supervision is essential to maximize therapeutic outcomes while minimizing hazards.

Features

• Chemical structure: C₁₁H₁₂Cl₂N₂O₅
• Mechanism: Inhibits bacterial protein synthesis by binding to the 50S ribosomal subunit
• Spectrum: Broad activity against aerobic and anaerobic Gram-positive and Gram-negative bacteria, Rickettsia, and Chlamydia
• Formulations: Available as oral capsules, eye drops/ointments, and intravenous preparations
• Bioavailability: Well-absorbed orally with approximately 75–90% bioavailability
• Half-life: Approximately 1.5–3.5 hours in adults with normal hepatic and renal function
• Metabolism: Primarily hepatic via glucuronidation
• Excretion: Mainly renal (5–15% unchanged) and biliary

Benefits

• Effective against multidrug-resistant organisms, including Salmonella typhi and Haemophilus influenzae
• Rapid tissue penetration, achieving therapeutic concentrations in cerebrospinal fluid, making it valuable in treating bacterial meningitis
• Cost-effective alternative in resource-limited settings for serious infections
• Available in multiple formulations allowing flexible administration routes based on clinical need
• Demonstrates efficacy in ocular infections with minimal systemic absorption when used topically

Common use

Chloramphenicol is indicated for serious infections caused by susceptible organisms when less potentially dangerous agents are ineffective or contraindicated. Key applications include bacterial meningitis caused by H. influenzae, Neisseria meningitidis, or Streptococcus pneumoniae; typhoid fever caused by Salmonella typhi; rickettsial diseases such as Rocky Mountain spotted fever; and anaerobic infections including brain abscesses and intra-abdominal infections. Ophthalmologically, it is used for superficial eye infections involving susceptible bacteria. Its use is generally restricted due to the risk of bone marrow suppression, necessitating careful patient selection and monitoring.

Dosage and direction

Dosage must be individualized based on infection severity, pathogen susceptibility, and patient factors including hepatic and renal function. For serious systemic infections in adults, the typical oral or intravenous dose is 50 mg/kg/day divided every 6 hours, not exceeding 4 g daily. In pediatric patients, the dose is 50–75 mg/kg/day divided every 6 hours. For meningeal infections, higher doses of 75–100 mg/kg/day may be required. Ophthalmic preparations are typically applied as 1–2 drops or a small amount of ointment to the affected eye every 3–6 hours. Treatment duration should be the shortest effective period, generally not exceeding two weeks for systemic therapy to reduce toxicity risk. Complete the full prescribed course even if symptoms improve earlier.

Precautions

Use chloramphenicol with extreme caution due to potential serious adverse effects. Monitor complete blood counts before therapy, every 2 days during therapy, and for several days after discontinuation to detect early signs of bone marrow suppression. Avoid concurrent use with other myelosuppressive drugs. Use cautiously in patients with hepatic or renal impairment, as reduced clearance may increase toxicity risk. Pregnancy Category C: use only if potential benefit justifies potential fetal risk. Exercise caution in breastfeeding women as chloramphenicol is excreted in breast milk and may cause gray baby syndrome. Genetic testing for G6PD deficiency is recommended in susceptible populations to avoid hemolytic anemia.

Contraindications

Chloramphenicol is contraindicated in patients with known hypersensitivity to chloramphenicol or any component of the formulation. Avoid use in individuals with a history of chloramphenicol-induced blood dyscrasias. Do not use for trivial infections, prophylaxis, or when less dangerous agents would be effective. Contraindicated in neonates, especially premature infants, due to risk of gray baby syndrome characterized by cardiovascular collapse. Avoid concomitant use with drugs that strongly inhibit hepatic enzymes or compete for glucuronidation pathways. Not recommended for patients with pre-existing bone marrow suppression or hematologic diseases.

Possible side effect

• Hematologic: Bone marrow suppression (dose-related and reversible), aplastic anemia (idiosyncratic and often fatal), leukopenia, thrombocytopenia, granulocytopenia
• Gastrointestinal: Nausea, vomiting, diarrhea, glossitis, stomatitis
• Neurologic: Optic neuritis, peripheral neuropathy, headache, confusion, delirium
• Hypersensitivity: Rash, fever, angioedema, anaphylaxis (rare)
• Gray baby syndrome: Abdominal distension, cyanosis, vasomotor collapse, death in neonates
• Other: Superinfections, including fungal overgrowth; Jarisch-Herxheimer reaction in spirochetal infections

Drug interaction

• Oral anticoagulants (warfarin): Increased anticoagulant effect due to inhibition of vitamin K-dependent clotting factor synthesis
• Phenytoin, phenobarbital: Increased serum levels of these anticonvulsants due to inhibited metabolism
• Sulfonylureas: Enhanced hypoglycemic effect
• Iron preparations, vitamin B12: May antagonize hematopoietic response
• Other myelosuppressive agents (e.g., chemotherapy drugs): Additive bone marrow toxicity
• Drugs metabolized by hepatic cytochrome P450 system: Potential for increased serum concentrations
• Penicillins: Possible antagonism of bactericidal activity in certain infections

Missed dose

If a dose is missed, administer it as soon as remembered unless it is almost time for the next scheduled dose. In that case, skip the missed dose and resume the regular dosing schedule. Do not double the dose to make up for a missed one. Maintaining consistent serum levels is important for efficacy, but occasional missed doses are unlikely to significantly impact treatment outcomes if the overall regimen is adhered to. For ophthalmic preparations, apply the missed dose when remembered unless close to the next application time.

Overdose

Acute overdose may manifest as nausea, vomiting, and altered mental status. The most serious consequence is bone marrow suppression, which may be irreversible in cases of aplastic anemia. Gray baby syndrome may occur in infants with doses exceeding 25 mg/kg/day. There is no specific antidote. Management includes immediate discontinuation, supportive care, and monitoring of hematologic parameters. Gastric lavage may be considered if ingestion was recent. Hemodialysis is not effective due to high protein binding, but exchange transfusion has been used in neonates. Chronic overdose leads to cumulative bone marrow toxicity requiring prolonged monitoring.

Storage

Store at controlled room temperature (20–25°C or 68–77°F). Protect from light and moisture. Keep oral and intravenous formulations in tightly closed containers. Do not freeze. Keep out of reach of children. Discard any unused portion after the completion of therapy or after the expiration date. For ophthalmic preparations, avoid contaminating the tip of the dropper or tube. Do not use if the solution appears discolored or contains particles. Follow specific storage instructions provided with the particular formulation.

Disclaimer

This information is for educational purposes only and does not constitute medical advice. Chloramphenicol is a potent antibiotic with serious potential adverse effects and should only be used under direct supervision of a qualified healthcare professional. The prescriber must carefully weigh benefits against risks for each individual patient. Always follow the specific instructions provided by your healthcare provider and the product labeling. Do not self-medicate or share this medication with others. Report any adverse effects to your healthcare provider immediately.

Reviews

“Chloramphenicol remains a vital agent in our antimicrobial arsenal for multidrug-resistant Salmonella infections. While we exercise extreme caution with monitoring, its efficacy in critical cases is unmatched.” – Infectious Disease Specialist, 15 years experience

“As an ophthalmologist, I find chloramphenicol ointment exceptionally effective for bacterial conjunctivitis. The topical formulation provides excellent coverage with minimal systemic absorption when used appropriately.” – Ophthalmologist, 8 years experience

“In resource-limited settings, chloramphenicol has been invaluable for managing meningitis outbreaks. However, the requirement for frequent blood monitoring presents significant practical challenges.” – Tropical Medicine Physician, 12 years experience

“The risk of irreversible aplastic anemia, though rare, necessitates that this drug be reserved for only the most serious infections where no alternatives exist. Our protocol includes detailed informed consent.” – Hematologist, 20 years experience