Understanding Chloramphenicol and Its Primary Use
Chloramphenicol is a broad-spectrum antibiotic that has been in use for many decades after its discovery in 1947 [1.2.5]. While it exists in various forms, including intravenous (IV) and oral capsules for serious systemic infections like meningitis and typhoid fever, its most common modern application in many regions is as a topical preparation for the eyes [1.2.5, 1.2.3]. Chloramphenicol eye ointment and eye drops are primarily prescribed to treat surface ocular infections caused by bacteria [1.2.6].
The most frequent condition treated with this ointment is acute bacterial conjunctivitis, often called "pink eye" [1.6.7]. Symptoms of this condition include redness in the white of the eye, a gritty or irritated feeling, and often a sticky yellow or green discharge that can make the eyelids stick together, especially upon waking [1.6.7, 1.4.2]. Chloramphenicol is effective against many of the common bacteria responsible for these infections, including Staphylococcus aureus, Streptococcus pneumoniae, and Haemophilus influenzae [1.2.6]. It is also sometimes used to treat styes, which are infections of the glands in the eyelid [1.2.8].
How Chloramphenicol Works (Pharmacology)
Chloramphenicol functions as a bacteriostatic agent, which means it stops bacteria from multiplying rather than killing them outright [1.3.8]. It achieves this by inhibiting protein synthesis within the bacterial cell [1.3.1]. Specifically, the drug binds to the 50S subunit of the bacterial ribosome, which is a crucial component of the machinery that builds proteins [1.3.3]. By interfering with the peptidyl transferase step, it prevents the formation of peptide bonds, halting the creation of essential proteins that bacteria need to grow and replicate [1.3.2, 1.3.3]. This action gives the body's immune system the upper hand to clear the infection. Due to its lipid-soluble nature, chloramphenicol can effectively penetrate the cornea to reach the site of infection [1.3.4].
Proper Application and Dosage
Proper application is key to the effectiveness of the treatment and to prevent contamination. Always wash hands before and after use [1.5.7].
- Preparation: If desired, warm the tube under running water to soften the ointment [1.5.1]. Remove the cap and avoid touching the tip to any surface, including the eye itself [1.5.2].
- Application: Gently pull the lower eyelid down to create a small pocket [1.5.7].
- Dosing: Squeeze a small ribbon of ointment (about 1 cm or a half-inch) into this pocket [1.5.2, 1.6.2].
- Distribution: Close the eye for a moment and blink a few times to help spread the ointment across the entire surface of the eye [1.5.2].
The typical adult and child (over 2 years) dosage is to apply the ointment every three hours or as directed by a physician [1.2.1, 1.6.2]. Treatment usually lasts for five days and should be continued for at least 48 hours after the eye appears normal to ensure the infection is fully resolved [1.4.8, 1.2.6]. Vision will likely be blurry for a short time after application [1.4.2].
Potential Side Effects and Important Warnings
While generally safe for topical use, there are potential side effects. The most common are localized and temporary, such as mild burning, stinging, or irritation upon application [1.4.3]. Blurred vision immediately after using the ointment is also expected [1.4.2].
More serious side effects are rare for the ophthalmic form but are well-documented for systemic use. The most significant concern historically associated with chloramphenicol is bone marrow suppression, which can, in very rare instances (estimated at less than one in 224,716 prescriptions for eye drops), lead to a fatal condition called aplastic anemia [1.4.1, 1.2.5]. Because of this remote risk, it should only be used for bacterial infections when less potentially hazardous drugs are not suitable [1.2.6]. Patients with a personal or family history of blood problems should not use this medication [1.4.2]. If symptoms like unusual tiredness, bruising, a persistent sore throat, or new infections appear, medical attention is required immediately [1.4.3].
Comparison of Topical Antibiotics for Bacterial Conjunctivitis
Chloramphenicol is one of several options for treating bacterial eye infections. Other commonly prescribed antibiotics have different spectrums of activity and profiles.
| Medication | Class | Common Form | Key Considerations |
|---|---|---|---|
| Chloramphenicol | Broad-Spectrum | Ointment, Drops | Effective against many bacteria, but not Pseudomonas aeruginosa [1.2.6]. Carries a very rare but serious risk of aplastic anemia [1.4.1]. |
| Erythromycin | Macrolide | Ointment | Often used as a first-line alternative; good for common bacterial infections [1.7.3, 1.7.5]. |
| Polymyxin B / Trimethoprim | Combination | Drops | Broad-spectrum combination effective against a wide range of bacteria, including Pseudomonas [1.7.2]. |
| Ofloxacin / Ciprofloxacin | Fluoroquinolone | Drops | Broad-spectrum with good efficacy, but often reserved to prevent resistance [1.7.5]. A study showed ofloxacin to have similar clinical improvement rates to chloramphenicol [1.7.7]. |
| Azithromycin | Macrolide | Drops | Can be effective with less frequent dosing [1.7.5]. |
Conclusion
In summary, chloramphenicol ointment is a time-tested antibiotic prescribed for superficial bacterial eye infections, most commonly bacterial conjunctivitis. It works by halting the synthesis of proteins necessary for bacterial growth. While it is effective and generally well-tolerated, with only minor side effects like temporary stinging, it carries a very rare but serious risk of aplastic anemia, which dictates that it should be used judiciously and exactly as prescribed. A typical course of treatment lasts about five days, and it is crucial to complete the entire course to prevent the infection's return [1.4.8]. Always consult a healthcare provider for diagnosis and treatment, as chloramphenicol is ineffective against viral or fungal eye infections [1.2.4].
Disclaimer: This article is for informational purposes only and does not constitute medical advice. Always consult with a qualified healthcare professional for any health concerns or before making any decisions related to your health or treatment.
Authoritative Link: Chloramphenicol (Ophthalmic Route) - Mayo Clinic
