A sterile, topical ophthalmic solution combining two bactericidal antibiotics with complementary mechanisms of action. Polymyxin B is a cationic polypeptide antibiotic effective against Gram-negative bacteria, particularly Pseudomonas aeruginosa. Chloramphenicol is a broad-spectrum bacteriostatic antibiotic effective against a wide range of Gram-positive and Gram-negative bacteria, including Haemophilus influenzae and Streptococcus pneumoniae. This combination provides synergistic coverage for superficial ocular infections, particularly in the Indian context where bacterial conjunctivitis is common and often polymicrobial.
Adult: One to two drops in the affected eye(s) every 4 to 6 hours. In severe infections, may be used hourly initially, tapering as infection improves.
Note: 1. Wash hands. 2. Tilt head back. 3. Gently pull lower eyelid to form a pouch. 4. Instill prescribed drops without touching the dropper tip to eye or any surface. 5. Close eyes gently for 1-2 minutes. 6. Apply gentle pressure to the nasolacrimal duct (inner corner of eye) for 1 minute to minimize systemic absorption. 7. Wait at least 5-10 minutes before instilling any other eye medication.
The combination exerts a dual bactericidal/bacteriostatic action. Polymyxin B binds to the lipopolysaccharide (LPS) and phospholipids in the outer cell membrane of Gram-negative bacteria, acting as a cationic detergent that disrupts membrane integrity, leading to leakage of intracellular contents and cell death. Chloramphenicol inhibits bacterial protein synthesis by binding reversibly to the 50S subunit of the bacterial ribosome, preventing peptide bond formation. This combination is effective against a broad spectrum of ocular pathogens.
Pregnancy: Category C (US FDA). Chloramphenicol crosses the placenta. 'Gray Baby Syndrome' is a risk in the third trimester and near term. Use only if potential benefit justifies potential fetal risk. Topical use is generally considered low risk, but should be avoided in late pregnancy.
Driving: May cause temporary blurred vision after instillation. Patients should not drive or operate machinery until vision clears.
| Other Myelosuppressive drugs (e.g., Chemotherapy, Azathioprine) | Increased risk of bone marrow toxicity. | Major |
| Vitamin B12, Folic Acid, Iron supplements | Chloramphenicol may antagonize the hematinic response. | Moderate |
| Penicillins, Cephalosporins | Chloramphenicol, being bacteriostatic, may antagonize the bactericidal action of these drugs in systemic infections. Relevance topical is low. | Moderate |
| Paracetamol (Acetaminophen) | Increased risk of Chloramphenicol toxicity (prolonged half-life) with systemic use. | Moderate |
| Warfarin | Chloramphenicol may inhibit metabolism, increasing anticoagulant effect. | Major |
| Phenytoin, Phenobarbital | Altered metabolism of Chloramphenicol. | Moderate |
Same composition (Polymyxin B (5000IU/ml) + Chloramphenicol (4mg/ml)), different brands: