A fixed-dose combination topical ophthalmic preparation containing three distinct antibacterial agents. Sulphacetamide is a sulfonamide antibiotic, Neomycin is an aminoglycoside, and Bacitracin is a polypeptide antibiotic. This combination provides broad-spectrum coverage against common Gram-positive and Gram-negative bacteria, including some strains resistant to single agents. It is primarily used for the prophylaxis and treatment of superficial bacterial infections of the eye and its adnexa. The combination is synergistic against many organisms and helps prevent the emergence of resistance.
Adult: Instill 1-2 drops into the affected eye(s) every 4 to 6 hours. In severe infections, may be used every 2-3 hours initially, as directed by the physician. A small amount (approx. 1 cm ribbon) of ointment can be applied in the lower conjunctival sac 2-4 times daily or at bedtime as an adjunct to drops.
Note: 1. Wash hands before use. 2. Tilt head back, pull lower eyelid down to form a pouch. 3. Instill drops/apply ointment without touching the tip to the eye, eyelids, or any surface. 4. Close eyes gently for 1-2 minutes. Apply gentle pressure to the inner corner of the eye (nasolacrimal duct) for about a minute to minimize systemic absorption. 5. If using multiple eye medications, wait at least 5-10 minutes between applications. Ointments should be applied last. 6. Do not wear contact lenses during treatment.
The combination exerts a bactericidal effect through three distinct mechanisms, providing synergistic action and a broad antibacterial spectrum. Sulphacetamide competitively antagonizes para-aminobenzoic acid (PABA), inhibiting bacterial dihydropteroate synthase, a key enzyme in folic acid synthesis. Neomycin binds to the 30S ribosomal subunit, causing misreading of mRNA and inhibiting bacterial protein synthesis. Bacitracin interferes with bacterial cell wall synthesis by inhibiting the dephosphorylation of the lipid carrier (undecaprenyl pyrophosphate) that transports peptidoglycan precursors across the cytoplasmic membrane.
Pregnancy: Category C (US FDA). There are no adequate and well-controlled studies in pregnant women. Sulphonamides cross the placenta. Use only if the potential benefit justifies the potential risk to the fetus, especially near term (risk of kernicterus).
Driving: May cause temporary blurred vision after instillation, especially the ointment. Patients should not drive or operate machinery until vision clears.
| Silver preparations (e.g., Silver Nitrate) | Incompatible; may form insoluble salts with Sulphacetamide. | Major |
| Other Aminoglycosides (e.g., Gentamicin, Tobramycin) given systemically or topically | Additive risk of ototoxicity and nephrotoxicity. | Moderate |
| Neuromuscular blocking agents (e.g., Succinylcholine, Tubocurarine) | Neomycin may potentiate neuromuscular blockade, leading to respiratory depression. | Major |
| Oral Anticoagulants (e.g., Warfarin) | Sulfonamides may displace warfarin from protein binding sites, potentiating its effect. Risk is low with topical use. | Moderate |
| Methotrexate | Sulfonamides may displace methotrexate, increasing its toxicity. Risk is low with topical use. | Moderate |
Same composition (Sulphacetamide (60mg) + Neomycin (5mg) + Bacitracin (250IU)), different brands: