Sulphacetamide (12.5% w/v) + Chlorpheniramine Maleate (0.01% w/v) (Medical Monograph)

Overview

A sterile ophthalmic solution combining a bacteriostatic sulfonamide antibiotic (Sulphacetamide Sodium) with a first-generation alkylamine antihistamine (Chlorpheniramine Maleate). It is primarily indicated for the treatment of acute bacterial conjunctivitis and associated allergic symptoms like itching and redness. The combination provides a dual mechanism of action: antibacterial and anti-inflammatory/anti-pruritic.

Sulphacetamide is a competitive antagonist of para-aminobenzoic acid (PABA), inhibiting bacterial dihydropteroate synthase in the folic acid synthesis pathway, leading to bacteriostatic action. Chlorpheniramine is a reversible competitive antagonist at histamine H1 receptors, blocking the effects of histamine released during allergic reactions (vasodilation, increased capillary permeability, itching).