DBL Sulfamethoxazole & Trimethoprim Description

DBL Sulfamethoxazole 400 mg and Trimethoprim 80 mg Concentrate Injection BP is an antibacterial combination product, containing 16 mg Trimethoprim BP and 80 mg Sulfamethoxazole BP per mL in a 40 percent propylene glycol vehicle.
Sulfamethoxazole is a white or almost white, odourless crystalline powder. It is practically insoluble in water, sparingly soluble in ethanol (96%), freely soluble in acetone, slightly soluble in chloroform and in ether. It dissolves in dilute solutions of sodium hydroxide. Melting point is 167°C. Trimethoprim is a white or yellowish-white powder, odourless or almost odourless. It is very slightly soluble in water, slightly soluble in ethanol (96%), sparingly soluble in chloroform, practically insoluble in ether. Melting point is 199-203°C.
Excipients with known effect: Sodium; metabisulfite; Alcohol.
The solution is clear and has a pH of approximately 10. Hydrochloric acid and sodium hydroxide are used to adjust the pH during the manufacture of DBL Sulfamethoxazole 400 mg and Trimethoprim 80 mg Concentrate Injection BP.
Sulfamethoxazole: Chemical name: 3-(4-aminobenzenesulfonamido)-5-methylisoxazole.
Molecular formula: C₁₀H₁₁N₃O₃S.
Molecular weight: 253.28.
Trimethoprim: Chemical name: 2, 4-diamino-5-(3, 4, 5-trimethoxybenzyl) pyrimidine.
Molecular formula: C₁₄H₁₈N₄O₃.
Molecular weight: 290.3.
Excipients/Inactive Ingredients: Diethanolamine, Propylene glycol, Absolute alcohol, Sodium metabisulfite, Sodium hydroxide, Water for injections.