Pharmacology: Pharmacodynamics: COTRIMOXAZOLE (GLOBAXOL) contains two active ingredients, sulfamethoxazole and trimethoprim acting synergistically by blockage of two enzymes that catalyze successive stages in the biosynthesis of folinic acid in the microorganisms. This mechanism usually results in bactericidal activity in vitro at concentrations which the individual components are only bacteriostatic. COTRIMOXAZOLE (GLOBAXOL) is often effective against organisms that are resistant to one of the active ingredients.
The antibacterial effect of COTRIMOXAZOLE (GLOBAXOL) covers a wide range of Gram-positive and Gram-negative organisms e.g., Streptococci, Staphylococci, Pneumococci, Neisseria, Bordetella, Salmonella, Klebsiella/Aerobacter, Shigella and Vibrio cholerae.
A particularly high degree of enhanced activity is exhibited against the problem organisms, Haemophilus influenzae, E. coli and Proteus mirabilis or vulgaris.
Pharmacokinetics: COTRIMOXAZOLE (GLOBAXOL) when given orally, plasma concentrations of trimethoprim and sulfamethoxazole are generally around the optimal ratio of 1:20, although they may vary from 1:2 to 1:30 or more. The ratio of the two drugs is usually much lower in the tissues (often around 1:2 to 1:5) since trimethoprim, the more lipophilic drug, penetrates many tissues better than sulfamethoxazole and has a much larger volume of distribution. In urine the ratio may vary from 1:1 to 1:5 depending on the pH.