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What is Ratio of sulfamethoxazole and trimethoprim in cotrimoxazole tablet is:- and explain in detail?
COTRIMOXAZOLE This is a fixed dose combination of sulfamethoxazole and trimethoprim in a ratio of 5:1. Due to different bioavailability (more for sulfamethoxazole), plasma concentration of the two drugs attained is 20:1 (in vivo), which is the best bactericidal concentration required. The bactericidal activity is due to sequential blockade at two steps in the DNA synthesis (sulfamethoxazole inhibits folate synthase and trimethoprim inhibits DHFRase). It is the drug of choice for pneumocystosis, nocardiosis and infections caused by Burkholderia cepacia.