Effect of sodium sulfadimethylpyrimidine on mixed function oxidase in chicken

Objective: Study of in vivo and in vitro effect of sodium sulfadimethylpyrimidine (SDMP) on mixed function oxidase system in chicken. Methods: Effect of SDMP on mixed function oxidase was studied using different dosages, durations, sex and strains of chicken. Microsomes were isolated by calcium precipitation. The levels of CYP 450 and b5 were determined using the extinction coefficient of 91, 85 mM - 1 cm - 1 respectively. Activities of drug metabolizing enzymes were assayed. Results: SDMP treatment at 100 mg/kg resulted In an increase in the activities of chickens' mixed function oxidase system. Hubbard and Vancob strains showed significant inhibition of mixed function oxidase system at 300 mg/kg, however, RRI strain showed significant increase. SDMP exhibited uncompetitive type of inhibition (Ki = 4.2 mM) of aminopyrine N-demethylase. Inhibition of aminopyrine N-demethylase was confirmed using reconstituted system containing affinity purified CYP 450, CYP 450 - reductase and L-α- lecithin. Conclusion: Our studies suggest that SDMP influences mixed function oxidase in chicken and it depends on the dose, duration of SDMP and strain of chicken used.