Metabolism and Pharmacokinetics of Sulfamonomethoxine in Edible Fish Species

Abstract

Sulfamonomethoxine has been efficacious in the treatment of various bacterial diseases of fish. The present paper reviews recent studies on the metabolism and pharmacokinetics of sulfamonomethoxine in edible fish species such as yellowtail, rainbow trout, and eel. N4-Acetylated metabolites were the major metabolites whereas glucuronic acid conjugates were the minor metabolites. Moreover, a double conjugated metabolite, the glucuronic acid conjugate of N4-acetylsulfamonomethoxine was found in three species. Serum concentrations after intravascular administration could be fitted to be a two-compartment model and those after oral administration to a one-compartment model in all three species. The absorption parameters of sulfamonomethoxine in eel were substantially different from those in rainbow trout and yellowtail. In eel, the drug was assimilated slowly and cleared very slowly. On the other hand, in yellowtail, sulfamonomethoxine was well distributed to the tissues and was cleared quickly. As an application of the pharmacokinetic studies, the Japanese dosage regimens of sulfa-monomethoxine in three fish species were evaluated.