Determination of sulfamonomethoxine in tilapia (Oreochromis niloticus × Oreochromis mossambicus) by liquid chromatography-tandem mass spectrometry and its application pharmacokinetics study.

A precise and reliable analytical method to measure trace levels of sulfamonomethoxine (SMM) and N-acetyl metabolite in tilapia samples using liquid chromatography-tandem mass spectrometry was developed. Optimized chromatographic separation was performed on C18 reversed-phase columns using gradient elution with methanol and 5 mmol/L of an ammonium acetate aqueous solution (adjusted to pH 3.5 using formic acid). This study investigated the pharmacokinetic properties and tissue distribution of SMM and its major metabolite N-acetyl sulfamonomethoxine (AC-SMM) in tilapia after a single dose of 100 mg kg body weight of orally administered SMM. Blood and tissues were collected between 0.5 and 192 h with 14 total sampling time points. SMM was rapidly absorbed, and extensively distributed in the bile and liver through systemic circulation. Enterohepatic circulation of SMM was observed in the tilapia body. Acetylation percentages were 45% (blood), 90% (liver), 62% (kidney), 98% (bile), and 52% (muscle). High concentrations of AC-SMM accumulated in the tilapia bile. At 192 h, AC-SMM concentration in the bile remained at 4710 μg kg. The k value of AC-SMM (0.015 h) in the blood was lower than that of SMM (0.032 h). This study demonstrated effective residue monitoring and determined the pharmacokinetic properties of SMM and AC-SMM in tilapia.