RESIDUE STUDY OF MEBENDAZOLE AND ITS METABOLITES HYDROXY-MEBENDAZOLE AND AMINO-MEBENDAZOLE IN EEL (ANGUILLA-ANGUILLA) AFTER BATH TREATMENT

Mebendazole (MBZ) is extensively used in eel culture for treatment of Pseudodactylogyrus spp. infections. This use may lead to residues of M BZ in eel tissues. Consequently, the residue profile of MBZ in eel aft er treatment with the drug is of special concern. Therefore, a residue study was performed in European eels (Anguilla anguilla), bath-treate d with MBZ at a dose of 1 mg/liter for 24 hr and kept at a water tempe rature of 25 degrees C. Liver, kidney, fat, skin, and muscle tissue sa mples were collected at intervals during and after treatment and analy zed for MBZ and its metabolites, hydroxy-MBZ (MBZ-OH) and amino-MBZ (M BZ-NH2), by HPLC. Results showed that MBZ is extensively metabolized t o MBZ-OH and MBZ-NH2. Liver and kidney were found to contain the highe st levels of MBZ metabolites, and fat contained the highest levels of the parent compound. Skin contained higher residue levels fdr all thre e compounds, compared with muscle tissue. MBZ and its hydroxy metaboli te were eliminated within 5 days from the edible parts (muscle and ski n) of the eels, whereas MBZ-NH2 could be detected by the 14th day afte r the end of the treatment period. Consequently, although MBZ and MBZ- OH constitute the residues of toxicological concern, MBZ-NH2 should be taken as the compound of interest for estimating the withdrawal time for consumption of eel treated with MBZ.