Pharmacokinetics and residual elimination pattern of enrofloxacin and its metabolite ciprofloxacin in Babylonia areolate

In recent years, frequent occurrence of enrofloxacin residues in breeding snail (Babylonia areolate) has been a problem. To reveal the pharmacokinetic characteristics of enrofloxacin and its metabolites in B. areolate, and to design a rational dosing method and the rest period, we fed B. areolate with 20 mg·kg⁻¹ of enrofloxacin mixture at water temperature of (24.5 ± 2.5) ° C, and then sampled at 0.17^th, 0.25^th, 0.5^th, 1^st, 2^nd, 4^th, 12^th, 24^th, 48^th, 72^nd, 120^th, 168^th, 240^th and 360^th hour after the dosing. Shimadzu 8050 LC-MS/MS was used to determine the drug concentration in the tissues in each period. The results show that the drug-time data applied to the non-atrial models in Gastropod muscle, proboscis (Including esophageal glands) and liver: the C_max of enrofloxacin was 7.82, 10.5 and 31.47 mg·kg⁻¹, respectively; the C_max of ciprofloxacin (Metabolite) was 0.72, 0.89 and 1.21 mg·kg⁻¹, respectively; the enrofloxacin t_max was 1, 4 and 4 h, respectively; the ciprofloxacin t_max was 4, 12 and 4 h, respectively; the enrofloxacin t_1/2z was 38.22, 52.44 and 62.40 h, respectively; the ciprofloxacin t_1/2z was 66.23, 33.11 and 27.06 h, respectively; the theoretical drug rest period was 16.94, 16.79 and 17.99 d, respectively. The results indicate that for all tissues, 20 mg·kg⁻¹ of enrofloxacin mixture with the C_max/MIC over 10 is suitable for the treatment of B. areolate disease caused by Vibrio harveyi (MIC, 0.45 mg·L⁻¹). It is recommended that the drug rest period should not be less than 440.76 ℃·d and the dosing should be once every 2 d, a total of 3 times.