Comparative pharmacokinetics of doxycycline in crayfish (Procambarus clarkii) following oral, intramuscular, and intrasinus administrations.

The objective of the present study was to investigate the pharmacokinetic (PK) properties of doxycycline (DC) in crayfish after three different drug administrations of oral (per os , P.O.) gavage, intramuscular (IM) injection, and intrasinus (IS) injection at a dose of 20 mg/kg at 24.0 °C. Samples of hepatopancreas, muscle, gill, and hemolymph were collected at pre-determined time points after cessation of drug treatment (n = 5 for per time point). DC concentrations were determined by high-performance liquid chromatography with an ultraviolet detector. Results demonstrated that the multiple-peak phenomenon occurred in hemolymph and tissues irrespective of using any drug administration. With the changing of drug administration, the PK parameters were correspondingly altered. The elimination rate constant (t 1/2λ) were 28.90, 32.99, and 31.70 h; 42.00, 60.21, and 25.28 h; 32.17, 26.00, and 21.15 h; 69.53, 23.25, and 31.20 h in hepatopancreas, muscle, gill, and hemolymph after P.O., IM, and IS dosing, respectively. The values of the area under the concentration-time curve (AUC last) after IM and IS treatment were comparable in hepatopancreas, muscle, gill, and hemolymph, respectively, but the value following P.O. treatment was less than the values after IM and IS treatment except for hepatopancreas that presented an opposite trend. The volume of distribution (V z _F) was estimated to be 2625.30 mL/kg, and the systemic total body (Cl_F) was 58.30 mL/h/kg. Finally, the P.O. and IM bioavailability were calculated to be 19.58% and 104.76%. This study will provide the useful PK information of DC after different administrations, and is beneficial for a specific dosage regime in line with the drug given route. • Doxycycline's PKs were investigated in crayfish after P.O., IM, and IS administrations. • The changing of drug administration considerably affected t 1/2λz , T max , C max , and AUC last. • Bioavailability values were 19.58% and 104.76% after oral and intramuscular dosing. • The results provide useful information for the effective use of doxycycline in crayfish. [ABSTRACT FROM AUTHOR]