Pharmacokinetics of nine sulphonamides in goats

Pharmacokinetics of nine sulphonamides was investigated in healthy goats. From the plasma disappearance curves after intravenous bolus injection clearance rates, plasma half‐lives and distribution volumes were calculated. Plasma‐protein binding was measured in vitro and in vivo. The highest‐bound sulphonamides showed the highest concentration dependence of protein binding. Plasma disappearance curves were in accordance with the one‐, two‐ or three‐compartment pharmacokinetic models. Disposition of sulphadimidine after 100 or 200 mg/kg and of sulphisomidine after 200 mg/kg showed limited enzyme capacity characteristics. Disposition of sulphadimidine, sulphisomidine and sulphadimethoxine was dose‐dependent. Goats could also be divided in fast and slow sulphadimidine eliminators. Correlation was found only between clearance and half‐life. Dosage regimens were calculated for seven sulphonamides.