Pharmacokinetics of furosemide in goats following intravenous, intramuscular, and subcutaneous administrations

Furosemide, a loop diuretic drug, is recommended for use in cases of edema, ascites, congestive heart failure, toxicosis, and acute renal failure in goats. However, its pharmacokinetics and bioavailability have not been reported yet in this species. The aim of this study was to determine the pharmacokinetics and bioavailability of furosemide in goats following intravenous (IV), intramuscular (IM), and subcutaneous (SC) administrations at a dose of 2.5 mg/kg. Six clinically healthy goats received furosemide by each route in a three-way crossover pharmacokinetic design with a 15-day washout period between administrations. The plasma concentrations of furosemide were determined using the high-performance liquid chromatography-UV method and analyzed by non-compartmental analysis. The elimination half-life following IV, IM, and SC administration was 0.71 (0.67–0.76) h, 0.69 (0.61–0.74) h, and 0.70 (0.67–0.79) h, respectively. The volume of distribution at steady state and total clearance for the IV route were 0.17 (0.16–0.19) L/kg and 0.30 (0.27–0.33) L/h/kg, respectively. The peak plasma concentrations of furosemide following IM and SC administrations were 11.19 (10.33–11.95) and 6.49 (5.92–7.00) μg/ml at 0.23 (0.16–0.25) and 0.39 (0.33–0.42) h, respectively. The bioavailability was 109.84 (104.92–116.99)% and 70.80 (55.77–86.67)% for the IM and SC routes, respectively. The pharmacokinetics of furosemide following the IV, IM, and SC administrations in goats demonstrated significant differences, which may have clinical and toxicological implications requiring further investigations.