The Pharmacokinetics of Rafoxanide following Single Dose Intravenous and Oral Administration in Goats

The study was conducted to determine the plasma concentrations and pharmacokinetic parameters of rafoxanide after a single intravenous (10 mg/kg) and oral (22.5 mg/kg) administrations in black Bengal female goats. Maximum (87.63 11.71 mg/mL) and minimum (1.8 0.24 mg/mL) plasma concentrations of rafoxanide were recorded at 0.08 and 12 h respectively after i.v. administration. The elimination half life (t1/2b), total body clearance (ClB) and volume of distribution (Vdarea) values were 2.89 0.26 h, 0.05 0.002 L/kg/h and 0.19 0.02 L/kg respectively. An adequate plasma level of rafoxanide (14.63 2.12 mg/mL) was detected at 1h followed by gradual increase and peak concentration level (30.88 4.30 mg/mL) was recorded at 36 h after oral administration. The rate of absorption (Ka), elimination half life (t1/2 b), total body clearance (ClB) and volume of distribution (Vdarea) values were 0.07 0.009 h-1, 138.02 13.99 h, 0.003 0.0003 L/kg/h, and 0.57 0.06 L/kg respectively. Plasma protein binding percentages of rafoxanide varied from 81.06 to 92.28 and its association and dissociation constants were 1.26 107 0.18 107 L/mol and 0.83 10-7 0.12 10-7 mol/L respectively. On conclusion, rafoxanide is slowly absorbed from the gastrointestinal tract, slowly eliminated; highly protein bound and persists for long time in blood of goat.