Pharmacokinetics of ivermectin in cats receiving a single subcutaneous dose

Ivermectin is effective against ecto- and endoparasites. It is included in a plan of the Filariasis Division, Thailand for filariasis control and prevention by interrupting transmission of Brugia malayi-microfilariae from cat reservoirs to humans via mosquitoes. The pharmacokinetics of ivermectin in eight healthy cats receiving a single subcutaneous dose of 0.2 mg/kg was investigated. Jugular blood samples were collected periodically for up to 30 days after dosing. The serum ivermectin concentrations were measured by high performance liquid chromatography with fluorescence detection. The pharmacokinetic parameters (mean ± S.D.) derived from one-compartment model analysis were as follows: Tmax 1.22 ± 0.49 day, Cmax 16.75 ± 4.04 ng/mL, kab 2.62 ± 1.86 day−1, t1/2ab 0.27 ± 0.25 day, kel 0.27 ± 0.14 day−1, t1/2el 2.53 ± 2.24 day, Vd/F 9.81 ± 5.41 L/kg, Cl/F 2.21 ± 0.69 L/kg/day and AUC0→∞ 98.31 ± 30.52 ng day/mL. In conclusion, the pharmacokinetics of ivermectin in cats receiving a single dose of 0.2 mg/kg by subcutaneous injection revealed a rapid absorption, high distribution, slow elimination and high possibility for the elimination of B. malayi-microfilariae from currently endemic regions.