Pharmacokinetics of Orally Administered Clonidine in Dogs.

Clonidine is an α-2 agonist shown to be both well tolerated and useful in the treatment of canine fear-based disorders, although it is perceived to have a short duration of action. Clonidine is available in regular release and extended-release formulations, but canine pharmacokinetic (PK) and pharmacodynamic (PD) data on any clonidine formulation are lacking. The aim of this study was to establish PK and PD parameters of regular release (RR) clonidine in dogs. Clonidine RR (n = 6) was orally administered at 0.05 mg/kg to laboratory beagles. Clonidine RR showed a maximum concentration (Cmax) 1.5-2 h after administration and declined to below the level of quantification over 4-8 h after administration with an elimination half-life (T1/2) of 0.65 h. Slight reductions in heart rate and increases in sedation scores were seen in all treatment groups. In conclusion, obtained data indicated a single dose of clonidine RR at 0.05 mg/kg was well tolerated with mild sedation and bradycardia and no other adverse effects in healthy dogs.