The effect of gender on changes of pharmacokinetic parameters of thiopental with combined phenylbutazone in stray dogs

Objectives: NSAIDs have the potential for both pharmacokinetic and pharmacodynamic interactions with injectable anesthetic drugs through protein binding and analgesic interactions. Our objective was to deternine whether sex and drug interaction on chenges of pharmacokinetic parameters of thiopental in dog.Materials Methods. Sixteen female and sixteen male dogs were randomly divided into two sub-groups. Normal saline (0.1 ml/kg) and thiopental sodium 5% (0.17 mg/kg) were intravenously (i.v.) administered to animals in the control group. Equivalent dose of thiopental sodium was administered following the injection of phenylbutazone 20% (0.1 ml/kg) via the same route and blood sample collected 9 times. Thiopental concentration was measured using HPLC method in serum. Recovery period and the pharmacokinetics parameters (Kel, t1/2, Vd, Cl) were calculated by non-compartmental analysis of the concentration-time curves.Results: Results of this study showed that there are significant differences in the rate of elimination, half-life, volume distribution and clearance of thiopental between experimental and control sub-groups of tow gender (P 0.05).Conclusion: Phenylbutazon displaced thiopental can normally distribute out of the plasma compartment causes an increase in the unbound form of thiopental and chenges pharmacokinetic parameters. Female dogs have generally less of lean body mass and requires less thiopental than male dogs to lose consciousness.,