Bioavailability of bupivacain from inclusion complexes with cyclodextrins. The study reports pharmacokinetic findings on the disposition of bupivacain (BP) inclusion complexes with 2-hydroxypropylo-b-cyclodextrin and b-cyclodextrin in rabbits as compared to plain BP after intramuscular administration. The experiment on healthy mixed breed rabbits of both sexes was carried out in the stages. In stage I the rabbits were administered intramuscular BP, in stage II - BP in 2-HP-b-Cd complex and in stage III - BP in b-Cd complex. The dose of BP used was 1 mg/kg body weight. Blood samples were collected at several time points up to 5 h after administration. Plasma concentration of BP were measured by gas chromatography with nitrogen-phosphorus detector. The area under the curve (AUC) and Cmaxwere smallest after injection of BP complexes especially when using b-Cd. This, together with highest apparent volume of distribution (Vdss) suggest a possible targetting anesthetic effects. Changed pharmacokinetic properities of BP in inclusion complexes are especially useful in local anaesthesia. In view of these findings, further investigation and assessment are worthwhile for future application in human subjects.