The objective of the investigations described in this thesis was to characterize the in vivo pharmacological and PK-PD properties of buprenorphine relative to fentanyl with respect to: 1) kinetics... Show moreThe objective of the investigations described in this thesis was to characterize the in vivo pharmacological and PK-PD properties of buprenorphine relative to fentanyl with respect to: 1) kinetics of onset and offset of the pharmacological effects at the mu-opioid receptor, 2) selectivity of action (antinociception versus respiratory depression), 3) the interspecies extrapolation of the PK-PD correlation of the antinociceptive and respiratory depressant effect, 4) the role of active metabolites, 5) kinetics of antagonism of the respiratory depressant effect. Preclinical investigations were performed to develop and validate mechanism-based PK-PD models for the effects of opioids on antinociception and respiration. These PK-PD models were subsequently applied to characterize the effects of buprenorphine and fentanyl in humans. It was shown that the developed PK-PD model can be used to predict the efficacy and safety outcome of opioids in animals. Furthermore, the PK-PD model had excellent properties to enable animal-to-human extrapolation of the efficacy and safety outcome. Show less