[Elimination half life of the opiate etorphine]

In the capacity of an initial study both, the pharmacocinetics as well as the metabolism of etorphine were investigated. In a self-trial a bolus of 8 micrograms tritium-marked etorphine as administered intravenously and subsequently the half-lives in serum and urine were determined. To achieve this, etorphine and etorphineclucuronide were separated via HPLC and then quantified by measuring the radioactivity. The development of the concentrations was devided into 3 phases. Within the first phase half-lives of etorphine and etorphineglucuronide were found in the range of 0.3-1 hour in serum and, likewise, in urine. During the second phase the estimated half-life of etorphineglucuronide was 160-260 hours in serum as well as in urine. Within the last phase half-lives in urine were 47 hours for etorphine and 41 hours for etorphineglucuronide while the calculation of the half-lives in serum was not sufficiently feasible.