Summary
The pharmacokinetic constants and rectal bioavailability of the narcotic analgesic ketobemidone were determined in six male patients after surgery. Plasma concentrations were measured following intravenous administration of Ketogin® 2 ml, containing ketobemidone chloride 10 mg, and a spasmolytic compound N,N-dimethyl-3,3-diphenyl-1-methylallylamine chloride 50 mg, and following rectal administration of one suppository of Ketogin®, containing ketobemidone chloride 10 mg and the spasmolytic component 50 mg. Following intravenous administration, the disposition of ketobemidone followed a biexponential pattern with a fast distribution phase and a slower elimination phase: the plasma half-life (t1/2β) was 2.42±0.41 h (rodel ± SD). After rectal administration, the disposition of ketobemidone fitted a one-compartment model. The elimination half-life was 3.27±0.32 h. The mean rectal bioavailability for ketobemidone was 44%±9%. The pharmacokinetic constants of the spasmolytic component, N,N-dimethyl-3,3-diphenyl-1-methylallylamine, were also determined in five of the patients, both after intravenous and after rectal administration. The plasma half-life was 3.07±0.53 h and 3.79±1.14 h, respectively. The rectal bioavailability was estimated to be 33%±14%.
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Anderson, P., Arnér, S., Bondesson, U. et al. Clinical pharmacokinetics of ketobemidone. Its bioavailability after rectal administration. Eur J Clin Pharmacol 19, 217–223 (1981). https://doi.org/10.1007/BF00561953
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DOI: https://doi.org/10.1007/BF00561953