Veng-Pedersen P, Wilhelm JA, Zakszewski TB, Osifchin E, Waters SJ. Duration of opioid antagonism by nalmefene and naloxone in the dog: an integrated pharmacokinetic/pharmacodynamic comparison.
J Pharm Sci 1995;
84:1101-6. [PMID:
8537889 DOI:
10.1002/jps.2600840913]
[Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
A continuous fentanyl infusion was administered to eight adult, male beagle dogs for a duration of approximately 400 min at a rate of 30 micrograms/kg/h. The extent of respiratory depression was quantified by continuous, noninvasive, transcutaneous pCO2 recordings. Upon reaching a pseudosteady-state of respiratory depression at approximately 120 min of fentanyl infusion, the animals then received, in a 2 x 2 crossover fashion separated by approximately 3 weeks, 30-minute equiefficacious infusions of nalmefene (12 micrograms/kg/h) or naloxone (48 micrograms/kg/h). Multiple venous blood samples were taken throughout the dosing regimen, and the resulting fentanyl, nalmefene, or naloxone plasma concentrations were determined. The concentration-time data were analyzed by noncompartmental methods and subsequently linked to the pharmacodynamic effect data by a competitive antagonism link model. Separately, the biophase concentrations were linked to the plasma concentration-time profiles through a single-exponential conduction function. The various pharmacokinetic/pharmacodynamic parameters resulting from this semiparametric analysis were analyzed by ANOVA, using a statistical model that considers carryover effects. The results of these analyses indicate that several pharmacokinetic/pharmacodynamic parameters of the two antagonists were comparable. However, nalmefene had a significantly more protracted terminal disposition and a significantly greater persistency in the biophase evaluated over the experimental time frame from 0 to 450 min.
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