V. Piguet et al., LACK OF ACETAMINOPHEN CEILING EFFECT ON R-III NOCICEPTIVE FLEXION REFLEX, European Journal of Clinical Pharmacology, 53(5), 1998, pp. 321-324
Objective: The analgesic efficacy of intravenous doses of acetaminophe
n (paracetamol) 0.5 g, 1 g and 2 g (administered as propacetamol) was
assessed in 11 healthy subjects in a randomised, double-blind, placebo
-controlled crossover study. The antinociceptive effect was assessed o
ver 8 h by measurement of the nociceptive flexion rifler threshold (R-
III) in response to selective transcutaneous electrical stimulations.
Results: After acetaminophen 0.5 g, R-III increased to a mean maximum
of 23% over baseline values; after 1 g to 28%, and after 2 g to 40%. T
he AUC(0-8) h of the analgesic effects and the AUC(0-8) h of plasma co
ncentrations closely correlated and were dose-dependent: r(s) = 0.37,
for R-III and r(s) = 0.94, for the plasma concentrations. Intravenous
acetaminophen exerted a dose-dependent central antinociceptive effect.