Therapeutic drug monitoring
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Comparative Study Clinical Trial Controlled Clinical Trial
Effect of route of administration on the pharmacokinetic behavior of enantiomers of nefopam and desmethylnefopam.
Nefopam hydrochloride is a non-narcotic analgesic used parenterally and orally as a racemic mixture for the relief of postoperative pain. However, no information is presently available on the oral kinetics of (+) and (-) nefopam in humans. Also, nefopam is metabolized by N-demethylation but it is not known whether the desmethylnefopam enantiomers (DES1 and DES2) are present in plasma following intravenous (I. ⋯ V. and oral administration, desmethylnefopam enantiomers showed stereoselectivity in AUC and Cmax values. Urinary excretion of parent and metabolite enantiomers was less than 5% of dose. This study shows that desmethylnefopam enantiomers can contribute to the analgesic effect of racemic nefopam only when it is administered orally.