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Serum concentrations of tramadol enantiomers during patient-controlled analgesia. Br J Clin Pharmacol 1999 Aug;48(2):254-7



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Scopus ID

2-s2.0-0032775742 (requires institutional sign-in at Scopus site)   74 Citations


AIMS: Tramadol, a centrally acting analgesic, is used as a racemate containing 50% of a (+)- and 50% of a (-)-enantiomer. This paper presents the pharmacokinetic results of postoperative patient-controlled analgesia using (+)-tramadol, (-)-tramadol or the racemate.

METHODS: Ninety-eight patients recovering from major gynaecological surgery were treated in a randomised, double-blind study with (+)-tramadol, (-)-tramadol or the racemate. Following an i.v. bolus up to a maximum of 200 mg, patient-controlled analgesia with demand doses of 20 mg was made available for 24 h. Prior to each demand, the serum concentrations of the enantiomers of tramadol and its metabolite M1 were measured in 92 patients.

RESULTS: The mean concentrations of tramadol during the postsurgery phase were 470+/-323 ng ml-1, 590+/-410 ng ml-1 and 771+/-451 ng ml-1 in the (+)-, racemate- and (-)-group, respectively ((+) vs (-), P<0.05); the mean concentrations of the metabolite M1 were 57+/-18 ng ml-1, 84+/-34 ng ml-1 and 96+/-41 ng ml-1 in the (+)-, racemate- and (-)-group, respectively ((+) vs (-) and (+) vs racemate, P<0.05). The mean concentrations of (+)-tramadol and (+)-M1 were lower in the racemate- than in the (+)-group (P<0.05), those of (-)-tramadol and (-)-M1 were lower in the racemate than in the (-)-group (P<0.05). In the racemate group, the mean serum concentrations of (+)-tramadol were higher than those of (-)-tramadol (P<0.05), whereas the mean serum concentrations of (-)-M1 were higher than those of (+)-M1 (P<0. 05).

CONCLUSIONS: The therapeutic serum concentration of tramadol and M1 showed a great variability. The lowest mean concentrations were measured in the (+)-group and the highest in (-)-group. This is in agreement with the clinical finding that (+)-tramadol is a more potent analgesic than (-)-tramadol.

Author List

Grond S, Meuser T, Uragg H, Stahlberg HJ, Lehmann KA


Thomas Meuser MD Professor in the Anesthesiology department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Analgesia, Patient-Controlled
Analgesics, Opioid
Double-Blind Method
Gas Chromatography-Mass Spectrometry
Middle Aged
Pain, Postoperative