Concordance between tramadol and dextromethorphan parent/metabolite ratios: the influence of CYP2D6 and non-CYP2D6 pathways on biotransformation.

Cytochrome P4502D6 (CYP2D6) activity has been shown to be a determinant of both the pharmacokinetics and pharmacodynamics of tramadol in adults. This study evaluated the association between CYP2D6 activity, as determined by dextromethorphan (DM) urinary metabolite ratio, and tramadol biotransformation in 13 children (7-16 years). CYP2D6 genotype was determined by XL-PCR and PCR/RFLP. Phenotype was assessed by HPLC quantitation of DM and its metabolites from a 12- to 24-hour urine collection following a single oral dose of DM. There was only a modest correlation between tramadol/M1 (metabolite 1) plasma concentration or AUC and the DM/dextrorphan (DX) urinary molar ratio in the study cohort; however, when subjects were segregated based on the number of functional CYP2D6 alleles, a much stronger relationship was observed for subjects with two functional alleles, with essentially no relationship evident in those individuals with one functional allele. Further evaluation of these data suggested that the CYP2D6-mediated metabolite (M1) is formed to a lesser extent, and the formation of the non-CYP2D6 product (M2) is more pronounced in subjects with one versus two functional alleles. Thus, the number of functional CYP2D6 alleles and the availability of alternative cytochromes P450 capable of metabolizing tramadol may explain the poor association between DM, a well-characterized CYP2D6 probe, and tramadol in a population of CYP2D6 extensive metabolizers.

Tramadol and acetaminophen tablets for dental pain.

The purpose of this work was to compare the efficacy and time to analgesia of a new tramadol/acetaminophen combination tablet to those of tramadol or acetaminophen (APAP) alone. A meta-analysis was performed of 3 separate single-dose, double-blind, parallel-group trials in patients with moderate or severe pain following extraction of 2 or more third molars. Patients in each study were evenly randomized to a single dose of tramadol/APAP (75 mg/650 mg), tramadol 75 mg, APAP 650 mg, ibuprofen 400 mg, or placebo. Active control with ibuprofen was used to determine model sensitivity. Pain relief (scale, 0-4) and pain intensity (scale, 0-3) were reported at 30 minutes after the dose and then hourly for 8 hours. Total pain relief over 8 hours (TOTPAR8) and the sum of pain intensity differences (SPID8) were calculated from the hourly scores. Time to onset of pain relief was determined by the double-stopwatch technique, and patients were advised to wait at least 2 hours before taking supplemental analgesia. Patients assessed overall efficacy (scale, 1-5) upon completion. In all, 1197 patients (age range, 16-46 years) were evaluable for efficacy; treatment groups in each study were similar at baseline. Pain relief was superior to placebo (P < or = .0001) for all treatments. Pain relief provided by tramadol/ APAP was superior to that of tramadol or APAP alone, as shown by mean TOT-PAR8 (12.1 vs 6.7 and 8.6, respectively, P < or = .0001) and SPID8 (4.7 vs 0.9 and 2.7, respectively, P < or = .0001). Estimated onset of pain relief was 17 minutes (95% CI, 15-20 minutes) for tramadol/APAP compared with 51 minutes (95% CI, 40-70 minutes) for tramadol, 18 minutes (95% CI, 16-21 minutes) for APAP, and 34 minutes (95% CI, 28-44 minutes) for ibuprofen. Median time to supplemental analgesia and mean overall assessment of efficacy were greater (P < .05) for the tramadol/APAP group (302 minutes and 3.0, respectively) than for the tramadol (122 minutes and 2.0) or APAP (183 minutes and 2.7) monotherapy groups. A new combination analgesic, tramadol/APAP, is superior to tramadol or APAP alone with respect to pain relief and duration of action. It is also superior to tramadol alone with respect to time to onset.

Effects of aluminum and manganese on the growth of ectomycorrhizal fungi.

Cenococcum graniforme, Suillus luteus, Thelephora terrestris, and three isolates of Pisolithus tinctorius were cultured on modified Melin-Norkrans medium at pH 3.4 and adjusted to 0 to 500 ppm (0 to 500 mug/ml) of aluminum or manganese sulfate. Except for T. terrestris, which was intolerant of aluminum at 150 and 250 to 500 ppm, and P. tinctorius isolate 250, which was intolerant of aluminum at 450 ppm, all fungi showed some growth at all concentrations of aluminum. S. luteus was the most tolerant to aluminum. Manganese was less fungitoxic than aluminum, with all fungi showing at least 65% growth at 500 ppm as compared with the control. C. graniforme was not inhibited at any concentration of manganese, and S. luteus was only affected at 500 ppm. P. tinctorius isolate 230 showed no significant variation in growth when subjected to various concentrations of three forms of manganese salts. Significant differences in growth were detected in response to three aluminum salts, but no detectable pattern was apparent. Genotypic responses to aluminum and manganese were evident for P. tinctorius. Isolates 210 and 230 were more tolerant to manganese than was isolate 250. Aluminum tolerance was in the order of isolate 230 > 210 > 250. Results of in vitro studies concerning tolerance responses of ectomycorrhizal fungi to aluminum and manganese were not consistent with field observations of the successional sequence of these fungi on acid coal spoils.