Objective St John's Wort, a widely used herbal product, is an inducer of CYP3A4 and it decreases blood concentrations of CYP3A4 substrates. The effects of St John's Wort on the pharmacokinetics of 3‐hydroxy‐3‐methylglutaryl coenzyme A reductase inhibitors simvastatin (an inactive lactone pro‐drug) and pravastatin were determined in this study. Methods Sixteen healthy male subjects (n = 8 in group 1 and n = 8 in group 2) took a St John's Wort caplet (300 mg) or matching placebo three times a day for 14 days in a double‐blind, crossover study. On day 14, a single oral dose of 10 mg simvastatin and 20 mg pravastatin was given to subjects in group 1 and group 2, respectively. Blood samples were obtained during a 24‐hour period after the administration of each drug. Results Repeated St John's Wort treatment tended to lower plasma simvastatin concentration and significantly (P < .05) lowered concentrations of simvastatin hydroxy acid, its active metabolite. The peak concentration in plasma (ratio, 0.72 of placebo) of simvastatin hydroxy acid tended to be decreased and its area under the plasma concentration‐time curve between time zero and 24 hours after administration (ratio, 0.48 of placebo) was significantly decreased (P < .05) by St John's Wort. On the other hand, St John's Wort did not influence plasma pravastatin concentration. No significant differences were observed in the elimination half‐life of simvastatin or pravastatin between the placebo and St John's Wort trials. Conclusions This study showed that St John's Wort decreases plasma concentrations of simvastatin but not of pravastatin. Because simvastatin is extensively metabolized by CYP3A4 in the intestinal wall and liver, which are induced by St John's Wort, it is likely that this interaction is partly caused by the enhancement of the CYP3A4‐mediated first‐pass metabolism of simvastatin in the small intestine and liver. Clinical Pharmacology & Therapeutics (2001) 70, 518–524; doi:

This article is available online at http://dmd.aspetjournals.org ABSTRACT:In this case report, we present genetic differences in two morphine-related gene sequences, UDP-glucuronosyltransferase 2B7 (UGT2B7) and opioid receptors (MOR1), in two cancer patients whose clinical responses to morphine were very different [i.e., sensitive (patient 1) and low responder (patient 2)]. In addition, allelic variants in the UGT2B7 gene were analyzed in 46 Japanese individuals. Amplified DNA fragments for the two genes of interest were screened using single strand conformation polymorphism and then sequenced. In the UGT2B7 gene, 12 single nucleotide polymorphisms (SNPs) were newly identified with an allelic frequency ranging from 0.022 to 0.978. Six SNPs in the promoter region (A-1302G, T-1295C, T-1111C, G-899A, A-327G, and T-125C) and two coding SNPs (UGT2B7*2 in exon 2 and C1059G in exon 4) appeared to be consistently linked. Remarkable differences in the nucleotide sequence of UGT2B7 were observed between the two patients; in contrast to patient 1 who had "reference" alleles at almost SNP positions, but a rare ATTGAT*2(AT)C haplotype as homozygosity, patient 2 was a homozygous carrier for the predominant GCCAGC*1(TC)G sequence. Serum morphine and two glucuronide concentrations in patient 2 suggest that the predominant GCCAGC*1G sequence was not associated with a "poor metabolizer" phenotype. In the MOR1 gene, patient 1 had no SNPs, whereas patient 2 was a heterozygous carrier for both the G-1784A and A118G alleles. The present study describes substantial differences in genotype patterns of two genes of interest between the two patients. The results necessitate larger trials to confirm these observations in larger case control studies.

No abstract

There is a significant difference in the incidence of docetaxel-induced severe neutropenia between Asian and non-Asian clinical studies. Physicians and pharmacists should consider ethnic diversity in docetaxel toxicity when interpreting the results of clinical trials.