Pharmacogenetic Associations with ADME Variants and Virologic Response to an Initial HAART Regimen in HIV-Infected Women.

BACKGROUND: Clinical response to highly active antiretroviral therapy (HAART) varies among different populations. A portion of this variability may be due to variation in genes involved in the absorption, distribution, metabolism, and excretion (ADME) of HAART. DESIGN: To identify genetic factors involved in virologic responses to HAART, 13 genes in ADME pathways were analyzed in a cohort of HIV-infected women on HAART. A total of 569 HIV-positive participants from the Women's Interagency HIV Study who initiated HAART from 1994-2012 and had genotype data were included in these analyses. METHODS: Admixture maximum likelihood burden testing was used to evaluate gene-level associations between common genetic variation and virologic response (achieving <80 viral copies/mL) to HAART overall and with specific drug classes. Results: Six statistically significant (P<0.05) gene-level burden tests were observed with response to specific regimen types. CYP2B6, CYP2C19 and CYP2C9 were significantly associated with response to protease inhibitor (PI)-based regimens. CYP2C9, ADH1A and UGT1A1 were significantly associated with response to triple nucleoside reverse transcriptase inhibitor (NRTI) treatment. CONCLUSIONS: Although no genome-wide associations with virologic response to HAART overall were detected in this cohort of HIV-infected women, more statistically significant gene-level burden tests were observed than would be expected by chance (two and a half expected, six observed). It is likely that variation in one of the significant genes is associated with virologic response to certain HAART regimens. Further characterization of the genes associated with response to PI-based treatment is warranted.

A screening study of drug-drug interactions in cerivastatin users: an adverse effect of clopidogrel.

An analysis of a case-control study of rhabdomyolysis was conducted to screen for previously unrecognized cytochrome P450 enzyme (CYP) 2C8 inhibitors that may cause other clinically important drug-drug interactions. Medication use in cases of rhabdomyolysis using cerivastatin (n = 72) was compared with that in controls using atorvastatin (n = 287) for the period 1998-2001. The use of clopidogrel was strongly associated with rhabdomyolysis (odds ratio (OR) 29.6; 95% confidence interval (CI), 6.1-143). In a replication effort that used the US Food and Drug Administration (FDA) Adverse Event Reporting System (AERS), it was found that clopidogrel was used more commonly in patients with rhabdomyolysis receiving cerivastatin (17%) than in those receiving atorvastatin (0%, OR infinity; 95% CI = 5.2-infinity). Several medications were tested in vitro for their potential to cause drug-drug interactions. Clopidogrel, rosiglitazone, and montelukast were the most potent inhibitors of cerivastatin metabolism. Clopidogrel and its metabolites also inhibited cerivastatin metabolism in human hepatocytes. These epidemiological and in vitro findings suggest that clopidogrel may cause clinically important, dose-dependent drug-drug interactions with other medications metabolized by CYP2C8.