PHARMACY PRACTICE Antiretroviral Therapeutic Drug Monitoring in Canada: Current Status and Recommendations for Clinical Practice

Therapeutic drug monitoring (TDM) is a strategy whereby the plasma concentration of one or more drugs is measured and drug doses are adjusted accordingly to achieve concentrations within an acceptable therapeutic range. Th

Correlates of efavirenz exposure in chilean patients affected with human immunodeficiency virus reveals a novel association with a polymorphism in the constitutive androstane receptor

OBJECTIVE: To explore the effect of demographics and single-nucleotide polymorphisms in cytochrome P450 (CYP) 2B6, 2A6, UDP-glucuronosyltransferase (UGT) 2B7, and the constitutive androstane receptor (CAR) genes on efavirenz pharmacokinetics in a Chilean cohort affected with human immunodeficiency virus. METHODS: Timed plasma samples obtained throughout the dosing interval were analyzed for efavirenz concentrations with liquid chromatography/tandem mass spectrometry. DNA from whole-blood samples was used for genetic analysis. Data were analyzed using a Mann-Whitney statistical test; furthermore, a Pearson or Spearman correlation was used. A multivariate analysis was then conducted using multiple linear regression by best subset analysis. RESULTS: Overall 219 patients were included, 208 patients had measurable efavirenz levels and available genetic samples. The overall median (interquartile range) of efavirenz concentration was 2.6 (2.1-3.7) mcg/mL. In multivariate regression analysis

A retrospective TDM database analysis of interpatient variability in the pharmacokinetics of lopinavir in HIV-infected adults.

Contains fulltext : 49562.pdf (publisher's version ) (Closed access)Lopinavir is one of the most-widely used protease inhibitors in the treatment of HIV-1 infected patients. Concentration-effect relationships have been described for both antiviral activity and toxicity. Less is known about patient characteristics that may determine interpatient variability in lopinavir plasma concentrations. A database was created containing all Therapeutic Drug Monitoring (TDM) results collected at our Department. Patients were included if they were using lopinavir twice daily for at least two weeks; subjects who were known to be nonadherent (based on either a lopinavir concentration <0.2 mg/L or suspected by the physician) were excluded. Demographic data were collected from TDM application forms and patient charts. Patients attending one of the 22 HIV treatment centers in The Netherlands. The Department of Clinical Pharmacy is a national referral center for TDM of antiretroviral agents. Lopinavir concentration ratios (CRs) were calculated for each patient by dividing the individual plasma concentration by the time-adjusted population value. Relationships with lopinavir CRs were tested using regression analysis and analysis of variance. A total of 802 patients were included (607 males; 150 females; 45 unknown). The age and body weight of the patients ranged from 18 to 74 years (mean 42) and 42 to 121 kg (mean 72), respectively. Race was known for 756 persons: Caucasian 76%, African 18% and Asian 6%. The median (+ interquartile range, IQR) lopinavir CR was 0.98 (IQR: 0.67-1.31). Body weight showed an inverse relationship with lopinavir CR (F = 23.1; P < 0.001). Age was not related with lopinavir CR (P = 0.99). Female patients had a significantly higher lopinavir CR than males: 1.18 vs. 1.03 (P = 0.005); race was not associated with differences in lopinavir CR. In a multivariate regression analysis body weight, but not gender, remained significantly related to lopinavir CR. Body weight is the only demographic factor that could be related to lopinavir exposure; clinicians should be alert for an increased risk of suboptimal antiviral efficacy in patients with high body weight, and for an increased risk of toxicity in patients with a low body weight

Factors affecting antiretroviral pharmacokinetics in HIV-infected women with virologic suppression on combination antiretroviral therapy: a cross-sectional study

Abstract Background Although some studies show higher antiretroviral concentrations in women compared to men, data are limited. We conducted a cross-sectional study of HIV-positive women to determine if protease inhibitor (PI) and non-nucleoside reverse transcriptase inhibitor (NNRTI) Cmin and Cmax values were significantly different than historical general population (predominantly male) averages and to evaluate correlates of higher concentrations. Methods HIV-positive women with virologic suppression (viral load < 50copies/mL) on their first antiretroviral regimen were enrolled. Timed blood samples for Cmin and Cmax were drawn weekly for 3 weeks. The ratio of each individual’s median Cmin and Cmax to the published population mean values for their PI or NNRTI was calculated and assessed using Wilcoxon sign-rank. Intra- and inter-patient variability of antiretroviral drug levels was assessed using coefficient of variation and intra-class correlation. Linear regression was used to identify correlates of the square root-transformed Cmin and Cmax ratios. Results Data from 82 women were analyzed. Their median age was 41 years (IQR=36-48) and duration of antiretrovirals was 20 months (IQR=9-45). Median antiretroviral Cmin and Cmax ratios were 1.21 (IQR=0.72-1.89, p=0.003) (highest ratios for nevirapine and lopinavir) and 0.82 (IQR=0.59-1.14, p=0.004), respectively. Nevirapine and efavirenz showed the least and unboosted atazanavir showed the most intra- and inter-patient variability. Higher CD4+ count correlated with higher Cmin. No significant correlates for Cmax were found. Conclusions Compared to historical control data, Cmin in the women enrolled was significantly higher whereas Cmax was significantly lower. Antiretroviral Cmin ratios were highly variable within and between participants. There were no clinically relevant correlates of drug concentrations. Trial registration NCT0043397

Factors affecting antiretroviral pharmacokinetics in HIV-infected women with virologic suppression on combination antiretroviral therapy: a cross-sectional study

Background: Although some studies show higher antiretroviral concentrations in women compared to men, data are limited. We conducted a cross-sectional study of HIV-positive women to determine if protease inhibitor (PI) and non-nucleoside reverse transcriptase inhibitor (NNRTI) Cmin and Cmax values were significantly different than historical general population (predominantly male) averages and to evaluate correlates of higher concentrations. Methods: HIV-positive women with virologic suppression (viral load < 50copies/mL) on their first antiretroviral regimen were enrolled. Timed blood samples for Cmin and Cmax were drawn weekly for 3 weeks. The ratio of each individual’s median Cmin and Cmax to the published population mean values for their PI or NNRTI was calculated and assessed using Wilcoxon sign-rank. Intra- and inter-patient variability of antiretroviral drug levels was assessed using coefficient of variation and intra-class correlation. Linear regression was used to identify correlates of the square root-transformed Cmin and Cmax ratios. Results: Data from 82 women were analyzed. Their median age was 41 years (IQR=36-48) and duration of antiretrovirals was 20 months (IQR=9-45). Median antiretroviral Cmin and Cmax ratios were 1.21 (IQR=0.72-1.89, p=0.003) (highest ratios for nevirapine and lopinavir) and 0.82 (IQR=0.59-1.14, p=0.004), respectively. Nevirapine and efavirenz showed the least and unboosted atazanavir showed the most intra- and inter-patient variability. Higher CD4+ count correlated with higher Cmin. No significant correlates for Cmax were found. Conclusions: Compared to historical control data, Cmin in the women enrolled was significantly higher whereas Cmax was significantly lower. Antiretroviral Cmin ratios were highly variable within and between participants. There were no clinically relevant correlates of drug concentrations. Trial registration: NCT00433979Anesthesiology, Pharmacology and Therapeutics, Department ofInfectious Diseases, Division ofMedicine, Department ofMedicine, Faculty ofReviewedFacult