CYP2B6 haplotype and biological factors responsible for hepatotoxicity in HIV-infected patients receiving efavirenz-based antiretroviral therapy.

Data on the pharmacogenetic markers of CYP2B6 and biological factors associated with hepatotoxicity in HIV-infected patients receiving an efavirenz-based antiretroviral therapy (ART) regimen are very limited. A total of 134 HIV-infected Thai adults were prospectively enrolled to receive a once-daily regimen of efavirenz 600 mg/tenofovir/lamivudine. Seven single nucleotide polymorphisms (SNPs) within CYP2B6 were genotyped using real-time PCR. At 12 weeks after ART, plasma efavirenz concentrations at 12h after dosing were measured. The mean ± standard deviation patient age was 37 ± 8 years, and 77.6% were male. The median (IQR) CD4 count was 43 cells/mm(3) (17-105 cells/mm(3)). Eighteen patients (13.4%) had positive anti-HCV and 5 patients (3.7%) had positive HBsAg. The frequencies of heterozygous/homozygous mutants of each SNP were 64C>T (11%), 499C>G (0%), 516G>T (55%), 785A>G (63%), 1375A>G (0%), 1459C>T (3%) and 21563C>T (62%). The three most frequent haplotypes identified included *1/*6 (40.3%), *1/*1 (34.3%) and *6/*6 (8.2%). The median (IQR) plasma efavirenz concentration was 2.3mg/L (1.4-3.7 mg/L). At 24 weeks, median (IQR) serum ALP was 98 mg/dL (73-133 mg/dL) and direct bilirubin was 0.11 mg/dL (0.10-0.19 mg/dL). The proportion of grade 1 and grade 2 elevated serum ALP was 12.7% and 1.5%, respectively. By multivariate analysis, factors associated with high ALP, total bilirubin and direct bilirubin included CYP2B6 haplotype *6/*6, high serum ALP at Week 0 and positive anti-HCV (all P<0.05). In summary, HIV-infected patients with the pharmacogenetic marker 'CYP2B6 haplotype *6/*6' may have increased susceptibility to hepatotoxicity with efavirenz-based ART.

Impact of pharmacogenetic markers of CYP2B6, clinical factors, and drug-drug interaction on efavirenz concentrations in HIV/tuberculosis-coinfected patients.

Comprehensive information on the effects of cytochrome P450 2B6 (CYP2B6) polymorphisms, clinical factors, and drug-drug interactions on efavirenz concentrations in HIV/tuberculosis-coinfected (HIV/TB) patients is unavailable. A total of 139 HIV/TB adults, 101 of whom received a rifampin-containing anti-TB regimen, were prospectively enrolled to receive efavirenz (600 mg)/tenofovir/lamivudine. Nine single nucleotide polymorphisms (SNPs) within CYP2B6 were genotyped. Plasma efavirenz concentrations were measured at 12 weeks. The median (interquartile range [IQR]) efavirenz concentration was 2.3 (1.4 to 3.9) mg/liter. The SNPs (frequencies of heterozygous and homozygous mutants) were 64C>T (10% and 1%), 499C>G (0% and 0%), 516G>T (47% and 8%), 785A>G (54% and 10%), 1375A>G (0% and 0%), 1459C>T (3% and 0%), 3003C>T (44% and 27%), 18492T>C (39% and 6%), and 21563C>T (57% and 5%). The four most frequent CYP2B6 haplotypes identified were *1/*6 (41%), *1/*1 (35%), *1/*2 (7%), and *6/*6 (7%). The heterozygous/homozygous mutation associated with low efavirenz concentrations was 18492T>C (P < 0.001), and those associated with high efavirenz concentrations were 516G>T, 785A>G, and 21563C>T (all P < 0.05). Haplotype *1/*1 was associated with low efavirenz concentrations, and *6/*6, *1/*6, and *5/6 were associated with high efavirenz concentrations. As shown by multivariate analysis, low efavirenz concentrations were significantly associated with the *1/*1 haplotype (beta = -1.084, P = 0.027) and high body weight (beta = -0.076, P = 0.002). In conclusion, pharmacogenetic markers of CYP2B6 have the greatest impact with respect to inducing low plasma efavirenz concentrations in HIV/TB Thai patients.

Time to initiate antiretroviral therapy between 4 weeks and 12 weeks of tuberculosis treatment in HIV-infected patients: results from the TIME study.

BACKGROUND: Optimal timing for initiation of antiretroviral therapy (ART) among HIV-infected patients with tuberculosis (TB) is not well established. METHODS: HIV/TB-coinfected patients were randomized to initiate tenofovir/lamivudine/efavirenz at 4 weeks (4-week group) or 12 weeks (12-week group) of TB treatment. The primary outcome was 1-year all-cause mortality. RESULTS: Of 156 patients, 79 were in 4-week group and 77 in 12-week group. Overall, median (interquartile range) CD4 was 43 (47-106) cells per cubic millimeter and median (interquartile range) HIV-1 RNA was 5.8 (5.4-6.3) log copies per milliliter. Eleven (7%) mortalities occurred in a total follow-up period of 137 patient-years. Seven percent (6/79, 8.76 per 100 patient-years) mortalities were in 4-week group, and 6% (5/77, 7.25 per 100 person-years) mortalities were in 12-week group [relative risk (RR) = 0.845, 95% confidence interval (CI) = 0.247 to 2.893]. Twenty-eight (35%) patients in 4-week group and 25 (32%) patients in 12-week group were hospitalized (RR = 1.142, 95% CI = 0.588 to 2.217). Grade 2-4 adverse events were 39% (31/79) in 4-week group and 34% (26/77) in 12-week group (RR = 1.267, 95% CI = 0.659 to 2.435). In multivariate analysis, "low albumin" (RR = 2.695, 95% CI = 1.353 to 5.475) and "low baseline CD4 count" (RR = 4.878, 95% CI = 1.019 to 23.256) were the independent predictors of mortality. Immune reconstitution inflammatory syndrome was more frequent in 4-week group with an incidence of 8.86 versus 5.02 per 100 person-months in 12-week group over the first 6 months of ART (P = 0.069). CONCLUSIONS: In middle-income countries where ART is initiated at CD4 count of <350 cells per cubic millimeter, immediate initiation of ART in HIV-infected patients with active TB was not associated with survival advantage when compared to initiation of ART at 12 weeks.

Renal impairment after switching from stavudine/lamivudine to tenofovir/lamivudine in NNRTI-based antiretroviral regimens.

BACKGROUND: During stavudine phase-out plan in developing countries, tenofovir is used to substitute stavudine. However, knowledge regarding whether there is any difference of the frequency of renal injury between tenofovir/lamivudine/efavirenz and tenofovir/lamivudine/nevirapine is lacking. METHODS: This prospective study was conducted among HIV-infected patients who were switched NRTI from stavudine/lamivudine to tenofovir/lamivudine in efavirenz-based (EFV group) and nevirapine-based regimen (NVP group) after two years of an ongoing randomized trial. All patients were assessed for serum phosphorus, uric acid, creatinine, estimated glomerular filtration rate (eGFR), and urinalysis at time of switching, 12 and 24 weeks. RESULTS: Of 62 patients, 28 were in EFV group and 34 were in NVP group. Baseline characteristics and eGFR were not different between two groups. At 12 weeks, comparing mean ± SD measures between EFV group and NVP group were: phosphorus of 3.16 ± 0.53 vs. 2.81 ± 0.42 mg/dL (P = 0.005), %patients with proteinuria were 15% vs. 38% (P = 0.050). At 24 weeks, mean ± SD phosphorus and median (IQR) eGFR between the corresponding groups were 3.26 ± 0.78 vs. 2.84 ± 0.47 mg/dL (P = 0.011) and 110 (99-121) vs. 98 (83-112) mL/min (P = 0.008). In NVP group, comparing week 12 to time of switching, there was a decrement of phosphorus (P = 0.007) and eGFR (P = 0.034). By multivariate analysis, 'receiving nevirapine', 'old age' and 'low baseline serum phosphorus' were associated with hypophosphatemia at 24 weeks (P < 0.05). Receiving nevirapine and low baseline eGFR were associated with lower eGFR at 24 weeks (P < 0.05). CONCLUSION: The frequency of tenofovir-associated renal impairment was higher in patients receiving tenofovir/lamivudine/nevirapine compared to tenofovir/lamivudine/efavirenz. Further studies regarding patho-physiology are warranted.

Clinical case definition and manifestations of paradoxical tuberculosis-associated immune reconstitution inflammatory syndrome.

BACKGROUND: The International Network for the Study of HIV-associated IRIS (INSHI) recently published criteria for tuberculosis-associated immune reconstitution inflammatory syndrome (TB-IRIS) diagnosis. The performance of this definition and clinical manifestations of TB-IRIS were studied. METHODS: Antiretroviral therapy-naive HIV/TB Thai patients receiving antituberculous therapy were enrolled during 2006-2007 and prospectively followed through 24 weeks of antiretroviral therapy. Patients were defined as having paradoxical TB-IRIS if they fulfilled the 'study definition' by French 2004 and were confirmed by an external reviewer. All were later compared by the classification according to 'INSHI-2008'. RESULTS: For the 126 patients, median baseline CD4 cell count was 43 cells/microl and HIV-1 RNA was 5.9 log(10) Y copies/ml. Seventy-three (58%) had extrapulmonary/disseminated TB. Twenty-two (18%) and 21 (17%) fulfilled TB-IRIS criteria according to the study definition and INSHI-2008 definition, respectively. Two (2%) were diagnosed by study definition only and one (1%) by INSHI-2008 definition only. Twenty (16%) were concordantly diagnosed by both definitions and 103 (82%) were consistently negative. Eighteen (82%) had worsening of a preexisting site, whereas four (18%) had TB-IRIS in a new location. Lymph node enlargement (73%) and fever (59%) were common in TB-IRIS. Sensitivity and specificity of INSHI-2008 was 91% (95% confidence interval, 72-98%) and 99% (95% confidence interval, 95-99.8%), respectively. Positive predictive value was 95% and negative predictive value was 98%. By multivariate analysis, factors predicting TB-IRIS were extrapulmonary TB (odds ratio, 8.63) and disseminated TB (odds ratio, 4.17). CONCLUSION: There was high concordance between the INSHI-2008 and French 2004 definition for TB-IRIS diagnosis in HIV/TB patients with relatively high rate of paradoxical TB-IRIS. This suggests that lack of HIV-1 RNA and CD4 cell count monitoring does not impede the ability to diagnose TB-IRIS.

Body weight cutoff for daily dosage of efavirenz and 60-week efficacy of efavirenz-based regimen in human immunodeficiency virus and tuberculosis coinfected patients receiving rifampin.

Seventy-one human immunodeficiency virus-infected patients with tuberculosis who were receiving a rifampin (rifampicin)-containing regimen were initiated on treatment with efavirenz at 600 mg/day plus stavudine-lamivudine. Fasting efavirenz concentrations at 12 h after dosing (C12) were monitored. The mean +/- standard deviation efavirenz C12 at weeks 6 and 12 and after rifampin discontinuation were 4.5 +/- 4.3, 3.8 +/- 3.5, and 3.5 +/- 2.7 mg/liter, respectively. High body weight was associated with a low efavirenz C12 at weeks 6 and 12 (P = 0.003, r = -0.255). The efavirenz C12 regression prediction line at 1 mg/liter intercepted a mean body weight of 57.5 kg.

A randomized trial comparing plasma drug concentrations and efficacies between 2 nonnucleoside reverse-transcriptase inhibitor-based regimens in HIV-infected patients receiving rifampicin: the N2R Study.

BACKGROUND: To our knowledge, to date, no prospective, randomized, clinical trial has compared standard doses of efavirenz- and nevirapine-based antiretroviral therapy among patients with concurrent human immunodeficiency virus type 1 (HIV-1) infection and tuberculosis (TB) who are receiving rifampicin. METHODS: Rifampicin recipients with concurrent HIV-1 infection and TB were randomized to receive antiretroviral therapy that included either efavirenz (600 mg per day) or nevirapine (400 mg per day). Efavirenz and nevirapine concentrations at 12 h after dosing (C12) were monitored at weeks 6 and 12. CD4+ cell counts and HIV-1 RNA levels were assessed every 12 weeks. RESULTS: One hundred forty-two patients were randomized into 2 groups equally. The mean body weight of patients was 53 kg, the mean CD4+ cell count was 65 cells/mm3, and the median HIV-1 RNA level was 5.8 log10 copies/mL. At weeks 6 and 12, the mean C12 of efavirenz (+/- standard deviation) were 4.27+/-4.49 and 3.54+/-3.78 mg/L, respectively, and those for nevirapine were 5.59+/-3.48 and 5.6+/-2.65 mg/L, respectively. Interpatient variability in the efavirenz group was 2.3-fold greater than that in the nevirapine group (coefficient of variation, 107% vs. 47%). At week 12, 3.1% of patients in the efavirenz group and 21.3% in the nevirapine group had C12 values that were less than the recommended minimum concentrations (odds ratio, 8.396; 95% confidence interval, 1.808-38.993; P= .002). Intention-to-treat analysis revealed that 73.2% and 71.8% of patients in the efavirenz and nevirapine groups, respectively, achieved HIV-1 RNA levels <50 copies/mL at week 48, with respective mean CD4+ cell counts of 274 and 252 cells/mm3 (P> .05). Multivariate analysis revealed that patients with low C12 values and those with a body weight <55 kg were 3.6 and 2.4 times more likely, respectively, to develop all-cause treatment failure (P< .05). CONCLUSIONS: Antiretroviral therapy regimens containing efavirenz (600 mg per day) were less compromised by concomitant use of rifampicin than were those that contained nevirapine (400 mg per day) in patients with concurrent HIV-1 infection and TB. Low drug exposure and low body weight are important predictive factors for treatment failure.

Incidence and risk factors of nevirapine-associated severe hepatitis among HIV-infected patients with CD4 cell counts less than 250 cells/microL.

OBJECTIVES: To determine incidence and risk factors of nevirapine (NVP)-associated severe hepatitis that led to NVP discontinuation among HIV-infected patients with CD4 < 250 cells/microL. MATERIAL AND METHOD: A retrospective cohort study was conducted among antiretroviral-naïve HIV-infected patients who had baseline CD4 < 250 cells/microL and were initiated NVP-based antiretroviral therapy (ART) between January 2003 and October 2005. All patients were categorized to group A: occurred clinical hepatitis and group B: did not occur clinical hepatitis. All were followed until 6 months after ART. RESULTS: There were 910 patients with a mean age of 35.4 years, 57% were males and median (IQR) CD4 cell count was 27 (9-80) cells/microL; contributing 5,006 person-months of observations. Ten (1.1%) patients were in group A and 900 (98.9%) patients were in group B. Incidence of clinical hepatitis was 2 per 1,000 person-months. Probabilities of clinical hepatitis at 0.5, 1, 2, 3 and 6 months after ART were 0.2%, 0.5%, 0.7%, 0.8% and 1.1%, respectively. By Cox regression analysis, baseline AST > or = 1.5 times of upper limit was associated with higher incidence of clinical hepatitis (p = 0.019, HR = 5.83, 95% CI = 1.33-25.51). CONCLUSION: Incidence of NVP-associated severe hepatitis that lead to NVP discontinuation among HIV-infected patients with baseline CD4 < 250 cells/microL is low. The higher baseline AST is also associated with a higher risk of severe hepatitis.

Incidence and risk factors of nevirapine-associated skin rashes among HIV-infected patients with CD4 cell counts <250 cells/microL.

The objective of the study was to determine cumulative incidence and risk factors of nevirapine (NVP)-associated rashes that lead to NVP discontinuation among HIV-infected patients with CD4 <250 cells/microL. A retrospective cohort study was conducted among antiretroviral-naïve HIV-infected patients who had baseline CD4 <250 cells/microL and were initiated NVP-based antiretroviral therapy (ART) between January 2003 and October 2005. There were 910 patients with a mean age of 35.4 years and 43% were women. Median CD4 cell count was 27 cells/microL and median HIV RNA was 5.5 log copies/mL. Cumulative incidences of rashes at 0.5, 1, 2, 3 and 6 months after ART were 3.7%, 6.2%, 8.1%, 8.5% and 8.5%, respectively. By Kaplan-Meier analysis, the higher baseline CD4 cell counts had a higher probability of NVP-associated rashes (log-rank test, P=0.041). By Cox regression analysis, higher baseline CD4 cell count was associated with a higher incidence of rashes (hazard ratio=1.244, 95% confidence interval=1.045-1.482, for every 50 cells/microL increment of baseline CD4 stratum). In conclusion, NVP-associated skin rashes that lead to NVP discontinuation are common among HIV-infected patients with baseline CD4 <250 cells/microL. Despite the low baseline in this population, the higher number of baseline CD4 cells is continuously associated with a higher risk for skin rashes.