Chureeratana Bowonwatanuwong

Efavirenz pharmacokinetics during the third trimester of pregnancy and postpartum.

Background: The impact of pregnancy on efavirenz (EFV) pharmacokinetics is unknown. Methods: International Maternal Pediatric Adolescent AIDS Clinical Trials P1026s is an on-going, prospective, nonblinded study of antiretroviral pharmacokinetics in HIV-infected pregnant women that included a cohort receiving 600 mg EFV once daily as part of combination antiretroviral therapy. Intensive steady-state 24-hour blood sampling was performed during the third trimester and at 6–12 weeks postpartum. Maternal and umbilical cord blood samples were drawn at delivery. Pharmacokinetics targets were the estimated 10th percentile EFV area under the curve (AUC) in nonpregnant historical controls (40.0 mcg·hr−1·mL−1) and a trough concentration of 1 mcg/mL. Results: Twenty-five women were enrolled during the third trimester: median (range) age was 29.3 (18.9–42.9) years, weight 69.0 (40–130) kg, and gestational age 32.9 (30.1–38.7) weeks. Median (range) EFV AUC0–24, Cmax, and C24 hours were 55.4 mcg·hr−1·mL−1 (13.5-220.3), 5.4 mcg/mL (1.9–12.2), and 1.6 mcg/mL (0.23–8.13), respectively. EFV AUC and Cmax did not differ during pregnancy and postpartum but C24 hours was lower during the third trimester (1.6 vs. 2.1 mcg/mL, P = 0.01). During the third trimester, 5 of 25 (20%) women had an EFV AUC below the target and 3 of 25 (12%) had a trough concentration below 1 mcg/mL. EFV cord blood/maternal concentration ratio was 0.49 (0.37–0.74). All women had a HIV-1 RNA viral load less than 400 copies per milliliter at delivery and 19 (76%) had a viral load below 50 copies per milliliter. One child was perinatally HIV infected. Three women were exposed to EFV throughout the first 6 weeks of pregnancy. EFV was well tolerated, and among the 25 infants, no congenital anomalies or newborn complications were reported. Conclusions: Changes in EFV pharmacokinetics during pregnancy compared with postpartum are not sufficiently large enough to warrant a dose adjustment during pregnancy.

A randomized comparison of second-line lopinavir/ritonavir monotherapy versus tenofovir/lamivudine/lopinavir/ritonavir in patients failing NNRTI regimens: the HIV STAR study.

BACKGROUND Data informing the use of boosted protease inhibitor (PI) monotherapy as second-line treatment are limited. There are also no randomized trials addressing treatment options after failing first-line non-nucleoside reverse transcriptase inhibitor (NNRTI)-regimens. METHODS HIV-infected subjects ≥18 years, with HIV RNA≥1,000 copies/ml while using NNRTI plus 2 NRTIs, and naive to PIs were randomized to lopinavir/ritonavir (LPV/r) 400/100 mg twice daily monotherapy (mono-LPV/r) or tenofovir disoproxil fumarate (TDF) once daily plus lamivudine (3TC) twice daily plus LPV/r 400/100 mg twice daily (TDF/3TC/LPV/r) at nine sites in Thailand. The primary outcome was time-weighted area under curve (TWAUC) change in HIV RNA over 48 weeks. The a priori hypothesis was that the mono-LPV/r arm would be considered non-inferior if the upper 95% confidence limit in TWAUC mean difference was ≤0.5 log(10) copies/ml. RESULTS The intention-to-treat (ITT) population comprised 195 patients (mono-LPV/r n=98 and TDF/3TC/LPV/r n=97): male 58%, baseline mean (sd) age of 38 (7) years, CD4(+) T-cell count of 204 (135) cells/mm(3) and HIV RNA of 4.1 (0.6) log(10) copies/ml. The majority had HIV-1 recombinant CRF01_AE infection, and thymidine analogue mutation (TAM)-2 was 3× more common than TAM-1. At 48 weeks, the difference in TWAUC HIV RNA between arms was 0.15 (95% CI -0.04, 0.33) log(10) copies/ml, consistent with our definition of non-inferiority. However, the proportion with HIV RNA<50 copies/ml was significantly lower in the mono-LPV/r arm: 61% versus 83% (ITT, P<0.01). Baseline HIV RNA≥5 log(10) copies/ml (P<0.001) and mono-LPV/r use (P=0.003) were predictors of virological failure. Baseline genotypic sensitivity scores ≥2 and TAM-2 were associated with better virological control in subjects treated with the TDF-containing regimen. CONCLUSIONS In PI-naive patients failing NNRTI-based first-line HAART, mono-LPV/r had a significantly lower proportion of patients with HIV RNA<50 copies/ml compared to the TDF/3TC/LPV/r treatment. Thus, mono-LPV/r should not be recommended as a second-line option.

Incidence and Risk Factors for Tenofovir-Associated Renal Function Decline Among Thai HIV-Infected Patients with Low-Body Weight

OBJECTIVES we aimed at determining the incidence and factors for TDF-associated renal function decline among Thai HIV-infected patients. METHODS retrospective and prospective cohort studies were conducted. We enrolled HIV-infected adults who had initiated TDF. Renal function decline that was defined by a decrease of 25% in glomerular filtration rate (GFR) from the baseline. Factors associated with the renal function decline were determined. RESULTS a total of 405 patients with a median (IQR) body weight of 56.5 (50.5-65.0) kg were enrolled. All but four (99%) were antiretroviral treatment-experience patients. A median (IQR) duration of receiving TDF was 16 (8-21) months. Of these, 78 (19.3%) patients had a 25% decrease in GFR with the incidence rate of 16.2 per 100 person-years. By Kaplan-Meier survival analysis, median time to a 25% decrease in GFR was 28 [95% confidence interval (CI) 25.2-30.8] months. By multiple logistic regression, lower body weight [odds ratio (OR) 1.15 per 5 kg, 95% CI 1.00-1.33], lower body mass index (BMI) (OR 2.26 per 1 kg/m(2), 95% CI 1.74-2.94), baseline GFR (OR 1.62 per 10 ml/min/1.73m(2), 95% CI 1.39-1.88), protease inhibitor (OR 2.12, 95% CI 1.15-3.92), and nephrotoxic drug (OR 3.16, 95% CI 1.44-6.98) were statistically significant factors associated with a 25% decrease in GFR. CONCLUSIONS the study revealed high incidence of TDF-associated renal function decline among patients with low-body weight and BMI. Additional risk factors were baseline GFR, receiving protease inhibitor, and nephrotoxic drugs. Close monitoring of renal function is warranted among patients with these risk factors.

High rate multiple drug resistances in HIV-infected patients failing nonnucleoside reverse transcriptase inhibitor regimens in Thailand, where subtype A/E is predominant.

The prevalence of drug resistance was determined among 64 HIV-infected Thai patients who were failed while receiving nonnucleoside reverse transcriptase inhibitor (NNRTI)–based regimens. Eighty-nine percent of patients had 1 or more NNRTI mutation resistances. Almost all patients had resistance to at least 1 nucleoside reverse transcriptase inhibitor (NRTI), and 42% had multiple-NRTI resistance.

Low-dose versus standard-dose ritonavir-boosted atazanavir in virologically suppressed Thai adults with HIV (LASA): a randomised, open-label, non-inferiority trial

BACKGROUND Thai patients with HIV have higher exposure to HIV protease inhibitors than do white people and dose reduction might be possible. We compared the efficacy of low-dose with standard-dose ritonavir-boosted atazanavir in virologically suppressed Thai patients with HIV. METHODS In this randomised, open-label, non-inferiority trial, we recruited patients aged 18 years or older who were receiving ritonavir-boosted protease-inhibitor-based antiretroviral therapy (ART) with HIV plasma viral loads of less than 50 copies per mL, an alanine aminotransferase concentration of less than 200 IU/L, and a creatinine clearance of at least 60 mL/min from 14 hospitals in Thailand. We excluded patients who had active AIDS-defining disease or opportunistic infections, had a history of an HIV viral load of 1000 copies per mL or more after 24 weeks of any ritonavir-boosted protease-inhibitor-based ART, used concomitant medications that could interact with the study drugs, were pregnant or lactating, had illnesses that might change the effect of the study drugs, or had a history of sensitivity to the study drugs. A biostatistician at the study coordinating centre randomly allocated patients (1:1) to switch the protease inhibitor for oral atazanavir 200 mg and ritonavir 100 mg or for atazanavir 300 mg and ritonavir 100 mg once daily, both with two nucleoside or nucleotide reverse transcriptase inhibitors at recommended doses. Randomisation was done with a minimisation schedule, stratified by recruiting centre, use of tenofovir, and use of indinavir as a component of the preswitch regimen. The primary endpoint was the proportion of patients with viral loads of less than 200 copies per mL at week 48, and we followed up patients every 12 weeks. Treatments were open label, the non-inferiority margin was -10%, and all patients who received at least one dose of study medication were analysed. This trial is registered with ClinicalTrials.gov, number NCT01159223. FINDINGS Between July 6, 2011, and Dec 23, 2013, we randomly assigned 559 patients: 279 to receive atazanavir 200 mg and ritonavir 100 mg (low dose) and 280 to atazanavir 300 mg and ritonavir 100 mg (standard dose). At week 48, 265 (97·1%) of 273 in the low-dose group and 267 (96·4%) of 277 in the standard-dose group had viral loads of less than 200 copies per mL (difference 0·68; 95% CI -2·29 to 3·65). Seven (3%) of 273 in the low-dose group and 21 (8%) of 277 in the standard-dose group discontinued their assigned treatment (p=0·01). 46 (17%) of 273 participants in the low-dose group and 97 (35%) of 277 in the standard-dose group had total bilirubin grade 3 or higher toxicity (≥3·12 mg/dL; p<0·0001). INTERPRETATION A switch to low-dose atazanavir should be recommended for Thai patients with well controlled HIV viraemia while on regimens based on boosted protease inhibitors. FUNDING The National Health Security Office and Kirby Institute for Infection and Immunity in Society.

New-Onset Diabetes and Antiretroviral Treatments in HIV-Infected Adults in Thailand.

Background:Use of several antiretrovirals (ARVs) has been shown to be associated with a higher risk of diabetes in HIV-infected adults. We estimated the incidence of new-onset diabetes and assessed the association between individual ARVs and ARV combinations, and diabetes in a large cohort in Thailand. Methods:We selected all HIV-1–infected, nondiabetic, antiretroviral-naive adults enrolled in the Program for HIV Prevention and Treatment cohort (NCT00433030) between January 2000 and December 2011. Diabetes was defined as confirmed fasting plasma glucose ≥126 mg/dL or random plasma glucose ≥200 mg/dL. Incidence was the number of cases divided by the total number of person-years of follow-up. Association between ARVs and ARV combinations, and new-onset diabetes was assessed using Cox proportional hazards models. Results:Overall, 1594 HIV-infected patients (76% female) were included. Median age at antiretroviral therapy initiation was 32.5 years. The incidence rate of diabetes was 5.0 per 1000 person-years of follow-up (95% confidence interval: 3.8 to 6.6) (53 cases). In analyses adjusted for potential confounders, exposure to stavudine + didanosine [adjusted hazard ratio (aHR) = 3.9; P = 0.001] and cumulative exposure ≥1 year to zidovudine (aHR = 2.3 vs. no exposure; P = 0.009) were associated with a higher risk of diabetes. Conversely, cumulative exposure ≥1 year to tenofovir (aHR = 0.4 vs. no exposure; P = 0.02) and emtricitabine (aHR = 0.4 vs. no exposure; P = 0.03) were associated with a lower risk. Conclusions:The incidence of diabetes in this predominantly female, young, lean population was relatively low. Although stavudine and didanosine have now been phased out in most antiretroviral therapy programs, our analysis suggests a higher risk of diabetes with zidovudine, frequently prescribed today in resource-limited settings.

Monitoring of Renal Function among HIV-Infected Patients Receiving Tenofovir in a Resource-Limited Setting :

The use of tenofovir disoproxil fumarate (TDF) is supposed to be increased in a resource-limited setting due to the changing of the guidelines. TDF–associated renal function declines among HIV-infected patients were defined by an increase of serum creatinine (SCr) >1.5 times, a 25% decrease in calculated creatinine clearance (CCrCl), or an estimated glomerular filtration rate (eGFR) from the baseline. Of all, 99% were antiretroviral treatment (ART)-experienced patients. At the 30th month, 19 (5.3%), 53 (14.9%), and 63 (17.7%) patients had renal function decline as defined by the above criteria with an incidence of 4.5, 12.5, and 14.6/100 person-year. A proportion of patients with a renal function decline detected by CCrCl or eGFR criteria was not different (P = .301), whereas, it differed from that detected by SCr criteria (P < .001). In conclusion, we encourage either CCrCl or eGFR calculations in monitoring renal function decline among HIV-infected patients receiving TDF in resource-limited settings.

Plasma and Intracellular Pharmacokinetics of Tenofovir Disoproxil Fumarate 300 mg Every 48 Hours vs 150 mg Once Daily in HIV-Infected Adults With Moderate Renal Function Impairment

BACKGROUND The approved tenofovir disoproxil fumarate (TDF) dose of 300 mg every 48 hours for adults with moderate renal impairment is often confusing and inconvenient. Using a new TDF formulation, we compared the pharmacokinetics of the standard dose with a dose of 150 mg once daily in HIV-infected adults. METHODS This was an open-label pharmacokinetic study. Virologically suppressed HIV-infected adults with a creatinine clearance 30 to <50 mL/minute receiving TDF 300 mg every 48 hours as part of a nonnucleoside reverse transcriptase inhibitor (NNRTI)- or lopinavir/ritonavir (LPV/r)-based regimen were enrolled. Intensive 48-hour blood sampling for pharmacokinetic assessment was performed at enrollment, after which the TDF dose was changed to 150 mg once daily. Two weeks later, 24-hour blood sampling was performed; subjects then returned to the standard dose. Tenofovir (TFV) pharmacokinetic parameters were calculated using a noncompartmental analysis. RESULTS Forty adults (55% female) were enrolled: 20 receiving NNRTI-based and 20 receiving LPV/r-based treatment. Median age was 56 years (range, 44-65 years), weight 51 kg (range, 38-80 kg), and creatinine clearance 43.9 mL/minute (range, 30.9-49.7 mL/minute). The TFV geometric mean ratio of the area under the curve (AUC0-48 h) for every 24 hours vs every 48 hours was 1.09 (90% confidence interval [CI], .98-1.22) and 1.00 (90% CI, .92-1.09) for patients receiving NNRTI- and LPV/r-based treatment, respectively. Concomitant LPV/r use markedly increased TFV plasma concentrations, and AUC0-48 h was 67% higher with the standard dose, whereas no differences in intracellular TFV diphosphate concentrations were observed. All subjects remained virologically suppressed, and no drug-related adverse events were reported. CONCLUSIONS TDF 150 mg every 24 hours provides comparable systemic exposure to the standard dose of 300 mg every 48 hours in patients with moderate renal impairment. CLINICAL TRIALS REGISTRATION NCT01671982.

Influence of body weight on achieving indinavir concentrations within its therapeutic window in HIV-infected Thai patients receiving indinavir boosted with ritonavir

Indinavir boosted with ritonavir (IDV/r) dosing with 400/100 mg, twice daily, is preferred in Thai adults, but this dose can lead to concentrations close to the boundaries of its therapeutic window. The objectives of this analysis were to validate a population pharmacokinetic model to describe IDV/r concentrations in HIV-infected Thai patients and to investigate the impact of patient characteristics on achieving adequate IDV concentrations. IDV/r concentration data from 513 plasma samples were available. Population means and variances of pharmacokinetic parameters were estimated using a nonlinear mixed effects regression model (NONMEM Version VI). Monte Carlo simulations were performed to estimate the probability of achieving IDV concentrations within its therapeutic window. IDV/r pharmacokinetics were best described by a one-compartment model coupled with a single transit compartment absorption model. Body weight influenced indinavir apparent oral clearance and volume of distribution and allometric scaling significantly reduced the interindividual variability. Final population estimates (interindividual variability in percentage) of indinavir apparent oral clearance and volume of distribution were 21.3 L/h/70 kg (30%) and 90.7 L/70 kg (22%), respectively. Based on model simulations, the probability of achieving an IDV trough concentration greater than 0.1 mg/L was greater than 99% for 600/100 mg and greater than 98% for 400/100 mg, twice daily, in patients weighing 40 to 80 kg. However, the probability of achieving IDV concentrations associated with an increased risk of drug toxicity (greater than 10.0 mg/L) increased from 1% to 10% with 600/100 mg compared with less than 1% with 400/100 mg when body weight decreased from 80 to 40 kg. The validated model developed predicts that 400/100 mg of IDV/r, twice daily, provides indinavir concentrations within the recommended therapeutic window for the majority of patients. The risk of toxic drug concentrations increases rapidly with IDV/r dose of 600/100 mg for patients less than 50 kg and therapeutic drug monitoring of IDV concentrations would help to reduce the risk of IDV-induced nephrotoxicity.