Monitoring the toxicity of antiretroviral therapy in resource limited settings: a prospective clinical trial cohort in Thailand

Background: One of the many challenges which come together with the implementation of antiretroviral therapy (ART) in settings with limited resources is the monitoring of toxicity. This monitoring increases costs of ART and strains resources. We therefore investigated the necessity for laboratory toxicity monitoring of ART in Thailand. Design, methods and participants: A prospective Thai cohort of 417 HIV-infected patients were enrolled in randomized clinical trials investigating ART. Time-dependent occurrence of grade III/IV abnormal laboratory values as defined by the AIDS Clinical Trial Group was analysed. Results: During a median observation period of 3.7 years (2.4-4.3) 142 grade III/IV toxicities occurred in 101 (24.2%) patients. Hepatic toxicity (n = 33, 7.9%), hypercholesterolaemia (n = 57, 13.7%), hypertriglyceridaemia (n = 26, 6.2%), anaemia (n = 16, 3.8%) and low platelet counts (n = 8, 1.9%) were frequently observed. Anaemia and low platelets occurred early and during the first 2 years of ART. Hepatic toxicity was seen early and throughout the observation period. Hypertriglyceridaemia and hypercholesterolaemia occurred throughout the observation period, and increased over time. Hypercreatininaemia and hyperglycaemia occurred once after 120 and 132 weeks. ART was changed or interrupted for grade III/IV hepatic toxicity, anaemia and hyperglycaemia only. The incidence rate for grade III/IV toxicity was between 5.56 (95% CI, 6.76-18.02) for low platelet counts and 41.18 (31.77-53.39) per 1000 patient years for hypercholesterolaemia. Antiretrovirals used were zidovudine, stavudine, lamivudine, zalcitabine, didanosine, efavirenz, saquinavir, ritonavir and indinavir. Conclusions: Grade III/IV toxicity is frequently observed in Thai patients treated with ART. The simple and inexpensive monitoring of ALT and haemoglobin could prevent most serious short-term toxicity. Long-term toxicity can be addressed with a yearly monitoring of triglycerides, cholesterol, glucose and creatinine if nephrotoxic drugs are use

Clinical perspectives on human genetic screening to prevent nevirapine toxicity

Nevirapine is one of the most extensively prescribed antiretroviral drugs worldwide. However, a concern is increased risk for severe toxicity when antiretroviral-naive individuals with higher CD4 T-cell counts initiate nevirapine-containing regimens. Several genetic variants are associated with nevirapine toxicities. The authors used data from a previous study to anticipate potential consequences of genetic screening to prevent nevirapine adverse events. That study enrolled cohorts of African, Asian and European descent in 11 countries, including 276 patients who had experienced severe cutaneous and/or hepatic adverse events with nevirapine-containing regimens and 587 matched nevirapine-tolerant controls. Associations were identified with HLA-Cw*04, HLA-B*35, HLA-DRB*01 and CYP2B6 516G>T (rs3745274); however, positive predictive values for these genetic markers were low, and most nevirapine-associated adverse events occurred in patients without these markers. Unless better genetic predictors are identified, nevirapine toxicity is best avoided by continuing to follow current prescribing guidelines that are based largely on CD4 T-cell criteria

Treatment outcomes and plasma level of ritonavir-boosted lopinavir monotherapy among HIV-infected patients who had NRTI and NNRTI failure

<p>Abstract</p> <p>Background</p> <p>Different strategies of ritonavir-boosted lopinavir monotherapy have been explored; however, data regarding salvage therapy among HIV-infected patients who failed nucleoside reverse transcriptase inhibitor (NRTI) and non-nucleoside reverse transcriptase inhibitor (NNRTI) is still limited.</p> <p>Methods</p> <p>A prospective study was conducted among HIV-infected patients who failed NNRTI-based antiretroviral therapy with M184V, TAMs, and NNRTI mutations, and were naïve to protease inhibitor. LPV/r at 400/100 mg and lamivudine 150 mg were given twice daily. CD4 and HIV-1 RNA were monitored at week 0, 12, 24, and 48. LPV Cmin was assayed for the first 14 patients using HPLC.</p> <p>Results</p> <p>There were 40 patients with a mean age of 37 years and 70% were male. Median (IQR) baseline CD4 was 123 (37-245) cells/mm³and median (IQR) HIV-1 RNA was 55,800 (9,670-100,000) copies/mL. By intend-to-treat analysis, 30 (75%) and 24 (60%) patients achieved HIV-1 RNA at <400 and <50 copies/mL, respectively. In as-treated analysis, the corresponding rates were 29 (83%) and 23 (67%), respectively. Low-level viral rebound was found in 6 (15%) patients at week 48. Medians CD4 at week 12, 24, 36 and 48 were 249, 283, 307, and 351 cells/mm³and significantly changed from baseline (all, <it>P </it>< 0.05). At 6 and 12 weeks, median (min-max) LPV Cmin was 6.52 (1.62-11.64) mg/L and 5.79 (0.75-16.31) mg/L, respectively. There were increments of mean total cholesterol and triglyceride at 48 weeks from baseline (<it>P </it>< 0.05).</p> <p>Conclusion</p> <p>LPV/r monotherapy with recycled lamivudine can maintain virological suppression in a substantial proportion of patients failing NNRTI-based regimen and provides adequate plasma concentrations of LPV although the incidence of low-level viremia is relatively high.</p

Development of HIV with Drug Resistance after CD4 Cell Count—Guided Structured Treatment Interruptions in Patients Treated with Highly Active Antiretroviral Therapy after Dual—Nucleoside Analogue Treatment

Background. For patients with human immunodeficiency virus (HIV) infection, structured treatment interruption (STI) is an attractive alternative strategy to continuous treatment, particularly in resource-restrained settings, because it reduces both side effects and costs. One major concern, however, is the development of resistance to antiretroviral drugs that can occur during multiple cycles of starting and stopping therapy. Methods. HIV genotypic drug resistance was investigated in 20 HIV-infected Thai patients treated with highly active antiretroviral therapy (HAART) and CD4 cell count—guided STI after dual nucleoside reverse-transcriptase inhibitor (NRTI) treatment. Resistance was tested at the time of the switch from dual-NRTI treatment to HAART and when HAART was stopped during the last interruption. Results. After STI, one major drug-resistance mutation occurred (T215Y), and, in the 4 samples with preexisting major mutations (D67N [n = 2], K70R [n = 2], T215Y [n = 2], and T215I [n = 1]), the mutations disappeared. All mutations in the HIV protease gene were minor mutations already present, in most cases, before STI was started, and their frequency was not increased through STI, whereas the frequency of reverse-transcriptase gene mutations significantly decreased after the interruptions. After the 48-week study period, no patients had virological failure. Long-term follow-up (108 weeks) showed 1 case of virological failure in the STI arm and 1 in the continuous arm. No virological failure was seen in patients with major mutations. Conclusions. Major HIV drug-resistance mutations were not induced through CD4 cell count—guided treatment interruptions in HIV-infected patients successfully treated with HAART after dual-NRTI therap

No change in calculated creatinine clearance after tenofovir initiation among Thai patients

Objectives Thai patients have a lower average body weight than patients from western Europe or the USA. Tenofovir is largely prescribed at the standard dosage of 300 mg once daily: therefore, the per kilogram dose is higher in Thailand than in the USA. We asked the question whether this higher per kilogram dose was associated with more nephrotoxicity. Methods Thai patients from the Staccato trial were treated with tenofovir/lamivudine combined with ritonavir-boosted saquinavir. Creatinine values were measured before the start of tenofovir and then every 12 weeks. Renal function was assessed using the Cockcroft-Gault formula and the MDRD formula. To compare CLCR before and after tenofovir, the t-paired or Wilcoxon signed rank tests were used. One-way analysis of variance and Spearman's correlation coefficient were used to study CLCR longitudinally. Results CLCR remained stable after a median of 21 weeks on tenofovir (difference of +1.06 mL/min; 95% CI −2.7-4.8, P = 0.58), even among patients with underlying diseases. The mean CLCR remained stable across time (P = 0.17). Conclusions We did not find renal dysfunction on tenofovir among Thai patients included in the Staccato trial. Tenofovir could be safely prescribed at a standard dosage of 300 mg once daily in the Thai populatio

Pharmacokinetic study of saquinavir hard gel caps/ritonavir in HIV-1-infected patients: 1600/100 mg once-daily compared with 2000/100 mg once-daily and 1000/100 mg twice-daily

Objectives: A pharmacokinetic comparison of three dosing regimens of saquinavir/ritonavir was carried out: 1600/100 mg once-daily with 1000/100 mg twice-daily, and 1600/100 mg once-daily with 2000/100 mg once-daily. Methods: Twenty patients on saquinavir hard gel caps/ritonavir 1600/100 mg once-daily in combination with two nucleoside reverse transcriptase inhibitors for at least 4 weeks were enrolled and randomized to either saquinavir hard gel caps/ritonavir 1000/100 mg twice-daily or 2000/100 mg once-daily. Two pharmacokinetic curves were plotted, at baseline (day 0) and 7 days after the switch. Plasma concentrations were measured at 0, 2, 4, 6, 8, 10, 12 (and 24 for once-daily dosing) hours after drug intake by validated high-performance liquid chromatographic assay (HPLC). The area under the plasma concentration-time curve (AUC0-24 or AUC0-12), maximum and minimum concentration (Cmax and Cmin) and elimination half-life were calculated using a non-compartmental model. Results: Compared with saquinavir/ritonavir 1600/100 mg once-daily dosing, the saquinavir AUC and Cmin improved significantly when dosed as 1000/100 mg twice-daily (53% and 299%, respectively), and as 2000/100 mg once-daily (71% and 65%, respectively). Low Cmin in three subjects at baseline was corrected after switch to the other dosages. Saquinavir/ritonavir 2000/100 mg once-daily was also associated with a significant increase in saquinavir Cmax (52%) compared with saquinavir/ritonavir 1600/100 mg once-daily. Conclusions: Saquinavir/ritonavir when dosed as 2000/100 mg once-daily or 1000/100 mg twice-daily achieves higher saquinavir plasma levels compared with saquinavir/ritonavir 1600/100 mg once-daily. Taking the convenience of once-daily dosing into consideration, dosage of 2000/100 mg once-daily may be preferre

Changes in metabolic toxicity after switching from stavudine/didanosine to tenofovir/lamivudine—a Staccato trial substudy

Objectives Stavudine is widely used in Thailand and is associated with mitochondrial toxicity. Here, we evaluated the effect of switching from stavudine/didanosine to tenofovir/lamivudine on measures of metabolic and mitochondrial toxicity in Thai patients. Methods Thirty-five Thai patients with full HIV RNA suppression were switched from stavudine/didanosine to tenofovir/lamivudine while receiving saquinavir/ritonavir 1600/100 mg once daily. Patients were assessed at the time of switch and 24 and 48 weeks after for lipids, liver enzymes, lactate, mitochondrial DNA content and limb/total fat mass by dual energy X-ray absorptiometry (DEXA) scanning. Results Forty-eight weeks after the switch, there were significant reductions in lipids and lactate, but no change in liver enzymes. There was reversal of lipoatrophy, as shown by rises in limb fat mass (+0.38 kg, P = 0.006) and total fat mass (+0.69 kg, P = 0.02) on DEXA scan. Patients perceived weight improvement, but did not report reversal of lipoatrophy of individual body parts. The mitochondrial DNA/nuclear DNA ratio rose (+1.06, P < 0.0001). Conclusions After the nucleoside reverse transcriptase inhibitor switch, reversal of mitochondrial toxicity was consistent with switch studies of mainly Caucasian patients, although the peripheral mononuclear cell mitochondrial DNA rise exceeded previous report

A Prospective, Randomized Trial of Structured Treatment Interruption for Patients with Chronic HIV Type 1 Infection

Background. Structured treatment interruption was evaluated in 74 patients who had been pretreated with antiretrovirals, consisting of 2 nucleoside reverse-transcriptase inhibitors (NRTIs) for 1 year followed by 3 years of highly active antiretroviral therapy containing a protease inhibitor. Methods. Patients with a CD4 cell count of ⩾350 cells/µL and a plasma viral load of <50 copies/mL were randomized to 3 therapy arms: (1) continuous therapy, (2) CD4 cell count—guided theory, and (3) week-on/week-off (WOWO) therapy. The efficacy and safety of structured treatment interruption and antiretroviral use were evaluated in human immunodeficiency type 1 (HIV-1)—infected patients. The study end points were percentage of patients who developed AIDS or who died and a CD4 cell count of ⩾350 cells/µL. Intergroup differences were analyzed using analysis of variance and Kruskal-Wallis tests. Results. Baseline characteristics at the start of the structured treatment interruption were similar. At week 48, no patient had died, and 1 patient in the WOWO group had an AIDS-defining condition. The proportions of patients with a CD4 cell count of ⩾350 cells/µL were 100%, 87%, and 96% in treatment arms 1, 2, and 3, respectively. The percentages of weeks of antiretroviral use were 100%, 41.1%, and 69.8% in arms 1, 2, and 3, respectively. The adverse events were not significantly different among arms (P = .27). Thirty-one percent of patients in the WOWO group experienced virological failure. Conclusion. WOWO therapy maintained a CD4 cell count of ⩾350 cells/µL in almost all patients but was associated with high virological failures rates (possibly resulting from previous dual-NRTI therapy), indicating that this strategy is less useful. Receipt of CD4 cell count—guided therapy resulted in comparable clinical outcomes to continuous therapy and may save antiretroviral-associated costs, but this needs to be confirmed by a larger tria