Comparative efficacy of nucleoside/nucleotide reverse transcriptase inhibitors in combination with efavirenz: results of a systematic overview

Patterns of acquired HIV-1 drug resistance mutations and predictors of virological failure in Moshi, Northern Tanzania

Emergence of HIV drug resistance poses a serious risk of inactivity to all currently approved antiretroviral drugs. Profiles of HIV drug resistance mutations (HIVDRM) and virological failure (VF) are not extensively studied in Tanzania. This study aimed to determine HIVDRM and predictors of VF in HIV-infected individuals failing first-line HIV drugs in Moshi, Northern Tanzania. A case-control study was conducted at Kilimanjaro Christian Medical Centre, Mawenzi, Pasua and Majengo health facilities with HIV-care and treatment clinics from October, 2017 to August, 2018. Cases and controls were HIV-infected individuals with VF and viral suppression (VS) respectively. HIV-1 reverse transcriptase and protease genes were amplified and sequenced. Stanford University's HIV drug resistance database and REGA subtyping tool 3.0 determined HIVDRM and HIV-1 subtypes respectively. Odds ratios (OR) with 95% confidence interval (95% CI) investigated predictors of VF. P-value < 5% was considered statistically significant. A total of 124 participants were recruited, of whom 63 (50.8%) had VF, 61 (49.2%) had VS and 82 (66.1%) were females. Median [IQR] age and duration on ART were 45 [35-52] years and 72 [48-104] months respectively. Twenty-five out of 26 selected samples from cases were successfully sequenced. Twenty-four samples (96%) had at least one major mutation conferring resistance to HIV drugs, with non-nucleoside analogue reverse transcriptase inhibitor (NNRTI)-resistance associated mutations as the majority (92%). Frequent NNRTI-resistance associated mutations were K103N (n = 11), V106M (n = 5) and G190A (n = 5). Prevalent nucleoside analogue reverse transcriptase inhibitors-resistance associated mutations were M184V (n = 17), K70R (n = 7) and D67N (n = 6). Dual-class resistance was observed in 16 (64%) samples. Thirteen samples (52%) had at least one thymidine analogue-resistance associated mutation (TAM). Three samples (12%) had T69D mutation with at least 1 TAM. Two samples (8%) had at least one mutation associated with protease inhibitor resistance. Age [aOR = 0.94, 95% CI (0.90-0.97), p < 0.001] and occupation [aOR = 0.35, 95% CI (0.12-1.04), p = 0.059] associated with VF. In conclusion, HIV drug resistance is common among people failing antiretroviral therapy. Resistance testing will help to guide switching of HIV drugs.

Long Term Exposure to Tenofovir Disoproxil Fumarate-Containing Antiretroviral Therapy Is Associated with Renal Impairment in an African Cohort of HIV-Infected Adults

OBJECTIVES AND METHOD

There are growing concerns of tenofovir disoproxil fumarate (TDF)-associated renal toxicity. We evaluated the effect of long-term TDF exposure on renal function in a cohort of HIV-1-infected Nigerians between 2006 and 2015. Multivariate logistic regression was used to identify predictors of renal impairment at different time over 144 weeks of antiretroviral therapy (ART).

RESULTS

Data of 4897 patients, median age 42 years (interquartile range: 36-49), and 61% females were analyzed. The prevalence of renal impairment increased from 10% at week 24 to 45% at 144 weeks in TDF-exposed participants compared to an increase from 8% at 24 weeks to 14% at 144 weeks in TDF-unexposed participants. Tenofovir disoproxil fumarate exposure predicted the risk of renal impairment at 144 weeks of ART (odds ratio: 2.36; 95% confidence interval: 1.28-4.34).

CONCLUSION

Long-term exposure to TDF-based ART significantly increases the likelihood of renal impairment. The continued use of TDF-based regimen in our setting should be reviewed. We recommend the urgent introduction of tenofovir alafenamide-based regimen in the HIV treatment guidelines of Nigeria and other resource-limited countries.

Antiretroviral Therapy-associated Adverse Drug Reactions and their Effects on Virologic Failure- A Retrospective Cohort Study in Nigeria

Background:

Adverse drug reactions (ADRs) associated with antiretroviral therapy (ART) can rapidly reverse the gains of ART resulting in poor health outcomes. We need an improved under-standing of specific ART-related ADRs that influence virologic outcomes.

Objective:

To investigate the frequency of clinical ADRs and assess their effect on virologic failure in patients on ART.

Method:

We described the prevalence of major clinical ADRs, and the association between specific ADRs and virologic failure in a clinic cohort of HIV-1 infected Nigerians aged ≥18 years, on first-line ART between June 2004 and February 2012. Multivariable logistic regression was run to identify predictors of virologic failure at 24 and 72 weeks of ART.

Results:

Data of 12,115 patients with a median age of 34 (interquartile range: 29-41) years, and pre-dominantly females (67%) were evaluated. Overall, 957 (7.9%) patients experienced at least one ADR during a median follow-up period of 4 years (interquartile range: 1-7). The three most prevalent ADRs were lipodystrophy (2.6%), anemia (1.9%), and skin rash (0.7%). Virologic failure rate was 36% and 34% at 24 and 72 weeks of ART, respectively. Anemia independently predicted the odds of virologic failure at 72 weeks of ART (adjusted odds ratio, 1.74; 95% CI: 1.2-2.51); adjusted for sex, age, pre-treatment CD4+ cell count, antiretroviral regimen, and medication refill adherence.

Conclusion:

Antiretroviral therapy-associated anemia increases the likelihood of late virologic failure. We recommend routine monitoring of hemoglobin levels and prompt management of anemia in all pa-tients on ART as a strategy to improve virologic success rates.

Adverse drug reaction monitoring in patients on antiretroviral therapy in a tertiary care hospital in Eastern India

BACKGROUND

Besides unparalleled benefits, highly active antiretroviral therapy is also associated with wide range of potential adverse drug reactions (ADRs), which hinders treatment adherence. The present study was thus designed to monitor and explore the pattern of occurrence of ADRs to various antiretroviral therapy (ART) regimens in a tertiary care ART setup.

MATERIALS AND METHODS

A prospective, observational clinical study was carried out in the outpatient setting of nodal ART center of Eastern India. A total of 610 patients on various ART regimens were studied for suspected ADRs over 12 months. Adverse event history, medication history, and other relevant details were captured. Causality and severity of each reported ADR were duly assessed.

RESULTS

32.45% patients of total study participants presented with a total of 330 ADRs. Patients from zidovudine-based regimens presented with majority of ADRs such as anemia (up to 36%), central nervous system (CNS), and gastrointestinal (GI) side effects. Tenofovir-based regimens were, however, found to be mildly safer. The combination with Efavirenz was associated with majorly CNS side effects while that of nevirapine was associated with rash and pigmentation of nails. Atazanavir boosted second-line regimens were notably associated with increased serum lipid levels followed by other GI and CNS adverse effects. Increased liver enzymes were found in atazanavir-based second-line ART.

CONCLUSION

The study enables to obtain information on the incidence and pattern of ADRs associated with various antiretroviral regimens, thereby reducing its occurrence and protecting the patient population from avoidable harm. Need of intensive monitoring for ADRs in ARTs thus seems to be a mandate.

Efficacy and safety of a once-daily single-tablet regimen of tenofovir, lamivudine, and efavirenz assessed at 144 weeks among antiretroviral-naïve and experienced HIV-1-infected Thai adults

OBJECTIVE

To assess the efficacy and safety of a new single-tablet regimen (STR) of tenofovir disoproxil fumarate (TDF) 300mg, lamivudine (3TC) 300mg, and efavirenz (EFV) 600mg in HIV-infected Thai patients.

METHODS

This was a prospective study performed for 144 weeks among 51 treatment-naïve patients and 49 experienced patients on separate tablets of TDF, 3TC, and EFV with HIV RNA<50 copies/ml. CD4, HIV RNA, liver and renal function, and lipid profiles were assessed at baseline, weeks 12, 24, and 48, and then every 24 weeks.

RESULTS

The median baseline CD4 cell count was 512 cells/μl for treatment-experienced patients and 230 cells/μl for treatment-naïve patients. Median baseline log₁₀ HIV-1 RNA for treatment-naïve subjects was 4.9 copies/ml. From the intention-to-treat (ITT) analysis, the proportion of subjects with HIV RNA <50 copies/ml at week 48, 96, and 144 was 95%, 94%, and 94%, respectively, for antiretroviral-experienced patients and 88%, 90%, and 80%, respectively, for antiretroviral-naïve patients. One virological failure at week 12 had primary drug resistance of K70R, T69D, V75L. Three serious adverse events occurred (tension headache, infective endocarditis, and cervical dysplasia) and another three discontinued the study drug due to EFV intolerance.

CONCLUSIONS

This generic STR TDF/3TC/EFV is effective and well-tolerated. These findings lend support to the use of this generic STR as first-line antiretroviral therapy in resource-limited settings.

Incidence and predictors of adverse drug events in an African cohort of HIV-infected adults treated with efavirenz

INTRODUCTION

Adverse drug reactions associated with efavirenz (EFV) therapy are poorly described beyond the first year of treatment. We aimed to describe the incidence and predictors of EFV-related adverse drug reactions (ADRs) in a cohort of adult Nigerian HIV-infected patients on antiretroviral therapy (ART).

METHODS

This retrospective cohort study utilized clinical data of HIV-1 infected adults (aged ≥15 years), commenced on efavirenz containing-regimen between January 2004 and December 2011. The time-dependent occurrence of clinical adverse events as defined by the World Health Organization was analyzed by Cox regression analysis.

RESULTS

A total of 2920 patients with baseline median (IQR) age of 39 (33-46) years, largely made up of men (78%) were included in the study. During 8834 person-years of follow up, 358 adverse drug events were reported; the incidence rate was 40.3 ADRs per 1000 person-years of treatment. Lipodystrophy and neuropsychiatric disorders were the most common ADRs with incidences of 63 and 30 per 1000 patients respectively. About one-third of the neuropsychiatric adverse events were within 12 months of commencement of ART. The risk of neuropsychiatric ADRs was independently predicted for women [adjusted hazard ratio (aHR) 9.05; 95% CI: 5.18-15.82], those aged <40 years (aHR 2.59; 95% CI: 1.50-4.45), advanced HIV disease (WHO stage 3 or 4) [aHR 2.26; 95% CI: 1.37-3.72], and zidovudine [aHR 2.21; 95% CI: 1.27-3.83] or stavudine [aHR 4.22; 95% CI: 1.99-8.92] containing regimen compared to tenofovir.

CONCLUSION

Neuropsychiatric adverse drug events associated with efavirenz-based ART had both early and late onset in our clinical cohort of patients on chronic EFV therapy. Continuous neuropsychiatric assessment for improved detection and management of neuropsychiatric ADRs is recommended in resource-limited settings where the use of efavirenz-based regimens has been scaled up.

Efavirenz-Based Regimens in Antiretroviral-Naive HIV-Infected Patients: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Efavirenz, a non-nucleoside reverse-transcriptase inhibitor (NNRTI) is one of the most commonly prescribed antiretroviral drugs. The present article provides a systematic overview and meta-analysis of clinical trials comparing efavirenz and other active drugs currently recommended for treatment of HIV-infected, antiretroviral-naive patients. Electronic databases (Pubmed, Embase, the Cochrane Library, Trip Database) were searched up till 23 December 2013 for randomized controlled clinical trials published as a peer-reviewed papers, and concerning efavirenz-based regimens used as initial treatment for HIV infection. Thirty-four studies were included in the systematic review, while twenty-six trials were suitable for the meta-analysis. Efavirenz was compared with drugs from four different classes: NNRTIs other than efavirenz (nevirapine or rilpivirine), integrase strand transfer inhibitors (InSTIs), ritonavir-boosted protease inhibitors (bPI) and chemokine (C-C motif) receptor 5 (CCR5) antagonists (maraviroc), all of them were added to the background regimen. Results of the current meta-analysis showed that efavirenz-based regimens were equally effective as other recommended regimens based on NNRTI, ritonavir-boosted PI or CCR5 antagonist in terms of efficacy outcomes (disease progression and/or death, plasma viral HIV RNA <50 copies/ml) while statistically significant more patients treated with InSTI achieved plasma viral load <50 copies/ml at week 48. In comparison with both InSTI-based and CCR5-based therapy, efavirenz-based treatment was associated with a higher risk of therapy discontinuation due to adverse events. However, comparisons of efevirenz-based treatment with InSTI-based and CCR5-based therapy were based on a limited number of trials, therefore, conclusions from these two comparisons must be confirmed in further reliable randomized controlled studies. Results of our meta-analysis support the present clinical guidelines for antiretroviral-naive, HIV-infected patients, in which efavirenz is one of the most preferred regimens in the analyzed population. Beneficial safety profile of InSTI-based and CCR5-based therapy over efavirenz-based treatment needs further studies.

HIV type 1 infection up-regulates TLR2 and TLR4 expression and function in vivo and in vitro

Toll-like receptors (TLRs) play a critical role in innate immunity against pathogens. Their stimulation induces the activation of NF-κB, an important inducer of HIV-1 replication. In recent years, an increasing number of studies using several cells types from HIV-infected patients indicate that TLRs play a key role in regulating the expression of proinflammatory cytokines and viral pathogenesis. In the present study, the effect of HIV-1 stimulation of monocyte-derived macrophage (MDM) and peripheral blood mononuclear cell (PBMC) subpopulations from healthy donors on the expression and functions of TLR2 and TLR4 was examined. In addition, and to complete the in vitro study, the expression pattern of TLR2 and TLR4 in 49 HIV-1-infected patients, classified according to viral load and the use of HAART, was determined and compared with 25 healthy subjects. An increase of TLR expression and production of proinflammatory cytokines were observed in MDMs and PBMCs infected with HIV-1 in vitro and in response to TLR stimulation, compared to the mock. In addition, an association between TLR expression and up-regulation of CD80 in plasmacytoid dendritic cells (pDCs) was observed. The ex vivo analysis indicated increased expression of TLR2 and TLR4 in myeloid dendritic cells (mDCs), but only of TLR2 in monocytes obtained from HIV-1-infected patients, compared to healthy subjects. Remarkably, the expression was higher in cells from patients who do not use HAART. In monocytes, there was a positive correlation between both TLRs and viral load, but not CD4(+) T cell numbers. Together, our in vitro and ex vivo results suggest that TLR expression and function can be up-regulated in response to HIV-1 infection and could affect the inflammatory response. We propose that modulation of TLRs represents a mechanism to promote HIV-1 replication or AIDS progression in HIV-1-infected patients.

Different baseline characteristics and different outcomes of HIV-infected patients receiving HAART through clinical trials compared with routine care in Mexico

BACKGROUND

The efficacy of antiretroviral therapy (ART) has been established through clinical trials (CTs). However, selection bias and differences can limit their applicability to the general population.

METHODS

All treatment-naive HIV-infected patients who began ART in routine care (RC) between 2000 and 2008 were compared with all patients who initiated ART through a CT in terms of incidence of virological failure (VF), increase in CD4(+) count, mortality rate, and loss to follow-up (LTFU).

RESULTS

At baseline, the RC group had less years of education, higher unemployment rate, higher proportion of females (14.2 vs. 5.7%; P < 0.01), lower median CD4(+) (97 vs. 158 cells/μL; P < 0.01), and lower proportion of patients with hemoglobin >12 g/dL (74 vs. 83%, P = 0.04). VF at week 48 was less frequent in the CT compared with the RC group (1.8% vs. 6.21%, P = 0.02). In multivariate analysis, participation in CT [odds ratio (OR): 0.20, 95% confidence interval (CI): 0.04 to 0.91, P = 0.03], hemoglobin >12 g/dL (OR: 0.29, 95% CI 0.09-0.89, P = 0.03), and receiving an optimal highly active antiretroviral therapy regimen (OR: 0.09, 95% CI: 0.01 to 0.52, P < 0.01) remained associated with lower risk of VF. All cause mortality was 0.017 (95% CI: 0.002 to 0.122) versus 0.094 (95% CI: 0.053 to 0.17) deaths per 1000 person-days in the CT group and in the RC group, respectively (P = 0.05). No differences were found in the proportion of patients LTFU.

CONCLUSIONS

Receiving ART through CT was associated with lower probability of VF, lower mortality (probably related to less severe clinical characteristics at baseline), and similar rates of LTFU than RC.

Cost-effectiveness of nucleoside reverse transcriptase inhibitor pairs in efavirenz-based regimens for treatment-naïve adults with HIV infection in the United States

OBJECTIVE

To estimate the cost-effectiveness of once-daily tenofovir/emtricitabine compared with twice-daily zidovudine/lamivudine and once-daily abacavir/lamivudine in treatment-naïve adults with HIV-1 infection in the United States.

METHODS

A Markov model with four therapy lines and six health states based on CD4(+) cell-count ranges was developed to estimate lifetime costs and health outcomes. Efficacy data (virologic response and CD4(+) cell-count changes) for first-line therapy were from 144-week results of Study 934 comparing tenofovir/emtricitabine with zidovudine/lamivudine and 48-week results of Study CNA30024 comparing abacavir/lamivudine with zidovudine/lamivudine, all in combination with efavirenz. Data from Study CNA30024 for abacavir/lamivudine were adjusted to allow for an indirect comparison with tenofovir/emtricitabine. Subsequent therapy lines were based on likely baskets of antiretroviral therapy recommended by US treatment guidelines. Utility values, mortality rates, and costs (2009 US dollars) were obtained from published sources. Base-case results were tested in sensitivity and variability analyses.

RESULTS

Average discounted results showed that individuals using tenofovir/emtricitabine were predicted to remain on first-line therapy for 7.7 years, accrue lifetime costs of $747,327, and experience 15.75 quality-adjusted life-years (QALYs), compared with 6.0 years, $777,090, and 15.68 QALYs for individuals using abacavir/lamivudine and 5.8 years, $778,287, and 15.44 QALYs for individuals using zidovudine/lamivudine. Tenofovir/emtricitabine was cost-effective compared with the other two first-line regimens in more than 75% of all probabilistic sensitivity analysis simulation runs for every willingness-to-pay threshold between $0 and $250,000 per QALY gained. Results were robust in variability and one-way sensitivity analyses.

CONCLUSIONS

Tenofovir/emtricitabine was predicted to be more effective and cost-saving compared with abacavir/lamivudine and zidovudine/lamivudine in treatment-naïve adults with HIV-1 infection in the United States.

An update on the use of Atripla in the treatment of HIV in the United States

Atripla^® (Gilead Sciences Inc, Foster City, CA, USA and Bristol-Myers Squibb, New York City, NY, USA) is a coformulated single pill composed of efavirenz, emtricitabine, and tenofovir disoproxil, intended as a once-daily potent combination antiretroviral therapeutic agent. Its efficacy is equivalent to the 3 component drugs taken in a combination as single medications. The coformulated antiretroviral regimen can be quite effective in patients whose human immunodeficiency virus is sensitive to all 3 components of Atripla. However, women at risk of pregnancy, already pregnant, or nursing mothers should not take Atripla, due to the teratogenic potential of the efavirenz moiety. Adverse effects are similar to those seen with the constituent medications, including potential central nervous system effects and renal toxicity. Since its US Food and Drug administration approval, prescriptions for Atripla have increased steadily.

Impact of previous virological treatment failures and adherence on the outcome of antiretroviral therapy in 2007

Background

Combination antiretroviral treatment (cART) has been very successful, especially among selected patients in clinical trials. The aim of this study was to describe outcomes of cART on the population level in a large national cohort.

Methods

Characteristics of participants of the Swiss HIV Cohort Study on stable cART at two semiannual visits in 2007 were analyzed with respect to era of treatment initiation, number of previous virologically failed regimens and self reported adherence. Starting ART in the mono/dual era before HIV-1 RNA assays became available was counted as one failed regimen. Logistic regression was used to identify risk factors for virological failure between the two consecutive visits.

Results

Of 4541 patients 31.2% and 68.8% had initiated therapy in the mono/dual and cART era, respectively, and been on treatment for a median of 11.7 vs. 5.7 years. At visit 1 in 2007, the mean number of previous failed regimens was 3.2 vs. 0.5 and the viral load was undetectable (<50 copies/ml) in 84.6% vs. 89.1% of the participants, respectively. Adjusted odds ratios of a detectable viral load at visit 2 for participants from the mono/dual era with a history of 2 and 3, 4, >4 previous failures compared to 1 were 0.9 (95% CI 0.4–1.7), 0.8 (0.4–1.6), 1.6 (0.8–3.2), 3.3 (1.7–6.6) respectively, and 2.3 (1.1–4.8) for >2 missed cART doses during the last month, compared to perfect adherence. From the cART era, odds ratios with a history of 1, 2 and >2 previous failures compared to none were 1.8 (95% CI 1.3–2.5), 2.8 (1.7–4.5) and 7.8 (4.5–13.5), respectively, and 2.8 (1.6–4.8) for >2 missed cART doses during the last month, compared to perfect adherence.

Conclusions

A higher number of previous virologically failed regimens, and imperfect adherence to therapy were independent predictors of imminent virological failure.

Nonnucleoside reverse transcriptase inhibitor resistance and the role of the second-generation agents

OBJECTIVE

To review the current state of nonnucleoside reverse transcriptase inhibitor (NNRTI) resistance, discuss the promising role of second-generation NNRTIs, and provide insight into their clinical utility.

DATA SOURCES

Articles were identified through searches of MEDLINE (May 2000-August 2009) and International Pharmaceutical Abstracts (May 1998-August 2009), using the key words etravirine, rilpivirine, TMC125, TMC278, diarylpyrimidine, NNRTI, and resistance.

STUDY SELECTION AND DATA EXTRACTION

Clinical trials, resistance studies, and pharmacokinetic data were selected for review.

DATA SYNTHESIS

NNRTIs are an integral class of antiretroviral agents utilized for the treatment of HIV-1 infection. These agents have become preferred therapy options for treatment-naïve individuals per treatment guideline recommendations and have gained increased popularity over protease inhibitor-based antiretroviral therapy. However, available NNRTIs possess inherent characteristics, such as low genetic barrier to resistance and high degree of cross-resistance, that limit their use in HIV therapy. Due to the growing utilization of this highly efficacious antiretroviral class and the increased capability for resistance development, many HIV-infected patients have experienced treatment failure of an NNRTI. Cross-resistance makes other first-generation NNRTI agents unavailable for future use. Etravirine and rilpivirine are second-generation NNRTIs that are not significantly hampered by cross-resistance and possess potent antiretroviral activity against current NNRTI-resistant viral strains. These agents provide new and important therapy options for many HIV-infected patients.

CONCLUSIONS

NNRTI resistance is an increasing problem that may impair the chances for therapeutic success in HIV-infected patients. Novel agents such as etravirine and rilpivirine provide new, sensitive options for patients and significantly improve the rate of virologic suppression when appropriately applied.

Strand transfer inhibitors of HIV-1 integrase: bringing IN a new era of antiretroviral therapy

HIV-1 integrase (IN) is one of three essential enzymes (along with reverse transcriptase and protease) encoded by the viral pol gene. IN mediates two critical reactions during viral replication; firstly 3'-end processing (3'EP) of the double-stranded viral DNA ends and then strand transfer (STF) which joins the viral DNA to the host chromosomal DNA forming a functional integrated proviral DNA. IN is a 288 amino acid protein containing three functional domains, the N-terminal domain (NTD), catalytic core domain (CCD) and the C-terminal domain (CTD). The CCD contains three conserved catalytic residues, Asp64, Asp116 and Glu152, which coordinate divalent metal ions essential for the STF reaction. Intensive research over the last two decades has led to the discovery and development of small molecule inhibitors of the IN STF reaction (INSTIs). INSTIs are catalytic inhibitors of IN, and act to chelate the divalent metal ions in the CCD. One INSTI, raltegravir (RAL, Merck Inc.) was approved in late 2007 for the treatment of HIV-1 infection in patients with prior antiretroviral (ARV) treatment experience and was recently approved also for first line therapy. A second INSTI, elvitegravir (EVG, Gilead Sciences, Inc.) is currently undergoing phase 3 studies in ARV treatment-experienced patients and phase 2 studies in ARV naïve patients as part of a novel fixed dose combination. Several additional INSTIs are in early stage clinical development. This review will discuss the discovery and development of this novel class of antiretrovirals. This article forms part of a special issue of Antiviral Research marking the 25th anniversary of antiretroviral drug discovery and development, Vol 85, issue 1, 2010.

Efavirenz: a decade of clinical experience in the treatment of HIV

Efavirenz, a non-nucleoside reverse transcriptase inhibitor, has been an important component of the treatment of HIV infection for 10 years and has contributed significantly to the evolution of highly active antiretroviral therapy (HAART). The efficacy of efavirenz has been established in numerous randomized trials and observational studies in HAART-naive patients, including those with advanced infection. In the ACTG A5142 study, efavirenz showed greater virological efficacy than the boosted protease inhibitor (PI), lopinavir. Efavirenz is more effective as a third agent than unboosted PIs or the nucleoside analogue abacavir. Some, but not all, studies have suggested that efavirenz (added to two nucleoside reverse transcriptase inhibitors) is more effective than nevirapine. Virological and immunological responses achieved with efavirenz-based HAART have been maintained for 7 years. Dosing convenience predicts adherence, and studies have demonstrated that patients can be switched from PI-based therapy to simplified, once-daily efavirenz-based regimens without losing virological control. The one-pill, once-daily formulation of efavirenz plus tenofovir and emtricitabine offers a particular advantage in this regard. Efavirenz also retains a role after failure of a first PI-based regimen. Efavirenz is generally well tolerated: rash and neuropsychiatric disturbances are the most notable adverse events. Neuropsychiatric disturbances generally develop early in treatment and they tend to resolve with continued administration, but they are persistent and troubling in a minority of patients. Efavirenz has less effect on plasma lipid profiles than some boosted PIs. Lipodystrophy can occur under treatment with efavirenz but it may be reduced if the concurrent use of thymidine analogues is avoided. Efavirenz resistance mutations (especially K103N) can be selected during long-term treatment, underscoring the importance of good adherence. Recent data have confirmed that efavirenz is a cost-effective option for first-line HAART. In light of these features, efavirenz retains a key role in HIV treatment strategies and is the first-line agent recommended in some guidelines.

[Clinical data I. Clinical experience with tenofovir in combination with nonnucleoside analogue transcriptase inhibitors]

Highly active antirretroviral therapy has transformed the prognosis of patient infected with human immunodeficiency virus. The efficacy of these drugs has shifted the clinicians; attention to other therapeutic aspects like QD regimens, fixed dose combinations and clinical safety. Tenofovir disoproxil fumarate(TDF) is a nucleoside monophosphate (nucleotide) analogue that inhibits reverse trascriptase enzyme. It's administered in a q.d. regimen and it's recommended by most of the clinical guidelines as a start regimen in combination with two other drugs. Currently more than 5 years of clinical experience is accumulated and confirmed that a combination of tenofovir and a nonnucleoside analogue transcriptase inhibitor is a comfortable, safe, highly effective and low pill burden regimen.

Combination of tenofovir and emtricitabine plus efavirenz: in vitro modulation of ABC transporter and intracellular drug accumulation

Efflux proteins have been shown to greatly affect the uptake of antiretroviral drugs by cells and to hamper their access to the human immunodeficiency virus type 1 replication site. This study evaluated the factors that may lead to drug-drug interactions between emtricitabine (FTC), tenofovir (TFV), and efavirenz (EFV), including the modulation of efflux transporter expression and function. Peripheral blood mononuclear cells from healthy volunteers were used to determine whether or not an interaction between antiretroviral drugs and target cells occurred in any combination of FTC, TFV, EFV, FTC-TFV, TFV-EFV, or FTC-TFV-EFV. Following 20 h of treatment, intracellular drug concentrations were measured by liquid chromatography-tandem mass spectrometry. Efflux transporter functionality and inhibitor drug properties were assessed by measuring fluorescent dye efflux. ABCB1 (P-glycoprotein), ABCC 1 to 6 (multidrug resistance-associated protein), and OAT (organic anion transporter) expression in response to the treatments was quantified by semiquantitative real-time PCR. Cells treated with a double combination (FTC-TFV or TFV-EFV) or the triple combination (FTC-TFV-EFV) produced higher FTC and TFV intracellular concentrations than cells treated with FTC or TFV alone. However, no change in the EFV intracellular concentration was observed. FTC tended to induce abcc5 mRNA expression and EFV tended to induce abcc1 and abcc6 mRNA expression, whereas TFV tended to reduce mdr1, abcc1, abcc5, and abcc6 mRNA expression. Under these conditions, a decrease in the functionality of ABCC was observed, and this decrease was associated with the direct inhibitory actions of these drugs. This in vitro study reveals a benefit of the combination FTC-TFV-EFV in terms of the intracellular FTC and TFV concentrations and highlights the pharmacological mechanisms that lead to this effect.

Effectiveness and Safety of Generic Fixed-Dose Combination of Tenofovir/Emtricitabine/Efavirenz in HIV-1-Infected Patients in Western India

OBJECTIVE

To assess effectiveness and safety of a generic fixed-dose combination of tenofovir (TDF)/emtricitabine (FTC)/efavirenz (EFV) among HIV-1-infected patients in Western India.

METHODS

Antiretroviral (ARV)-naive and experienced (thymidine analog nucleoside reverse transcriptase inhibitor [tNRTI] replaced by TDF) patients were started on a regimen of 1 TDF/FTC/EFV pill once a day. They were followed clinically on a periodic basis, and viral loads and CD4 counts were measured at 6 and 12 months. Creatinine clearance was calculated at baseline and at 6 months and/or as clinically indicated. Effectiveness was defined as not having to discontinue the regimen due to failure or toxicity.

RESULTS

One hundred forty-one patients who started TDF/FTC/EFV before 1 June 2007 were eligible. Of these, 130 (92.2%) and 44 (31.2%) had 6- and 12-months follow-up, respectively. Thirty-five percent of the patients were ARV-naive. Eleven patients discontinued treatment (4 for virologic failure, 1 for grade 3-4 central nervous system disturbances, 4 for grade 3-4 renal toxicity, and 2 for cost). Ninety-six percent of patients were virologically suppressed at 6 months. Frequency of TDF-associated grade 3-4 renal toxicity was 2.8%; however, 3 of these patients had comorbid conditions associated with renal dysfunction.

CONCLUSION

A fixed-dose combination of generic TDF/FTC/EFV is effective in ARV-naive and experienced patients. Although frequency of severe renal toxicity was higher than has been reported in the literature, it was safe in patients with no comorbid renal conditions.