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.

Antiretroviral medication adherence and the development of class-specific antiretroviral resistance

OBJECTIVE

To assess the association between antiretroviral adherence and the development of class-specific antiretroviral medication resistance.

DESIGN AND METHODS

Literature and conference abstract review of studies assessing the association between adherence to antiretroviral therapy and the development of antiretroviral medication resistance.

RESULTS

Factors that determine class-specific adherence-resistance relationships include antiretroviral regimen potency, viral fitness or, more specifically, the interplay between the fold-change in resistance and fold-change in fitness caused by drug resistance mutations, and the genetic barrier to antiretroviral resistance. During multidrug therapy, differential drug exposure increases the likelihood of developing resistance. In addition, antiretroviral medications with higher potency and higher genetic barriers to resistance decrease the incidence of resistance for companion antiretroviral medications at all adherence levels.

CONCLUSION

Knowledge of class-specific adherence-resistance relationships may help clinicians and patients tailor therapy to match individual patterns of adherence in order to minimize the development of resistance at failure. In addition, this information may guide the selection of optimal drug combinations and regimen sequences to improve the durability of antiretroviral therapy.

Treatment intensification does not reduce residual HIV-1 viremia in patients on highly active antiretroviral therapy

In HIV-1-infected individuals on currently recommended antiretroviral therapy (ART), viremia is reduced to <50 copies of HIV-1 RNA per milliliter, but low-level residual viremia appears to persist over the lifetimes of most infected individuals. There is controversy over whether the residual viremia results from ongoing cycles of viral replication. To address this question, we conducted 2 prospective studies to assess the effect of ART intensification with an additional potent drug on residual viremia in 9 HIV-1-infected individuals on successful ART. By using an HIV-1 RNA assay with single-copy sensitivity, we found that levels of viremia were not reduced by ART intensification with any of 3 different antiretroviral drugs (efavirenz, lopinavir/ritonavir, or atazanavir/ritonavir). The lack of response was not associated with the presence of drug-resistant virus or suboptimal drug concentrations. Our results suggest that residual viremia is not the product of ongoing, complete cycles of viral replication, but rather of virus output from stable reservoirs of infection.

The relationship between neuropsychological functioning and HAART adherence in HIV-positive adults: a systematic review

Combination antiretroviral therapy has helped extend the lives of persons infected with HIV; however, the efficacy of highly active antiretroviral therapy (HAART) regimens depends, in part, on the consistency with which the medications are taken. In this paper, we review 11 empirical studies conducted in Western developed nations that utilized psychometrically valid neuropsychological measures to examine the relationship between cognitive functioning and HAART adherence. In general, impaired neuropsychological functioning--particularly within the domains of executive functioning and problem solving, learning and memory, attention and working memory, and global cognitive functioning--was associated with lower medication adherence across studies. However, inconsistent operationalizations of neuropsychological impairment and medication adherence employed in these studies, as well as the paucity of longitudinal data to support temporal relationships, may attenuate these conclusions. We conclude with a set of research recommendations that may help to improve the rigor of future studies and clarify questions left unanswered due to methodological limitations of existing studies.

Role of the pharmacist in pre-exposure chemoprophylaxis (PrEP) therapy for HIV prevention

With a global estimate of 2.5 million new infections of HIV occurring yearly, discovering novel methods to help stem the spread of the virus is critical. The use of antiretroviral chemoprophylaxis for preventing HIV after accidental or occupational exposure and in maternal to fetal transmission has become a widely accepted method to combat HIV.

Based on this success, pre-exposure chemoprophylaxis (PrEP) is being explored in at-risk patient populations such as injecting drug users, female sex workers and men who have sex with men. This off-label and unmonitored use has created a need for education and intervention by pharmacists and other healthcare professionals.

Pharmacists should educate themselves on PrEP and be prepared to counsel patients about their means of obtaining it (e.g. borrowing or sharing medications and ordering from disreputable Internet pharmacies). They should also be proactive about medication therapy management in these patients due to clinically important drug interactions with PrEP medications. Only one trial exploring the safety and efficacy of tenofovir as PrEP has been completed thus far. However, five ongoing trials are in various stages and two additional studies are scheduled for the near future. Unfortunately, studies in this arena have met with many challenges that have threatened to derail progress. Ethical controversy surrounding post-trial care of participants who seroconvert during studies, as well as concerns over emerging viral resistance and logistical site problems, have already halted several PrEP trials. Information about these early trials has already filtered down to affected individuals who are experimenting with this unproven therapy as an “evening before pill”. The potential for PrEP is promising; however, more extensive trials are necessary to establish its safety and efficacy. Pharmacists are well-positioned to play a key role in helping patients make choices about PrEP, managing their therapy, and developing policy with an eye towards the future.

Impact of different patterns of nonadherence on the outcome of highly active antiretroviral therapy in patients with long-term follow-up

OBJECTIVES

The aim of the study was to evaluate the impact of different patterns of nonadherence on treatment outcomes in patients with long-term follow-up.

METHODS

This cohort study included patients who began highly active antiretroviral therapy during 1996-1999, with the last follow-up in 2007. Adherence was evaluated every 2 months by monitoring of pharmacy refills and by using self-reports. Patients were considered nonadherent at a specific visit when less than 90% of the prescribed drugs had been taken. Adherence was categorized as follows. (A) Continuous adherence: a patient had to be adherent in all of the evaluations throughout the period of follow-up. (B) Treatment interruption: drugs were not taken for more than 3 days, for any reason. Treatment failure was defined as viral load >500 HIV-1 RNA copies/mL or death. Cox proportional risk models were used to calculate adjusted relative hazards (ARHs) of treatment failure.

RESULTS

A total of 540 patients were included in the study, with a median follow-up of 8.3 years. Only 32.78% of patients achieved and maintained continuous adherence, and 42.78% of patients had treatment interruptions. Noncontinuous adherence [ARH 1.48; 95% confidence interval (CI) 1.02-2.14] and treatment interruptions (ARH 1.39; 95% CI 1.04-1.85) were associated with treatment failure for the overall cohort; however, for patients with more than 3 years of follow-up, only treatment interruptions were independently associated with treatment failure.

CONCLUSIONS

Only one-third of patients managed to achieve continuous adherence, and almost half of the patients had treatment interruptions, which have a particularly marked effect on treatment outcomes over the long term.

A new application of spatiotemporal analysis for detecting demographic variations in AIDS mortality: an example from Florida

The purpose of the present study was to characterize, geographically and temporally, the patterns of acquired immune deficiency syndrome (AIDS) death disparity in 67 Florida jurisdictions, and to determine if the detected trends varied according to age, race, and sex. The space-time scan statistic proposed by Kulldorff et al was used to examine the excess AIDS deaths that occurred between 1987 and 2004. Results were geographically referenced in maps using EpiInfo and EpiMap made available by the Centers for Disease Control. Miami-Dade and the nearby counties including Broward, Martin, and Palm Beach are the most likely clusters (observed/expected: 1505.16) with temporal dimension (also called cluster's age) persisting from 1996 to the present. Union county had the longest cluster for the cluster period 1987-1998, but not for 1999-2004. African-Americans contributed to more clusters compared with whites. Time trends indicated that AIDS mortality peaked in 1995 and then sharply dropped until 1998, when the decrease stopped. By accounting for the temporal dimension of disease clustering, the present study revealed the persistence of geographic clusters, which is not often provided by other geographic detection methods. These findings may be informative for medical resource allocation and better focus public health intervention strategies for AIDS care.

Good adherence to HAART and improved survival in a community HIV/AIDS treatment and care programme: the experience of The AIDS Support Organization (TASO), Kampala, Uganda

Background

Poor adherence to highly active antiretroviral therapy (HAART) may result in treatment failure and death. Most reports of the effect of adherence to HAART on mortality come from studies where special efforts are made to provide HAART under ideal conditions. However, there are few reports of the impact of non-adherence to HAART on mortality from community HIV/AIDS treatment and care programmes in developing countries. We therefore conducted a study to assess the effect of adherence to HAART on survival in The AIDS Support Organization (TASO) community HAART programme in Kampala, Uganda.

Methods

The study was a retrospective cohort of 897 patients who initiated HAART at TASO clinic, Kampala, between May 2004 and December 2006. A total of 7,856 adherence assessments were performed on the data. Adherence was assessed using a combination of self-report and pill count methods. Patients who took ≤ 95% of their regimens were classified as non-adherent. The data was stratified at a CD4 count of 50 cells/mm³. Kaplan Meier curves and Cox proportional hazards regression models were used in the analysis.

Results

A total of 701 (78.2%) patients had a mean adherence to ART of > 95%. The crude death rate was 12.2 deaths per 100 patient-years, with a rate of 42.5 deaths per 100 patient-years for non-adherent patients and 6.1 deaths per 100 patient-years for adherent patients. Non-adherence to ART was significantly associated with mortality. Patients with a CD4 count of less than 50 cells/mm³ had a higher mortality (HR = 4.3; 95% CI: 2.22–5.56) compared to patients with a CD4 count equal to or greater than 50 cells/mm³ (HR = 2.4; 95% CI: 1.79–2.38).

Conclusion

Our study showed that good adherence and improved survival are feasible in community HIV/AIDS programmes such as that of TASO, Uganda. However, there is need to support community HAART programmes to overcome the challenges of funding to provide sustainable supplies particularly of antiretroviral drugs; provision of high quality clinical and laboratory support; and achieving a balance between expansion and quality of services. Measures for the early identification and treatment of HIV infected people including home-based VCT and HAART should be strengthened.

Randomized study of dual versus single ritonavir-enhanced protease inhibitors for protease inhibitor-experienced patients with HIV

PURPOSE

To compare activity and safety of a regimen containing lopinavir/ritonavir (LPV/r) + fosamprenavir (FPV) to regimens with LPV/r or FPV + r and to test the hypothesis that a ritonavir-enhanced dual protease inhibitor (PI) regimen has better antiviral activity.

METHOD

This study was a multicenter, open-label, randomized study. HIV-infected adults with prior PI failure were selectively randomized based on prior PI experience to either LPV/r, FPV + r, or LPV/r + FPV. All patients received tenofovir DF and 1 to 2 nucleoside reverse transcriptase inhibitors.

RESULTS

Baseline characteristics were similar across arms. Study enrollment and follow-up were stopped early (N = 56) because pharmacokinetic analyses showed significantly lower LPV and FPV exposures in the dual-PI arm. At Week 24, proportions achieving >1 log10 decline in HIV RNA or <50 copies/mL in the dual-PI versus single-PI arms combined were 75% vs. 61% in intent-to-treat (ITT, p = .17) and 100% vs. 64% in as-treated (AT) analyses (p = .02), respectively. Median CD4+ T cell/mm3 increases were 81 vs. 41 (ITT, p = .4) and 114 vs. 43 (AT, p = .08), respectively. Clinical events and toxicity rates were not different between arms.

CONCLUSION

The trial was unable to show a difference between dual versus single PIs in ITT analyses but favored dual PIs in AT analyses.