Once-daily antiretroviral therapy: Spanish Consensus Statement

Didanosine, lamivudine-emtricitabine and efavirenz as initial therapy in naive patients

There are currently several suitable and different antiretroviral regimens to start highly active antiretroviral therapy (HAART), and many clinicians and patients prefer once-daily therapy. The efficacy and potency of efavirenz (EFV) has been established in many clinical trials and cohort studies; its pharmacokinetics, allowing for a convenient once-daily administration, make EFV one of the first agents to be included in once-daily regimens in naive patients. The two nucleoside reverse transcriptase inhibitors (NRTIs) accompanying the third drug have become the central skeleton, or the 'backbone' of the therapeutic scheme. Among the different NRTI pairs, a didanosine-lamivudine (3TC) or emtricitabine backbone for combination antiretroviral therapy may be a good option compared with any current NRTI-combinations due to its security, tolerance and once-daily dose. In this article, we review the advantages and drawbacks of didanosine-XTC-EFV as the initial regimen of HAART in HIV-infected patients.

Antiretroviral therapy in HIV-infected patients: a proposal to assess the economic value of the single-tablet regimen

BACKGROUND

The aim of this study was to assess the economic value of a reduced number of pills in patients infected with the immunodeficiency virus (HIV) and on highly active antiretroviral therapy by a cost-effectiveness model.

METHODS

An incremental cost-effectiveness analysis of efavirenz, tenofovir, and emtricitabine (TDF-FTC-EFV) as a single-tablet regimen versus a multipill regimen, with reference to untreated HIV-infected patients, was carried out from the perspective of the Italian National Health Service. The comparisons were performed with the help of a Markov decision model over a 10-year time horizon. Based on the ADONE (ADherence to ONE pill) study, it was then possible to identify the utility score increment in patients switching from a multipill regimen of TDF-FTC + EFV therapy to a single-tablet regimen.

RESULTS

The single-tablet regimen (0.755 quality-adjusted life-years [QALYs]/year) resulted in better patient quality of life, with a higher number of QALYs than for the TDF-FTC + EFV multipill regimen (0.716 QALYs/year). The single-tablet regimen was the most cost-effective treatment strategy, with an incremental cost-effectiveness ratio of €22,017.00 versus €26,558.00 for the multipill regimen. A 24% decrease in cost of the multipill regimen determined equivalence with the single-tablet regimen in terms of the incremental cost-effectiveness ratio. Univariate sensitivity and probabilistic analysis carried out on the main variables did not highlight significant variations with respect to the base case scenario.

CONCLUSION

The single-tablet regimen resulted in better adherence, and therefore better quality of life as perceived by patients, corresponding to a €4541.00 lower cost-effectiveness ratio per QALY versus the multipill regimen, with a 17% lower cost in favor of the single-tablet regimen. The value determined could be used to identify a maximum potential "premium price" of 29% to be assigned to therapeutic regimens proposing a single-tablet regimen for HIV-infected patients.

Short-term virological efficacy, immune reconstitution, tolerance, and adherence of once-daily dosing of didanosine, lamivudine, and efavirenz in HIV-1-infected African children: ANRS 12103 Burkiname

Access to antiretroviral therapy (ART) and routine laboratory monitoring are limited for HIV-1-infected children from sub-Saharan Africa. This trial conducted in Bobo-Dioulasso, Burkina Faso, aimed to describe the biological efficacy, tolerance, and adherence of the combination of didanosine, lamivudine, efavirenz in once-daily administration among eligible HIV-1-infected children. From February 2006 to November 2007, 51 HIV-1-infected children aged from 30 months to 15 years and eligible for ART were enrolled in a phase II open clinical trial with follow-up visits every 3 months. HIV-1 genotype testing was performed in children with plasma viral load (PVL) >1000 copies per milliliter after ART initiation. Children were followed for a median of 13.4 months [interquartile range (IQR) 12.8-14.2]. At enrollment, median CD4 count was 8% (IQR = 4.5-12). PVL was 341,032 (IQR = 127,838-761,539) copies per milliliter. At 12 months, median CD4 increased significantly by +15% (P < 10(-3)), and median PVL decreases significantly by -290,500 copies per milliliter (P < 10(-4)). Hemoglobin and platelets counts increased significantly by +1.05 g/dL (P < 10(-5)) and 108,500 cells per milliliter (P < 10(-3)), respectively. Based on pill count, mean yearly adherence was 97.3%, and 48% of the children had an adherence rate ≥ 95% at the four quarterly visits. Adherence was better for girls than for boys independently of other sociodemographic variables or markers of HIV disease progression. Drug-resistant mutations were found in 11 children (21.6%). This once-daily drug combination is associated with excellent virological efficacy, immune reconstitution, and good adherence. However, the high prevalence of drug resistance mutations is a matter of concern.

Twice-daily versus once-daily antiretroviral therapy and coformulation strategies in HIV-infected adults: benefits, risks, or burden?

The recent development of once-daily antiretroviral agents and fixed-dose combination formulations has been an important development in antiretroviral regimen simplification. Recent studies indicate that once-daily antiretroviral regimens improve adherence, especially in antiretroviral-naïve patients and in difficult-to-treat populations, such as the homeless or marginally housed. However, there are potential risks with the higher peak and lower trough plasma drug concentrations that may result from certain once-daily formulations. Due to the multifactorial and complex nature of adherence behavior, clinicians' efforts to improve patient adherence should not be limited to prescribing once-daily regimens, but should also consider social support, side effect management, and adherence support tools, such as pillbox organizers and other targeted interventions. Additional research will clarify the benefits of once-daily and fixed-dose combination regimens on clinical and virologic outcomes. Comprehensive cost-benefit analysis of regimen simplification could help facilitate evidence-based decisions regarding antiretroviral regimen choices.

The future of antiretroviral therapy: challenges and needs

The introduction of combination antiretroviral therapy (cART) has substantially modified the natural history of HIV infection. At the beginning of the cART era the objective was focused on HIV-1-associated mortality and morbidity, but as this objective was accomplished other issues emerged, including toxicity, resistance and compliance with treatment. Moreover, the participation of other disease mechanisms, such as proinflammatory activity, in the so-called non-AIDS events is becoming increasingly important. To overcome these issues, therapeutic options have dramatically expanded, which has made the management of HIV-1-infected patients increasingly complex. The intense changes seen raise the question of what will be the future of HIV infection and its treatment. A projection into the future may help to reflect on current limitations, needs and research priorities, to optimize patient care. To debate on this topic a group of 38 experts has initiated The HIV 2020 Project, with the aim of reflecting on the future of HIV infection and identifying the needs that should be the attention of research in different areas. This document summarizes the group's conclusions on the future of antiretroviral treatment, presented as 20 relevant questions. Each question includes the current status of the topic and our vision for the future.

Pharmacokinetic interaction between rifampicin and the once-daily combination of saquinavir and low-dose ritonavir in HIV-infected patients with tuberculosis

OBJECTIVES

To assess plasma steady-state pharmacokinetics (PK) of rifampicin, isoniazid, saquinavir and ritonavir in HIV and tuberculosis (TB) co-infected patients, and investigate potential interactions between TB drugs and protease inhibitors (PIs).

METHODS

Open-label, single-arm, sequential PK study including 22 patients with HIV infection and TB. During the first 2 months, patients received rifampicin, isoniazid and pyrazinamide, with or without ethambutol (first PK study, n = 22). Then patients stopped pyrazinamide and ethambutol and started once-daily antiretroviral therapy (ART) with didanosine, lamivudine, ritonavir (200 mg) and saquinavir (1600 mg) (second PK study, n = 18). Patients stopped all TB drugs after 9 months continuing the same ART (third PK study, n = 15). Differences between TB drug parameters in the first and second PK studies, and between PI parameters in the second and third PK studies were used to assess interactions.

RESULTS

Rifampicin and isoniazid pharmacokinetics did not change substantially with saquinavir and ritonavir. A significant 39.5%, 34.9% and 48.7% reduction in median saquinavir AUC(0-24), C(max) and C(trough), respectively, was seen with rifampicin and isoniazid. Ritonavir AUC(0-24), C(max) and C(trough) decreased 42.5%, 49.6% and 64.3%, respectively, with rifampicin and isoniazid.

CONCLUSIONS

There was a significant interaction between saquinavir, ritonavir and rifampicin, with reduction in median plasma concentrations of saquinavir and ritonavir. Saquinavir should be given with caution in patients receiving rifampicin. Twice-daily dosing or higher saquinavir doses in once-daily administration should be tested to obtain more appropriate plasma levels.