Efavirenz : Its use with other ARVs

ANTIRETROVIRAL therapy offers highly effective and successful treatment for patients infected with HIV. The combination of these medications has consistently demonstrated durability over the past decade. However, the role of the patient in this success is vital. Patient adherence to the prescribed antiretroviral combination is known to improve viral suppression, slow progression to AIDS, and is considered a cornerstone in preventing the development of antiretroviral resistance.1 Ensuring that all patients initiating an antiretroviral combination understand the importance of adherence as part of their overall programme is an important component of the care of HIV-infected patients. Commonly quoted statistics based on data collected during the late 1990s estimate that a minimum of 95% adherence is desired to ensure a successful antiretroviral treatment.2 These data were based on available antiretroviral therapies available at that time, specifically two nucleoside reverse transcriptase inhibitors (NRTIs) plus a protease inhibitor (PI), often dosed thrice daily. Over the past several years, other antiretroviral strategies have become more commonly employed, such as nonnucleoside reverse transcriptase inhibitors (NNRTIs) and boosted PIs, allowing for less frequent dosing. Accumulating data have suggested that the level of adherence that is required to prevent the development of drug-resistant virus is a complex relationship and may be related to the combination therapy being used. For nonboosted PI-based therapies, patients who take most of their doses of medications, approximately 70-80%, may have an increased risk of drug-resistant virus as compared to those patients who are highly adherent or very poorly adherent. Boosted PI regimens may have an overall lower risk of developing risk at any adherence level, with the greatest risk of resistance at approximately 50% adherence. Finally, NNRTIbased regimens will likely result in the development of few resistance mutations in any patient who is highly adherent, but will easily develop resistance in the presence of any viral replication. See Figure 1 for a visual interpretation of these data from Bangsberg et al.1 Regardless of the exact adherence required, these data still suggest that care providers and patients should be striving for as close to 100% adherence as possible to ensure therapeutic success. Because of this large commitment the patient is undertaking at the beginning of antiretroviral therapy, it is essential to ensure the patient possesses the motivation to make this therapy successful. Engaging the patient in the reasons that adherence is necessary, as well as the implications of non-adherence will help them understand their role in making antiretroviral drugs work for them. Ensuring the patient understands the dose, frequency, timing of medications with food or at certain times of day is crucial at the initiation of therapy. Also, explaining potential side effects, and management of these side effects, will help the patient overcome the initial difficulty with starting these regimens. Consistent reinforcement of adherence from physicians, nurses, counsellors, and pharmacists at each clinic visit will help ensure the patient understands the importance of this aspect of care. Finally, including any patient support system, friends, family, or neighbours, in the reinforcement of the importance of medication adherence will help keep the patient motivated between clinic visits and provide the much needed support for the patient throughout therapy.3 References 1.Bangsberg DR, Moss AR, Deeks SG. Paradoxes of adherence and drug resistance to HIV antiretroviral therapy. J Antimicrob Ther 2004; 53:696-699. 2.Paterson DL, Swindells S, Mohr J, et al. Adherence to protease inhibitor therapy and outcomes in patients with HIV infection. Ann Intern Med 2000; 133: 21-30. 3.Tuldra A, Wu AW. Interventions to improve adherence to antiretroviral therapy. JAIDS 2002; 31(Suppl 3):S154-S157.