Source: DGNews  |  Posted 1 year ago

By Ric Susman

SAN FRANCISCO -- February 22, 2010 -- A fixed-dose combination antiretroviral pill improves adherence to treatment regimens among people with HIV, researchers said here at the 17th Conference on Retroviruses and Opportunistic Infections (CROI).

“In a difficult to treat population of patients enriched for substance abuse, psychiatric illness, and limited access to housing we have discovered that adherence to a fixed-dose combination antiretroviral pill was much higher than observed in other commonly used regimes,” said David Bangsberg, MD, Harvard Medical School, and Massachusetts General Hospital, Boston, Massachusetts.

Dr. Bangsberg and colleagues studied 57 patients from this difficult-to-treat population (38 men and 19 women), of which 48 said that at one time or another they would have been classified as homeless. In addition, 72% of the group admitted to intravenous drug abuse. The patient pool had a mean age of 44.3 years.

“Combination antiretroviral therapy requires lifelong adherence to regimes that have significant side effects and have complex dosing schedules,” said Dr. Bangsberg during his poster presentation on February 17.

Patients who were selected for the study were identified from an existing cohort of HIV-positive homeless to marginally housed persons and were supplemented by the recruitment efforts of the public health clinics of the Tenderloin and Mission districts of the city of San Francisco.

The patients had to maintain a regime that consisted of adherence to their programs for at least 6 months.

The researchers compared adherence outcomes between groups of patients who received a daily fixed dose of efavirenz, emtricitabine, and tenofovir in a single pill and were compared with other patients on combination antiretroviral therapy treated with a ritonavir-boosted protease inhibitor, an unboosted protease inhibitor, or non-nucleoside reverse transcriptase inhibitors who were recruited from single room occupancy hotels, free meal food programs, and homeless shelters.

Patients were recruited within 6 months of treatment initiation. Adherence was followed for 6 months using unannounced pill counts at the usual place of residence.

Mean adherence to the efavirenz-based single-dose treatment was about 86%. Adherence to all non-one-pill daily regimens was about 73% (P = .0014). “It is possible that the greater efficacy of the regime we established maybe due in part to its more recent use, when the role of adherence was more widely appreciated,” Dr. Bangsberg suggested.

Despite the nature of the treatment population, he noted that the single pill regimen “was associated with comparable if not greater virologic efficacy than that observed with historical data. The efficacy of the fixed-dose combination product was particularly evident at lower adherence levels, an observation consistent without prior findings and likely related in part to the pharmacokinetic profile of efavirenz and perhaps tenofovir/emtricitabine.”

Funding for this study was provided by Gilead Sciences, Bristol-Myers Squibb, and the National Institutes of Health.

Presentation title: A One-Pill, Once-Daily Fixed-Dose Combination of Efavirenz, Emtricitabine, and Tenofovir Disoproxil Fumarate Regimen Is Associated With Higher Unannounced Pill Count Adherence Than Non-One-Pill, Once-Daily Regimens. Abstract 510