NEW YORK (Reuters Health) – Maraviroc-containing regimens appear to be safe and well tolerated, compared with tenofovir-emtricitabine (TDF-FTC), for preventing HIV infection in women, according to results from a phase 2 trial.
“The only FDA-approved HIV preexposure prophylaxis (PrEP) regimen is the combination of tenofovir disoproxil fumarate and emtricitabine (co-formulated into one pill),” Dr. Roy M. Gulick of Weill Cornell Medical College, New York, told Reuters Health by email. “However, there are some issues with these 2 drugs; in particular, tenofovir diphosphate (the active compound) drug levels are 100 times lower in the female genital tract vs. colonic-rectal mucosa – other options are needed. If proven efficacious, maraviroc could offer an alternative for HIV PrEP for women.”
Dr. Gulick and colleagues compared the safety and tolerability of three maraviroc (MVC)-containing HIV PrEP regimens (MVC alone, MVC plus TDF, and MVC plus FTC) versus TDF-FTC in 188 women at risk for HIV infection.
About a third of women stopped using their assigned medication by week 48, with no difference among the groups, according to the August 21 Annals of Internal Medicine online report.
Thirty-five women (19%) experienced 48 grade 3 or 4 adverse events, fewer than 25% of which were deemed related to study drugs. The rates of these events did not differ significantly among the groups.
Medications were detected in plasma from 65% of women at week 24 and 60% at week 48, with no significant differences among the groups.
No participants acquired HIV infection during the study, but four were diagnosed with other sexually transmitted infections (1 with gonorrhea and 3 with chlamydia).
“Although we enrolled 188 women who reported being at risk for HIV infection at study entry, we were surprised to see that very few participants experienced sexually transmitted infections or required HIV post-exposure prophylaxis on the study,” Dr. Gulick said. “We guessed that these women may not have been very high risk for HIV. The fact that no new HIV infections occurred on our study could have been due to the fact that the study population was at low risk (vs. that the HIV PrEP regimens worked).”
“This was a phase 2 safety/tolerability study and was not designed to test the efficacy of the study regimens to prevent HIV infection,” he said. “Larger phase 3 studies of maraviroc-based regimens would be required to demonstrate efficacy (as well as safety/tolerability in a larger group of participants).”
Dr. Edwina Wright from University of Melbourne, Prahran, Victoria, Australia, told Reuters Health by email, “I think that the discontinuation rate was relatively high, but over the course of 48 weeks the circumstances of people’s lives do change and PrEP may no longer be required. In addition, if people perceived their risk of HIV to be low, during the study that may have made it easier for participants to justify ceasing PrEP and this study population, by design, was not at high risk of acquiring HIV infection.”
“We still need to determine if maraviroc has efficacy in HIV prevention in women who are at high risk of HIV infection,” she said. “If that is determined, then maraviroc, either alone or formulated with a second antiretroviral agent, is likely to play an important role in HIV PrEP for women. Tenofovir-containing PrEP regimens are less forgiving for women than for men because women need to take 7 doses per week weekly to maintain high levels of protection; men need only 4 or more tenofovir-containing doses per week to achieve those same levels of protection.”
“It is vital that new PrEP medications are tested in women,” Dr. Wright added. “We need more information on the safety of maraviroc during pregnancy.”
SOURCE: http://bit.ly/2x7rXeX
Ann Intern Med 2017.
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