In Canada and other high-income countries there are at least 24 anti-HIV drugs from which doctors can choose when writing a prescription. A combination of at least three of these drugs, chosen from different classes, is commonly called ART (the older name is HAART). This apparent abundance of choice masks an underlying reality -- many of the drugs listed are older, are not as effective and are not as well tolerated as newer therapies.
To help guide doctors, nurses and patients when making decisions about the initial use of ART, the U.S. Department of Health and Human Services (DHHS) has been producing treatment guidelines for several decades. The DHHS guidelines are generally seen as the most comprehensive and detailed of all HIV treatment guidelines. Furthermore, the DHHS guidelines have been noted for their forward thinking and influence guidelines in other countries and regions.
In the latest update to the guidelines, medical and scientific advisors to the DHHS have greatly simplified the recommendations for the initial therapy of HIV. The guidelines now state that the initial regimen should be based on a backbone of either integrase inhibitors or a protease inhibitor. This has resulted in just five regimens being recommended.
Integrase inhibitor-based regimens:
- dolutegravir (an integrase inhibitor sold under the brand name Tivicay) + Kivexa (abacavir + 3TC) or a single pill containing all three drugs taken once daily and sold as Triumeq
- dolutegravir + Truvada (a single pill containing tenofovir + FTC)
- Stribild -- a fixed-dose combination of elvitegravir + cobicistat + Truvada. Elvitegravir is an integrase inhibitor. Cobicistat is a boosting agent that raises and maintains levels of elvitegravir in the blood so that once-daily dosing is possible.
- raltegravir (an integrase inhibitor sold under the brand name Isentress) + Truvada
A protease inhibitor-based regimen
- darunavir (a protease inhibitor sold under the brand name Prezista) + a small dose of ritonavir (Norvir) + Truvada
Although ritonavir is a protease inhibitor, when used in low doses it acts to boost and maintain levels of darunavir (or other drugs) so that once-daily dosing is possible.
Although not mentioned in the guidelines, a new fixed-dose formulation of darunavir + the booster cobicistat has become available in Canada and other high-income countries. This new formulation is called Prezcobix.
The updated recommendations from the DHHS have surprised some people because therapies that were once commonly favoured even a few years ago -- efavirenz (Sustiva, Stocrin and in Atripla), Kaletra (lopinavir + ritonavir), atazanavir (Reyataz) + ritonavir, and rilpivirine (Edurant and in Complera and Eviplera) -- have been left behind.
The recommendations for the regimens for first-line (initial) therapy use are largely based on the results of large, well-designed clinical trials.
Panel on Antiretroviral Guidelines for Adults and Adolescents. Guidelines for the use of antiretroviral agents in HIV-1-infected adults and adolescents. Department of Health and Human Services. 8 April 2015.