Nowadays, most patients are on some form of once-daily antiretroviral therapy that has made HIV a more manageable chronic disease.
One of the most popular combination pills is Atripla, which is composed on efavirenz and emtricitabine/tenofovir. Efavirenz (brand name: Sustiva) is a non-nucleoside reverse transcriptase inhibitor that is metabolized by the same CYP enzymes that metabolize opioids.
Clarke et al report that in a sample population of patients who started efavirenz, a 22% increase in methadone dose was required. This infochart is helpful in looking up the specific interactions between classes of HIV medications and opioids. It should be noted that the same effect was not seen between efavirenz and buprenorphine.