7. 5 ART and recreational drug interactions: overview

There is considerable research about interactions between ART and other prescribed medications.

There is much less information about interactions between ART and recreational and illicit drugs.

Interactions summary

Although there are potential interactions between older HIV drugs and recreational and illegal drugs, there are very few concerns with modern ART using unboosted integrase inhibitors and modern NRTIs.

The main older drugs with possible interactions that are still used include:

Ritonavir and cobicistat (used to boost darunavir, other PIs and elvitegravir (now rarely used).
Older NNRTIs: efavirenz, etravirine (and nevirapine though now rarely used)
Unfortunately, some of these drugs are still used in many low- and middle-income countries where rates of HIV are still very high in people who use drugs.

For full details please see this drug interaction table from Liverpool University.
Liverpool University: ART interactions with street and recreational drugs (PDF)

Impact of drug use on HIV

Use of street and recreational drugs can also affect HIV in ways that are separate to drug interactions.

Drug use is sometimes indirectly linked to worse outcomes on ART. For example, if support for adherence is not provided or effective. Routinely missing doses of ART or clinic appointments to monitor and access ART can lead to treatment failing.
Some drugs could reduce how well the immune system can fight infections. This can be a direct effect on the immune system and an a indirect effect, if people are not eating and sleeping well because of drug use.
Recreational and street drugs can make people feel more attractive and sexual making it easier to enjoy sex. Reducing inhibitions often involves getting into situations where the risk of other infections can be higher.

Taken together, these factors can easily make HIV outcomes worse. There is a higher risk of viral load rebounding, HIV drug resistance, a lower CD4 count and increased risk of other infections.

Data from theoretical versus human studies

Theoretical interactions proposed by scientists do not always match real interactions in people.

Because these drugs are illegal, predicted interactions are not based on studies in humans but on theory, experiments in test tubes (in vitro) or tests on animals.

There are difficulties both with conducting studies and using theoretical information:

Clinical studies using illegal drugs usually needs special Government approval in most countries. Getting government support is difficult because this is seen as supporting drug use.
Illegal drugs are seldom pure. They are often have other substances added to them. They may not even contain the active ingredient that someone thinks they have bought. Finding supplies of pure drugs would, in some cases, be difficult.
There are no approved versions of drugs like cocaine. Drug companies are unwilling to manufacture test versions of drugs in their own laboratories for legal and ethical reasons, even if the government granted permission.
Illegal drugs rarely have standard doses. What could be a relatively minor interaction at one dose could be serious at another.
Some protease inhibitors have effects in real life that are opposite to those seen in the test tube. Some studies showed decreases in methadone levels in people when test tube experiments predicted an increase.
There is little financial incentive for drug companies to do this work.
Manufacturers are concerned about legal liability should they offer advice based on uncertain or incomplete information.

7. 5 ART and recreational drug interactions: overview

Interactions summary

Impact of drug use on HIV

Data from theoretical versus human studies

Further reading