Interactions between HIV medications and crystal meth, mephedrone, ketamine
In this edition of HIV Update, we summarise an expert review which outlines what doctors know about the potential interactions between HIV medications and recreational drugs. Prepared by experts based in the UK, the review focuses on the drugs that are most commonly used by gay men living with HIV in the UK.
The most important finding of the review is that the two prescribed medications which are most likely to be involved in harmful interactions with recreational drugs are ritonavir (Norvir) and cobicistat (Tybost).
The potential for interactions between medications taken to treat HIV and recreational drugs was also the topic of the last edition of HIV Update. The study we reported on then highlighted the fact that some people living with HIV intentionally miss doses of their HIV treatment when they use recreational drugs, because of worries about interactions.
However, many of the participants in that study were using cannabis – which is not thought to interact dangerously with anti-HIV drugs. Skipping doses of HIV treatment would do more harm than taking HIV treatment together with cannabis.
The present review gives information on when drug interactions are of concern, and when they are not. A drug interaction can occur when two or more drugs are in the body at the same time. The interaction between the two drugs may decrease or increase the effectiveness of either one or both drugs. Similarly the interaction may decrease or increase the side-effects of the drugs.
Both ritonavir (Norvir) and cobicistat (Tybost) are boosting agents, taken in order to raise levels of other antiretroviral drugs. Adding a small dose of one of these agents to a drug makes the liver break down the primary drug more slowly, which means that it stays in the body for longer times or at higher levels. Without the boosting agent, the prescribed dose of the primary drug would be ineffective.
The same mechanism affects some recreational drugs – crystal meth, MDMA, mephedrone, ketamine, Viagra and other erectile dysfunction drugs, and Valium and other benzodiazepines. The boosting agent makes the liver process the recreational drug more slowly, resulting in the recreational drug remaining in the body for longer or in greater concentrations.
Sometimes, this can result in serious side-effects or an overdose. Doctors don’t know how often this happens, but a handful of deaths have been recorded.
If your HIV treatment includes a protease inhibitor, you are probably using one of these boosting agents. Cobicistat is also taken alongside the new integrase inhibitor elvitegravir, including in a single tablet regimen called Stribild. (For more information on the treatments which are affected, see the full article on aidsmap.com).
If you are taking one of these medications and also sometimes use crystal meth, MDMA, mephedrone, ketamine, erectile dysfunction drugs or benzodiazepines, a frank discussion with your HIV doctor or pharmacist would be helpful. If you don’t want to stop or can’t stop using recreational drugs, switching to an HIV treatment with less potential for interactions might be an option.
A different interaction can occur with the non-nucleoside reverse transcriptase inhibitors (NNRTIs) efavirenz, nevirapine and etravirine. The interaction may result in levels of the recreational drug being lower than would normally be expected. This applies to cocaine, ketamine and erectile dysfunction drugs.
The experts say that there are several anti-HIV drugs which are not thought to have problems with interactions. Similarly, alcohol, cannabis, poppers, heroin and other opioids are unlikely to interact with HIV medications.
The University of Liverpool's HIV Drug Interactions website publishes a table summarising the interactions between antiretrovirals and recreational drugs.
Link between hepatitis C and heart problems
A study has shown that people who have hepatitis C are more likely to have hardening of the coronary artery, which is an important early warning sign of cardiovascular disease. The study compared the arteries of almost 1000 American men, including individuals who had hepatitis C and HIV, and individuals who did not.
People who had HIV were more likely to have hardening of their arteries, as were men who had hepatitis C. The results show that hepatitis C affects many aspects of health, not just those directly related to the liver. People who have hepatitis C may be able to reduce their risk of a heart attack or other heart problems by getting more exercise, improving their diet, stopping smoking and taking a statin.
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