Treatment training manual

7. 5 ART and recreational drug interactions: overview

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

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

Interactions summary

There are many interactions between ritonavir and other drugs. All protease inhibitors (PIs) and the non-nuke efavirenz are processed by the body in a similar way to ritonavir, so there is potential for interaction with any of these.

  • Ritonavir increase levels of ecstasy and amphetamines.
  • Ritonavir, efavirenz, nevirapine reduce levels of heroin and methadone ā€“ this may lead to withdraw symptoms.
  • Some other PIs reduce levels of heroin and methadone.
  • Methadone doubles levels of AZT.

Theoretical information is not as useful as studies on humans

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 trials using illegal drugs would require permission from the (American) government. The government is reluctant to allow studies because it may be seen as ‘soft on drugs’.
  • Illegal drugs are seldom pure. They are often contaminated by other substances. They may contain little or no active ingredient. 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 opposite to those predicted in the test tube. There have been instances of 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.

Further reading

An overview of drug interactions between methadone, buprenorphine and HIV medications was published in the i-Base publication ARV4IDUs.

Last updated: 1 December 2015.