7. 6 ART and recreational drug interactions: ritonavir
Ritonavir and street drugs
Predicted interactions based on using full dose (1,200 mg a day). Ritonavir is now most commonly used to boost other protease inhibitors at a low dose (100-400 mg a day).
- 2 to 3 fold increase in ecstasy levels.
- 2 to 3 fold increase in levels of amphetamines.
- About 50% decrease in blood levels of heroin – 36% decrease in methadone.
- No serious interactions with cocaine.
- Significant increase in levels of sildenafil (Viagra) and similar drugs.
All protease inhibitors are processed by the body in a similar way to ritonavir, as is the non-nuke efavirenz, so there is potential for interaction with any of these drugs.
Ritonavir and the liver
Ritonavir makes the liver process many drugs more slowly (inhibition). This means that the drugs stay in the body longer times and/or at higher levels. This includes PIs – which is why ritonavir is used at low dose to make PIs more effective. It also includes amphetamines and many prescription drugs.
Ritonavir makes the liver process some drugs more quickly (induction). This means that the drugs stay in the body for shorter times and/or at lower levels. This includes heroin and other opiates, methadone plus some prescription drugs.
In 1996 a young HIV positive British man died after taking ecstasy while using ritonavir. His death was caused by an overdose. The level of ecstasy in his blood was nearly ten times the level that is expected to cause serious toxic effects, ie roughly the same as taking 22 ecstasy tablets.
This man had taken ecstasy previously with no such ill effects. This was the first time that he had taken ecstasy since adding full-dose ritonavir to his ART combination, which is why his doctors concluded that this interaction was the culprit.
Following interventions by activists, the manufacturer (Abbott) produced some theoretical information for ritonavir’s interaction with common recreational drugs.
- Interactions between ARVs and street drugs – Medical review from 2003 on the available data on interactions between differetn street and recreational drugs and antiretrovirals.
- Alcohol and HIV questions. Link to questions on alcohol and HIV shows a range of recent questions to i-Base.
Last updated: 1 December 2015.