NPR story of HIV drugs being used as recreational street drugs. Apparently this is a real problem in South Africa, although the issue has not generated a lot of press to date.
People crush anti-HIV drugs such as efavirenz and or ritonavir and mix these together with illicit substances (such as methamphetamine, opiates or marijuana) and smoke the concoction. In South Africa one such mixture is dubbed "whoonga").
Efavirenz can cause neuropsychiatric side effects (things such as vivid dreams). Ritonavir may boost the effect of other illicit substances.
A 2011 article on whoonga use from the BBC provides a nice overview of this problem in South Africa. A nice commentary piece published in the The Lancet Infectious Diseases on the recreational use of HIV drugs by Grelotti and colleagues (and on which the above NPR story was based) can be found here.
A major problem related to recreational HIV drug use is the emergence of anti-HIV drug resistance. HIV is a viral illness that requires multiple different anti-viral medications used in concert to treat effectively. When the virus is exposed to these drugs intermittently or not in combination drug resistance can emerge rapidly. Smoking "whoonga" essentially does just this: exposes people to intermittent levels of single anti-HIV drugs, thus allowing HIV to develop resistance to that single agent. This has serious consequences for the drug user if they are HIV positive, and to entire communities. If an HIV positive whoonga user develops efavirenz resistance, for instance, they can then pass that resistant virus on to another person.
In resource-limited settings sophisticated drug resistance testing is often not available, further complicating the ability to identify patients who have acquired resistance through recreational HIV drug use, or from contact with a recreational drug user.
The article by Grelotti and colleagues also outlines other potential consequences: diversion of HIV drugs, criminal behavior related to HIV drug diversion that can endanger patients and healthcare providers, et cetera. These authors call for more research into this issue and enhanced screening for recreational HIV drug use by clinicians.