Pharmacotherapy for HIV+ Stimulant Dependent Individuals

In 1996, the use of protease inhibitors and triple therapy known as HAART (highly active antiretroviral therapies) became widespread in the United States for the treatment of HIV. This changed the disease process from a relentless and progressive one to a chronic one, with the resulting need to focus on issues related to adherence. Because of unique aspects of viral resistance with HIV, an adherence rate of 95% or higher is required to minimize or halt the progression of the disease (DeMasi et al., 2001; Gross, Bilker, Friedman, \& Strom, 2001). Cocaine use and dependence has been found to have deleterious effects on HIV infected individuals (Fiala et al., 2005) Cocaine use hastens disease progression, increases viral loads and decreases CD4 counts(Arnsten et al., 2002; Baldwin, Roth, \& Tashkin, 1998; Hurwitz, ; Kapadia, Vlahov, Donahoe, \& Friedland, 2005; Lucas et al., 2006; Roth et al., 2002; Roth, Whittaker, Choi, Tashkin, \& Baldwin, 2005) Cocaine use correlates with increased "no show" clinic visits and decreased or no-adherence to HIV medications. (Hinkin et al., 2007; Ingersoll, 2004; Palepu, Horton, Tibbetts, Meli, \& Samet, 2004; Sharpe, Lee, Nakashima, Elam-Evans, \& Fleming, 2004) There appear to be multiple reasons for non-adherence in this substance abusing population. Factors such as forgetting and running out of medications have been implicated with substances such as crack cocaine and heroin. (Ingersoll, 2004; Kerr et al., 2004)

A medication that decreases or ceases cocaine use potentially improves adherence at clinic appointments as well as adherence to medication. In addition, it might indirectly decrease the progression of the disease. Ondansetron, a serotonin type 3 receptor antagonist (5HT3), at 4mg twice a day has been shown to have a greater rate of improvement in percentage of participants with a cocaine-free week compared to placebo in cocaine dependent non HIV infected treatment seeking individuals. (Johnson, B.A. 2006)

Ondansetron is FDA approved for chemotherapy induced nausea and vomiting, postoperative nausea and vomiting and radiation induced nausea and vomiting. Ondansetron has shown efficacy for nausea and vomiting in HIV infected individuals for palliation, as well as for diarrhea due to cryptosporidium infection.(Currow, Coughlan, Fardell, \& Cooney, 1997; Gompels et al., 1993; Schworer, Hartmann, \& Ramadori, 1994) Until recently, ondansetron's cost was prohibitive. However, as a generic drug it has become more affordable. Among the benefits of this drug is the qualitative benefits for HIV infected individuals with nausea and diarrhea as well as cocaine dependence. HIV medications can cause nausea (M. O. Johnson, Stallworth, \& Neilands, 2003; M. O. Johnson et al., 2005; O'Brien, Clark, Besch, Myers, \& Kissinger, 2003; Reynolds \& Neidig, 2002) and thus adherence might be improved with this medication in cocaine using individuals. Ondansetron is well tolerated in HIV infected individuals, and according to micromedex there are no known drug interactions with HIV medications (Gompels et al., 1993)

Ondansetron has a mild adverse events profile. In studies with cocaine dependent individuals who were not HIV infected, our group found that Ondansetron had fewer side effects than placebo (B. A. Johnson et al., 2006). Also, in that same study, Ondansetron recipients attended more sessions than those of placebo. Both of these factors make this drug an appealing option for cocaine dependent HIV infected individuals.