Psychopharmacologic Treatment Issues in AIDS Psychiatry
Persons with HIV and AIDS are often prescribed a plethora of medications, all of which require special attention and are based on well-defined principles. In the first part of this chapter, Drug Interaction Principles, we provide a short but essential review of these principles in order to prepare the reader to critically weigh the potential for drug interactions between psychotropics and antiretroviral therapy (ART) and those between ART and other medications. In the second part, Psychotropics and HIV, a brief review of the available literature on the effectiveness of psychotropics in treating patients with HIV is provided, followed by an overview of issues relating to drug interactions for each psychotropic or class of psychotropic. The third part of the chapter, Antiretrovirals, provides an introductory overview of currently available antiretrovirals and of medications prescribed in treating HIV/AIDS. Readers are referred to an excellent review of pharmacological treatment for persons with addictions and HIV/AIDS, by Wynn and colleagues (2005), and to Chapters 2, 6, 8, and 10 of this handbook for more information on treating substance abuse and dependence. Understanding drug–drug interactions in the care of HIV patients is essential. For a full explanation of psychotropic pharmacology and drug interactions, the reader is referred to additional texts on the subject (Cohen and Gorman, 2008; Schatzberg and Nemeroff, 2009; Wynn et al., 2009). Pharmacodynamic interactions are those that occur at the intended receptor site of a medication and involve absorption, distribution, metabolism, and excretion. ART drugs may be affected by timing with food or buffers, which is relatively predictable. Metabolic interactions are a bit more complex, as they are affected by metabolic inhibition, induction, and pharmacogenetics (the particular metabolic enzymes that a patient is born with). Metabolic interactions may occur in either phase I or II metabolic enzymes and also may include the cell membrane transporter enzymes (also known as p-glycoproteins). For a complete explanation of pharmacokinetic interactions, the reader is referred to the text by Wynn et al. (2009).