HIV Drug-Drug Interactions

HIV Drug-Drug Interactions

Download PDF version of this document (25 pages)
http://www.hivguidelines.org/wp-content/uploads/a-hiv-drug-drug-interactions-04-14-2010.pdf

Drug-Drug Interactions Between ARV Agents, Medications Used in Substance Use Treatment, and Recreational Drugs


Updated April 2010


I. INTRODUCTION
General Recommendations:
The clinician should conduct a thorough medication history at each visit that includes prescription medications, including those prescribed by other providers, over-the-counter medications, recreational drugs, and herbal/alternative therapies.

The clinician should classify common substrates, inducers, and inhibitors of the CYP450 system used in HAART to accurately predict drugs that may lead to significant drug interactions (see Table 2 and Appendix A).

The clinician should identify dietary restrictions with ARV drugs so that food-drug interactions can be avoided.

Drug interactions have become an increasingly complex challenge for clinicians treating patients with HIV infection. Current treatment guidelines recommend the use of a combination of at least three ARV drugs for the treatment of HIV-infected patients. In addition to medications to treat HIV infection, patients are often receiving therapy for comorbid conditions and prophylaxis of opportunistic infections. Because of the number of drugs that the HIV-infected patient receives, clinicians often must rely on clinical judgment and are forced to predict drug interactions without supporting data.

Although no specific guidelines exist on how to prevent drug interactions, the most important strategy to successful prevention is to conduct a thorough medication history at each visit, including questions about prescription, over-the-counter, herbal, and recreational drugs and prescriptions received from other healthcare providers. Clinicians’ self-education about drugs that are associated with clinically significant drug interactions with HAART is important for clinicians to avoid drug interactions or to monitor patients for virologic failure or toxicity.

Key Point:

► Clinicians should instruct their patients to notify them of any new medication the patient is taking.
► Providing patients with a detailed list of drugs that are contraindicated with HAART may help the patient to identify significant drug interactions.


This chapter provides an overview of known and potential drug interactions encountered with the use of HAART. Included is a description of common mechanisms of drug interactions, a review of the route of elimination for ARV drugs, an overview of common drug interactions encountered in this setting, and specific recommendations for management of drug interactions encountered with HAART.



II. CLASSIFICATION OF DRUG INTERACTIONS
Drug interactions can be classified into two broad categories: 1) interactions altering pharmacokinetics and 2) interactions affecting pharmacodynamics. Although both have the potential to be problematic in patients receiving HAART, pharmacokinetic interactions are more common and more difficult to predict due to the complex nature of drug metabolism. Clinically significant drug interactions are generally those that produce at least a 30% change in pharmacokinetic parameters, but this may vary. Table 1 outlines the classification of common drug interactions with supporting examples.

open here to see the full-text (large):
http://www.hivguidelines.org/clinical-guidelines/adults/hiv-drug-drug-interactions/