Slide 61 of 76
Notes:
- Management options may vary depending upon a number of factors, including the mechanism and clinical consequences of the interaction, availability of therapeutic alternatives, patient convenience, and cost.
- Space dosing times (e.g., separate delavirdine and ddI by 1 hour) Can this be done in a practical and/or convenient way for the patient?
- Change drug dose. The potential impact of dosage manipulation on patient adherence should be carefully considered. This in turn may depend upon the drug formulations available, existing pill burden and dosing schedule, and cost. For instance, to adequately adjust for the interaction between indinavir and rifabutin, indinavir should be increased to 1 g every eight hours and rifabutin should be decreased to 150 mg daily. This can be done with no additional dosing times and minimal increase in pill burden. On the other hand, the interaction between delavirdine and rifabutin is not as straightforward to manage. With standard doses of both agents, delavirdine concentrations are decreased by 50-60%. Even with a median delavirdine dose of 600 mg three times daily, trough concentrations are often still not adequate, and rifabutin concentrations are significantly elevated. In such situations, therapeutic alternatives to either delavirdine or rifabutin need to be considered.
- Change agent (e.g., change rifabutin to azithromycin for MAC prophylaxis) What are the comparative efficacy, side effects, cost, availability, compliance issues, and drug interactions associated with the new agent?
- Take no action. In certain situations (e.g., low likelihood of an interaction occurring, minor or insignificant clinical impact of a potential interaction) the practitioner may wish to maintain the patient’s current regimen and monitor the patient’s condition.
