ABSTRACT
Human immunodeficiency virus (HIV) protease inhibitors are prone to drug interactions with other agents. As individuals with HIV infection live longer, the clinical significance of many interactions is becoming recognized. A 51-year-old man with HIV infection who was receiving extended-release nifedipine developed symptomatic orthostasis and heart block after starting antiretroviral therapy that included nelfinavir. He experienced dizziness, fatigue, and hypotension and developed complete heart block with a junctional escape rhythm. Electrocardiogram abnormalities abated within 24 hours of discontinuing antiretroviral therapy. The patient developed orthostatic symptoms after restarting nelfinavir. He was switched successfully to an efavirenz-based regimen. Subsequent administration of antiretroviral therapy containing ritonavir and indinavir with extended-release nifedipine resulted in recurrence of his orthostatic symptoms. Discontinuation of atenolol, and nifedipine dosage reduction by 50% were effective in managing his orthostatic changes. Careful monitoring by clinicians is necessary when concomitant administration of HIV protease inhibitors are prescribed with other agents that are metabolized through the cytochrome P450 system.
Subject(s)
Anti-HIV Agents/adverse effects , Antihypertensive Agents/adverse effects , HIV Protease Inhibitors/adverse effects , Hypotension, Orthostatic/chemically induced , Nifedipine/adverse effects , Alkynes , Anti-HIV Agents/therapeutic use , Antihypertensive Agents/administration & dosage , Antihypertensive Agents/therapeutic use , Benzoxazines , Cyclopropanes , Delayed-Action Preparations , Drug Interactions , HIV Protease Inhibitors/therapeutic use , Humans , Male , Middle Aged , Nelfinavir/adverse effects , Nelfinavir/therapeutic use , Nifedipine/administration & dosage , Nifedipine/therapeutic use , Oxazines/therapeutic use , Ritonavir/adverse effects , Ritonavir/therapeutic useABSTRACT
OBJECTIVE: To examine the use of low-dose ritonavir as a pharmacokinetic enhancer for HIV protease inhibitors. DATA SOURCES: Primary articles, review articles, and conference abstracts identified by MEDLINE search (1995-May 2001) and secondary sources. DATA SYNTHESIS: Low-dose ritonavir (100-200 mg) is increasingly being combined with HIV protease inhibitors to improve their effectiveness and allow less frequent dosing. An evaluation of the clinical evidence supporting this practice was conducted. CONCLUSIONS: Limited outcome data exist for low-dose ritonavir-based regimens in general. Although preliminary data appear promising, more clinical evidence is needed to determine the optimal dosing, long-term safety, and relative effectiveness of this approach. The role of these regimens in early therapy remains to be defined.
