Q: 34 year old male with history of HIV on anti-retroviral therapy is admitted to ICU with shortness of breath. There is a concern for right heart failure on ECHO. Pulmonary artery catheter is floated. Patient is found to have moderate to severe pulmonary hypertension. Decision is made to add sildenafil in treatment plan. What precaution should be taken?  

Answer: Patients with HIV are usually on protease inhibitors for their maintenance therapy. Protease inhibitors inhibit the metabolism of sildenafil, increasing the chances of side effects many folds. Recommendation for patients on protease inhibitors to use sildenafil is no more than 25 mg every 48 hours.