Potential drug interactions with H₂-receptor antagonists in intensive care unit patients

This study's objectives were to identify the incidence of potential histamine-2 receptor antagonist drug interactions in a population of critically ill patients and to identify those at greatest risk for drug interactions. A literature review was completed to identify medications documented to interact when administered concomitantly with histamine-2 receptor antagonists. Data were prospectively collected on 277 consecutive patients admitted into the cardiac care units, medical intensive care units, and surgical intensive care units of two teaching hospitals. The mean age was 55 ± 16.4 years and one or more organ insufficiency was identified in 52.7% of patients. At least one potential drug interaction was found in 81.6%, with an average of 1.57 potential interactions occurring per patient. Cardiac care unit and medical intensive care unit patients had significantly more potential interactions with drugs having narrow therapeutic indices (P <0.03). Also, cardiac care unit patients received significantly more medications documented to interact with ranitidine alone or both cimetidine and ranitidine (P <0.003). Patients admitted to an intensive care unit and receiving a histamine-2 receptor antagonist may require more frequent monitoring because of the potential for drug interactions.