Extent of potential drug interactions among patients receiving anti-hypertensive medications

OBJECTIVE: To investigate the frequency of potential antihypertensive drug interactions among patients with cardiovascular diseases receiving antihypertensive medications. METHODS: The study took place in Nablus, Palestine starting April through October 2003. Patients with cardiovascular diseases (n=876) or who were receiving one or more antihypertensive medications were evaluated. All drugs prescribed for the patients were obtained from their medical files. A drug interaction database was developed based on updated Drug Interaction Facts to examine potential and level of drug interactions in each patient's regimen. Data were entered and analyzed using SPSS software. RESULTS: The number of "unique" pairs of potential drug interactions among the antihypertensive agents present in the data was 433. These included 16 cases (3.7%) level one; 34 cases (7.8%) level 2; 116 cases (26.8%) level 3; 136 cases (31.4%) level 4, and 131 (30.3%) level 5 interactions. Both increasing age and number of drugs were significantly associated with the potential for significant interactions at all levels with a p value less than 0.025. CONCLUSIONS: This study found a high frequency of potential drug interactions with agents typically used for hypertension. Similar investigations need to be carried out among patients with other types of chronic diseases. Drug interaction software might be necessary in governmental pharmacy departments.