Pharmacological Study That Measures Omeprazole Effect on Aspirins Absorption in Healthy Volunteers

Aspirin is a weak acid that crosses the gastric and intestinal mucosa by passive diffusion while in its lipophilic nature.Omeprazole, a proton pump inhibitor, inhibits gastric acid secretion. We assumed that omeprazole inhibits aspirin absorption, thus reducing its action on platelets. healthy volunteers, with no known peptic disease or bleeding disorders will be enrolled. All volunteers will receive 7 days of Aspirin (100mg) alone, followed by 14 days of Aspirin and Omeprazole 20mg twice daily for 3 days and then 20mg once daily. Blood levels of Aspirin will be determined by High performance liquid chromatography (HPLC), 0, 1, 2, 4, 6, 10, 24 hours after the administration of Aspirin alone on day 7 and Aspirin plus Omeprazole on day 21. Platelet function tests will be determined by platelet-rich plasma aggregometry in response to Arachidonic acid (500mg/ml), Ristocetin (1.5mg/ml) and Adenosine 5'-diphosphate (20mM) on day 0 as baseline and on day 7 and 21 of the study.