Abstract 5134: Distribution of Dipyridamole in Blood Components Among Post-Stroke Patients Treated With Extended Release Formulation
Background and Purpose - Extended release dipyridamole (ERD) is widely used in patients after ischemic stroke; however, the ability of this antithrombotic agent to be stored in different blood cells has never been explored in post-stroke patients. We hypothesized that since ERD is known to be highly lipophylic, the drug may be present not only in plasma, but also accumulated in platelets, leukocytes, and erythrocytes.
Methods - Fifteen patients after documented ischemic stroke were treated with Aggrenox (ERD and low dose aspirin combination) BID for 30 days, and 12 of them completed the study. ERD concentrations in blood cells and platelet poor plasma were measured by spectrofluorimetry at Baseline, Day 14, and Day 30 after the initiation of therapy.
Results - The background level of spectrofluorometry readings differs slightly among the blood components (132–211 ng/mL) due to the differences in the preparation of samples and cell isolation techniques. As expected, 2 weeks of ERD therapy produced steady state plasma concentration of dipyridamole already at Day 14 (1680±542ng/mL), followed by a slight not significant decrease at one month (1619±408). Two weeks of therapy was sufficient to achieve a consistent dipyridamole accumulation in erythrocytes (361±43), but not in platelets (244±78), or leukocytes (275±49). In fact, while blood cells continued dipyridamole intake beyond 14 days period, and this increase (398±66) was significant (p=0.02) at thirty days.
Conclusion - Treatment with ERD in post-stroke patients resulted not only in the achieving of therapeutic plasma dipyridamole concentrations, but also deposition of the drug in erythrocytes and leukocytes, but not in platelets. If confirmed, these data will affect our better understanding of dipyridamole pleiotropy, and may expand future clinical indications of ERD formulation.