INHIBITION OF PLATELET-AGGREGATION BY TRANSDERMAL GLYCERYL TRINITRATE

Objective-To determine the optimum conditions for the demonstration of an antiplatelet effect of nitric oxide and to use these conditions to elucidate the effects of a transdermal glyceryl trinitrate patch on p latelet aggregation in normal volunteers. Methods-An open prospective crossover study. The effects of nitric oxide on platelet aggregation i n whole blood and platelet rich plasma as stimulated by adenosine diph osphate and U46619 was assessed in the presence and absence of ilopros t and MB22948. Optimum conditions for the demonstration of an antiplat elet effect of nitric oxide were then applied to whole blood from norm al volunteers in the presence and absence of a transdermal glyceryl tr initrate patch. Setting-University hospital. Subjects-Eight normal vol unteers. Main outcome measures-Platelet aggregation in the presence an d absence of transdermal glyceryl trinitrate. Results-The optimum cond itions for the demonstration of an antiplatelet effect of nitric oxide in whole blood were collecting blood into a tube containing MB22948 a nd citrate and stimulating platelet aggregation with adenosine diphosp hate in the presence or absence of iloprost. Using this method a signi ficant effect of transdermal glyceryl trinitrate on platelet aggregati on was shown (P < 0.03) in the presence and absence of iloprost. Concl usions-These results are consistent with an inhibitory effect on plate let aggregation of nitric oxide liberated by transdermal glyceryl trin itrate. Optimum test conditions are needed to show this effect. The cl inical significance of the antiplatelet effect of transdermal glyceryl trinitrate is unknown.