Abstract
Our study carried out in elderly and multimorbid patients with acute coronary syndrome initially treated with ASS (100 mg per day) plus Clopidogrel (75 mg per day) was focused at Clopidogrel low- and non-responders and potential Clopidogrel-drug interactions. Moreover, we intended to clarify how far patients with reduced Clopidogrel response can profit by switching to Prasugrel.
In 178 patients (mean age: 74.1 ± 0.6 years) Thrombocyte Reactivity Indices (TRI) were measured by VASP-tests. Patients showing a limited Clopidogrel response (low- and non-responders) were switched to Prasugrel (60 mg loading dose followed by 5 or 10 mg maintenance dose per day; 10 mg as standard dose, 5 mg in patients aged 75 years or older or weighting 60 Kg or less). Patients who were switched to Prasugrel were controlled by further VASP-tests. Additional evaluations were made for several subgroups of different age and gender.
In elderly patients the fraction of Clopidogrel low- and non-responders tended to higher proportions than in younger patients (34.8 versus 46.8 %). In all cases with limited Clopidogrel response thrombocyte reactivity could be lowered by switching to Prasugrel. In patients of 75 years or older, or weighting less than 60 KG, a daily dose of 5 mg Prasugrel led to the same sufficient reduction of thrombocyte reactivity as in the other patients given 10 mg per day. After drug-switching circa 6 % remained low- or non responders regardless of whether they were treated with 5 or 10 mg Prasugrel. In patients successfully switched to Prasugrel we found the same reduction of thrombocyte reactivity as in Clopidogrel responders (mean TRI: 19%); all of our patients treated as described were free from any bleeding complications. Beside other drugs especially beta blockers seemed to be associated with significantly reduced Clopidogrel response, whereas proton pump inhibitors showed no interaction.
All in all, Prasugrel seems to be more effective in lowering thrombocyte reactivity also in elderly patients, because the proportion of patients with limited response is much lower than in patients treated with Clopidogrel.