Background The management of clopidogrel in hyper-responders has not been well described. We report the treatment and dose adjustment individualization with clopidogrel oral solution (COS) in hyper-responder patients with an unruptured intracranial aneurysm treated with a stent.

Methods A prospective study (2015–2018) in patients receiving clopidogrel prior to endovascular treatment was performed. Platelet reactivity after clopidogrel therapy was evaluated with the VerifyNow PRU test. Initial values ≤80 PRU (P2Y12 reactivity units) were classified as a hyper-response according to prior evidence. Patients were treated with clopidogrel for 7–10 days before stent treatment. Seven days post-procedure the dose of COS was gradually reduced (30 mg–20 mg–10 mg–5 mg) every 5 days to 5 mg (1 mL)/day.

Results Twenty patients with 24 aneurysms were classified as having a hyper-response to clopidogrel. Mean age was 55.2 years (range 42–64) and 80% were women. Mean baseline PRU value and the percentage of platelet inhibition were 16.4±11.5 PRU and 92.05±7.5%, respectively. The mean time used to decrease the dose of clopidogrel to 5 mg/day was 27±4.3 days. Modified dosing strategies were shown to increase the final PRU values and to decrease the percentage of platelet inhibition (137.42±27.4 and 41.5±14.8%, respectively). Two of the 20 patients with dose adjustment of oral solution of clopidogrel (5 mg/day) in our cohort exhibited a delayed conversion to hypo-response. No patients suffered thromboembolic events related to the dose adjustment of clopidogrel with 5 mg/day during the follow-up.

Conclusion Reduction of the daily maintenance dose of clopidogrel in hyper-responder patients could provide a similar antiplatelet effect to the standard dose of clopidogrel, allowing a PRU value in the optimal range.