Clopidogrel-associated leukopenia.

Objective: To report a case of leukopenia in a patient receiving clopidogrel following intracoronary stent placement.

Case Summary: A 58-year-old white man presented to the emergency department (ED) with fever and chills. Seven days prior to presentation, he underwent intracoronary stent placement and clopidogrel 75 mg once daily was initiated. In the ED, laboratory evaluation revealed leukopenia with negative blood and urine cultures. The patient was released but returned the following day with fever and sweating. Infectious complications were ruled out, and clopidogrel was discontinued. Leukopenia resolved within 7 days, and the patient has experienced no further hematologic complications. Based on the Naranjo probability scale, the leukopenia was rated as a probable reaction to clopidogrel.

Discussion: Ticlopidine and clopidogrel are the 2 commercially available thienopyridine antiplatelet agents. Risk of myelotoxicity with ticlopidine is well known and requires frequent hematologic monitoring. Clopidogrel is better tolerated, less toxic, and has more extensive indications, including use in acute coronary syndrome. These factors have resulted in the replacement of ticlopidine by clopidogrel. The 4 previously published reports of clopidogrel-associated white blood cell (WBC) toxicity are described. The mechanism of myelotoxicity with clopidogrel is not known.

Conclusions: Better tolerability, reduced toxicity (particularly hematologic), and the convenience of once-daily dosing have resulted in the replacement of ticlopidine with clopidogrel. WBC toxicity associated with clopidogrel therapy is very infrequent and has occurred weeks to months following therapy initiation. Clinicians should be aware of the potential for this adverse effect.