WHEN TO TRY A NEW ANTIPLATELET DRUG FOR TIAs
"If a patient is on acetylsalicylic acid (ASA) 325 mg/day after a stroke or for transient ischemic attacks (TIA) and experiences further TIA-like symptoms, should the dose of ASA be increased or should a switch be made to another medication (i.e. clopidogrel)?" asks JAMES MORRISON, MD, of London, ON.
The dosage range for ASA as a stroke preventative agent ranges from 81 to 1,300 mg/day, depending on where you're practicing. It's been recognized that the higher the dose of ASA used, the more likely the patients are to experience side effects, especially gastrointestinal (GI) upset. The appearance of other antiplatelet agents, such as clopidogrel, and combination medications, such as dipyridamole/ ASA, offer additional choices. In some centres, recurrence of TIA or stroke while on enteric-coated ASA at a dose of 325 mg/day would be viewed as a "failure" of this medication, and the patient switched to clopidogrel or dipyridamole/ASA. In a few circumstances, though, one might wish to simply raise the dose of ASA, as in a patient with a previously documented allergy to one or more components of clopidogrel or dipyridamole/ASA. In the past, cost also sometimes encouraged the ongoing use of enteric-coated ASA rather than switching to the newer antiplatelet agents, but the difference isn't always so large today. LW