ABP-ARA-1 is a preparation of arachidonic acid.  It is used for monitoring of Aspirin® and other cyclooxygenase inhibitors in routine platelet studies and indicates its effect on platelet function.  It may also be used in the differential diagnosis of Storage Pool Disease and Aspirin-like release defects.  As one would expect, it is sensitive to the action of Aspirin® and other cyclooxygenase inhibitors as well as to the action of glycoprotein (Gp) IIb/IIIa receptor antagonists and/or a deficiency of GpIIb/IIIa receptors.  It is insensitive to P2Y12 inhibitors such as clopidigrel.

ABP-ARA-1 is supplied as three separate vials, each containing 2.5 mg of lyophilized sodium arachadonate.  When reconstituted in 500 µL of purified water, the resultant stock solution is 5 mg/mL.  Reconstituted arachidonic acid is stable for 24 hours when stored at 2oC to 8oC and for up to eight weeks when stored at -20oC.   Prior to reconstitution or use, the reagent should be brought to room temperature.

Platelets are activated by arachidonic acid, which is converted by the platelet cyclooxygenase enzyme (COX-1) to the potent platelet agonist thromboxane A2 (TXA2).  Arachidonic acid alone is not a platelet agonist and is the physiological substrate of the platelet COX-1. Therefore, platelet activation using ABP-ARA-1 allows a very sensitive and specific detection of Aspirin® action.