Thromboxane B2 is an inactive metabolite/product of thromboxane A2

Thromboxane A2

Thromboxane A2 is a thromboxane. It is produced by activated platelets and has prothrombotic properties: it stimulates activation of new platelets as well as increases platelet aggregation. This is achieved by mediating expression of the glycoprotein complex GP IIb/IIIa in the cell membrane of...

. It is almost completely cleared in the urine.

It itself is not involved in platelet activation and aggregation in case of a wound, but its precursor, thromboxane A2, is. Thromboxane A2 synthesis is the target of the drug aspirin

Aspirin

Aspirin , also known as acetylsalicylic acid , is a salicylate drug, often used as an analgesic to relieve minor aches and pains, as an antipyretic to reduce fever, and as an anti-inflammatory medication. It was discovered by Arthur Eichengrun, a chemist with the German company Bayer...

, which inhibits the COX-1 enzyme (the source of thromboxane A2 in platelets).