Dipyridamole also inhibits phosphodiesterase and this can result in vasodilation. The effect of food on Aggrenox has not been studied. Aspirin undergoes hydrolysis to salicylic acid in the liver and gastrointestinal wall. Salicylic acid has a large volume of distribution and can be found in all tissues and fluids in the body. Dipyridamole achieves peak plasma levels approximately two hours after administration of the extended-release form.
Salicylate metabolism occurs primarily by hepatic microsomal enzymes.
These metabolic pathways are saturable and clearance decreases with increased serum concentrations. The half-life of the parent drug is about 20 minutes while the active salicylate can range from 3 to 10 hours depending upon the dose. Dipyridamole is metabolized by glucuronidation and concentrated mainly in the liver. The monoglucuronide metabolite has little activity. Elimination occurs in the feces via bile as glucuronide conjugates and unchanged drug.