Aspilets/Aspilets-EC Mechanism of Action

Pharmacology: Pharmacodynamics: Aspirin is a nonsteroidal anti-inflammatory agent. The antithrombotic activity of aspirin is due to its inhibitory effect on platelets which is mediated via irreversible acetylation of platelet cyclooxygenase with subsequent blockade of platelet thromboxane synthesis. The inhibitory effect of aspirin on platelet thromboxane production persists for the lifespan of the platelet, around 7 to 10 days. As a result, acetylation of platelet cyclooxygenase and consequent inhibition of thromboxane formation is cumulative on repeated dosing.
Low doses of aspirin inhibit platelet aggregation and may be more effective than higher doses. Larger doses inhibit cyclooxygenase in arterial walls, interfering with prostacyclin production, a potent vasodilator and inhibitor of platelet aggregation.
Pharmacokinetics: Aspirin is rapidly and widely distributed into most body tissues and fluids. Aspirin's volume of distribution is 0.15 to 0.2 L/kg. Aspirin is poorly bound to plasma proteins; the unhydrolyzed drug is 33% bound at a serum salicylate concentration of 120 mcg/mL.
Aspirin's elimination half-life is about 15 to 20 minutes. Unlike salicylate, unhydrolyzed aspirin does not undergo capacity-limited metabolism and does not accumulate in plasma after multiple doses. Aspirin is partially hydrolyzed to salicylate during absorption by esterases in the gastrointestinal mucosa after oral administration. After absorption, unhydrolyzed aspirin is rapidly and almost completely hydrolyzed by esterases principally in the liver but also in plasma, erythrocytes, and synovial fluid; hydrolysis occurs more slowly in synovial fluid since the amounts of esterases in synovial fluid are lower. Aspirin may be hydrolyzed more slowly in women since women apparently have lower amounts of plasma aspirin esterases. About 1% of an oral aspirin dose is excreted unhydrolyzed in urine. The remainder is excreted in urine as salicylate and its metabolites.
Aspilets: About 80 to 100% of an oral dose of aspirin is absorbed from the gastrointestinal tract. However, the actual bioavailability of the drug as unhydrolyzed aspirin is lower since aspirin is partially hydrolyzed to salicylate in the gastrointestinal mucosa during absorption and on first pass through the liver.
Food does not appear to decrease the bioavailability of unhydrolyzed aspirin; however, absorption is delayed and peak serum aspirin concentration may be decreased.
Aspilets-EC: Aspirin is rapidly absorbed from the gastrointestinal tract. After oral administration, absorption of non-ionized aspirin occurs in the stomach. Aspirin, in an acid-resistant coating, is not released in the stomach but in the alkaline environment of the intestine. Therefore, absorption of aspirin is delayed by 3 to 6 hours and time to achieve mean peak aspirin concentration is 4 to 6 hours after administration of the enteric-coated tablet.