Valdorin Mechanism of Action

Pharmacology: Pharmacodynamics: Mechanism of action: Clopidogrel is an inhibitor of platelet aggregation. A variety of drugs that inhibit platelet function have been shown to decrease morbid events in people with established atheroschlerotic cardiovascular disease as evidenced by stroke or transient ischemic attacks, myocardial infarction, or need for bypass or angioplasty. This indicates that platelets participate in the initiation and/or evolution of these events and that inhibiting them can reduce the event rate. The salicylates alleviate pain by virtue of both a peripheral and a central nervous system effect. Salicylates, by inhibiting the synthesis of prostaglandins that occur in inflamed tissues, prevent the sensitization of pain receptors to mechanical stimulation or to chemical such as bradykinin, that appear to mediate the pain response. Direct effects on the central nervous system have been described and suggest a hypothalamic site for the analgesic as well as the antipyretic effects.
Pharmacokinetics: Aspirin: Absorption after oral administration of a solution of aspirin is usually complete, while enteric-coated capsule are less reliably absorbed. Absorption of aspirin formulated as regular unbuffered capsules is intermediate between that of solution and of enteric-coated preparations and is usually greater than 80%. Presystemic metabolism of aspirin to salicylate results in little or no systemic availability of low oral doses, and is believed that aspirin in portal venous blood accounts for the effect of low doses on platelets. After 500 mg, peak plasma concentration of aspirin are achieved in about 14 minutes, while peak salicylic acid concentration are obtained at 0.5 to 1 h after dosing. The plasma half-life of aspirin is 15-20 min., salicylic acid exhibits dose-dependent kinetics, the apparent half-life after a 300 mg dose being around 3 h, after 1 g dose, around 5-6 h, after a 10 g dose around 20 h. The volume of distribution of aspirin is 0.15-0.21 kg^-1. Protein binding of aspirin occurs to an unknown but variable extent that is time as well as concentration dependent. Plasma albumin is acetylated by aspirin. Salicylates is also variably bound to plasma protein, the percentage bound decreasing with concentration. Salicylate penetrates into the breast milk, saliva, joint fluids, and cerebrospinal fluid, being detectable in concentration approximately 1.5 times those of blood in these fluids.
Fetal levels exceed concentration in maternal plasma.
Oral Absorption >80%.
Presystemic metabolism high.
Plasma half-life range 15-20 min.
(salicylate: 3-20 h).
Volume of distribution 0.21 kg^-1.
Plasma protein binding variable.