Clopidogrel

Absorption

A 75mg oral dose of clopidogrel is 50% absorbed from the intestine. Clopidogrel can be taken with or without food. A meal decreases the AUC of the active metabolite by 57%. The active metabolite of clopidogrel reaches a maximum concentration after 30-60 minutes. Clopidogrel reached a Cmax of 2.04±2.0ng/mL in 1.40±1.07h.
The AUC for a 300mg oral dose of clopidogrel was 45.1±16.2ng*h/mL for poor metabolizers, 65.6±19.1ng*h/mL for intermediate metabolizers, and 104.3±57.3ng*h/mL for extensive metabolizers. The Cmax was 31.3±13ng/mL for poor metabolizers, 43.9±14ng/mL for intermediate metabolizers, and 60.8±34.3ng/mL for extensive metabolizers.

Toxicity

A single dose of clopidogrel at 1500-2000mg/kg was lethal to mice and rats while 3000mg/kg was lethal to baboons. Symptoms of overdose include vomiting, breathing difficulty, gastrointestinal hemorrhage, and prostration. Clopidogrel is irreversibly bound to platelets for their lifetime, which is approximately 11 days. Overdoses of clopidogrel can be treated with platelet transfusions to restore clotting ability.

Description

Clopidogrel was launched in the US as a potent inhibitor of platelet aggregation for the preventive management of secondary ischemic events, including MI, stroke and vascular deaths. Clopidogrel can be synthesized in 4 steps (including an optical resolution to the S active enantiomer) from 2-(2- ch1orophenyl)-glycine, the key step being the cyclization to thienopyridine with formaldehyde and acetic acid. Clopidogrel belongs to the original chemical class of Ticlopidine, but shows fewer side effects (in particular, bone-marrowsuppressing effects) at the dosage generally used. Like Ticlopidine, it is an Adenosine diphosphate (ADP) antagonist acting at the purinergic P2y receptor. In in vivo experiments with rabbits, Clopidogrel shows a maximal antiaggregant effect at 20mg/kg po, reducing adhesion of platelets to the vascular subendothelium ; moreover, it reduces myointimal thickening occuring after endothelial injury of rat carotid artery. Clopigrel does not affect platelet aggregation in vitro ; actually, its in vivo activity is highly dependent on hepatic metabolism. The results of a CAPRIE trial (Clopidogrel versus Aspirin in patients at risk of ischemic events) demonstrated that Clopidogrel was well tolerated and more effective than aspirin.

Description

Clopidogrel, sold under the brand name Plavix, is commonly known as a “blood thinner”. It prevents blood from clotting in patients who are vulnerable to stroke, heart attack, and other vascular diseases. Clopidogrel is actually a prodrug—its thiophene ring hydrolyzes in vivo to the active metabolite. An improved synthesis of the chiral α-amino ester moiety in clopidogrel was described in the?June 13, 2011, edition of Noteworthy Chemistry.

The Uses of Clopidogrel

anthelmintic, antiparasitic, antimite

Indications

Clopidogrel is indicated to reduce the risk of myocardial infarction for patients with non-ST elevated acute coronary syndrome (ACS), patients with ST-elevated myocardial infarction, and in recent MI, stroke, or established peripheral arterial disease,

Background

Clopidogrel is a prodrug of a platelet inhibitor used to reduce the risk of myocardial infarction and stroke. Clopidogrel is indicated to reduce the risk of myocardial infarction for patients with non-ST elevated acute coronary syndrome (ACS), patients with ST-elevated myocardial infarction, and in recent MI, stroke, or established peripheral arterial disease,
It has been shown to be superior to aspirin in reducing cardiovascular outcomes in patients with cardiovascular disease and provides additional benefit to patients with acute coronary syndromes already taking aspirin.
Clopidogrel was granted FDA approval on 17 November 1997.

Pharmacokinetics

Clopidogrel is a prodrug of a platelet inhibitor used to reduce the risk of myocardial infarction and stroke. It has a long duration of action as it is taken once daily and a large therapeutic window as it is given in doses of 75-300mg daily.

Metabolism

85-90% of an oral dose undergoes first pass metabolism by carboxylesterase 1 in the liver to an inactive carboxylic acid metabolite. about 2% of clopidogrel is oxidized to 2-oxoclopidogrel. This conversion is 35.8% by CYP1A2, 19.4% by CYP2B6, and 44.9% by CYP2C19 though other studies suggest CYP3A4, CYP3A5, and CYP2C9 also contribute. 2-oxoclopidogrel is further metabolized to the active metabolite. This conversion is 32.9% by CYP2B6, 6.79% by CYP2C9, 20.6% by CYP2C19, and 39.8% by CYP3A4.