Administration and dosage
Initiate Effient (the brand name of prasugrel) treatment as a single 60 mg oral loading dose and then continue at 10 mg orally once daily. Patients taking Effient should also take aspirin (75 mg to 325 mg) daily.
Prasugrel is not detected in plasma following oral administration. It is rapidly hydrolyzed in the intestine to thiolactone by human carboxylesterase (hCE) 2. This intermediate is further metabolized to its active metabolite, R-138727, in a single step by cytochrome P450 enzymes in the liver (primarily CYP3A4 and CYP2B6 and to a lesser extent by CYP2C9 and CYP2C19). The active metabolite is further metabolized by S-methylation or cysteine conjugation to two inactive metabolites. Unlike clopidogrel, transformation of prasugrel to its active metabolite does not appear to be affected by cytochrome P450 polymorphisms.
Prasugrel is a member of the thienopyridine class of ADP receptor inhibitors, like ticlopidine (trade name Ticlid) and clopidogrel (trade name Plavix). These agents reduce the aggregation ("clumping") of platelets by irreversibly binding to P2Y12 receptors. Compared to clopidogrel, prasugrel inhibits adenosine diphosphate–induced platelet aggregation more rapidly, more consistently, and to a greater extent than do standard and higher doses of clopidogrel in healthy volunteers and in patients with coronary artery disease, including those undergoing PCI. The increased potency of prasugrel appears to be due to more efficient conversion to its active metabolite. However, it carries a higher risk of bleed compared to clopidogrel, which may be a result of its higher potency. Prasugrel produces inhibition of platelet aggregation to 20 μM or 5 μM ADP, as measured by light transmission aggregometry.
Prasugrel is used in combination with low dose aspirin to prevent thrombosis in patients with acute coronary syndrome (ACS), including unstable angina pectoris, non-ST elevation myocardial infarction (NSTEMI), and ST elevation myocardial infarction (STEMI), who are planned for treatment with percutaneous coronary intervention (PCI). In studies, prasugrel was more effective than the related clopidogrel but also caused more bleeding. Overall mortality was the same.
Prasugrel does not change the risk of death when given to people who have had a STEMI or NSTEMI. Prasugrel does however increase the risk of bleeding and may decrease the risk of further cardiovascular problems. Thus routine use in NSTEMI patients is of questionable value.
Prasugrel (brand name: “efficient”), a thienopyridine derivative, is a platelet activation and aggregation inhibitor structurally and pharmacologically related to clopidogrel and ticlopidine. Similar to clopidogrel, prasugrel is a prodrug that requires enzymatic transformation in the liver to its active metabolite, R-138727. R-138727 irreversibly binds to P2Y12 type ADP receptors on platelets thus preventing activation of the GPIIb/IIIa receptor complex. As a result, inhibition of ADP-mediated platelet activation and aggregation occurs. Prasugrel was developed by Daiichi Sankyo Co. and is currently marketed in the United States and Canada in cooperation with Eli Lilly and Company for acute coronary syndromes planned for percutaneous coronary intervention (PCI). FDA approved in 2009. Its brand name is “efficient”.
Figure 1 Molecular structure of Prasugrel;
Mode of action
Prasugrel is an inhibitor of platelet activation and aggregation through the irreversible binding of its active metabolite to the P2Y12 class of ADP receptors on platelets.
Inhibits platelet aggregation
(platelet ADPP 2Y12 antagonist).
Warning and precaution
CABG-related bleeding: Risk increases in patients receiving Effient who undergo CABG.
Discontinuation of Effient: Premature discontinuation increases risk of stent thrombosis, MI, and death.
Thrombotic thrombocytopenic purpura (TTP): TTP has been reported with Effient.
Prasugrel should not be given to patients with active pathological bleeding, such as peptic ulcer or a history of transient ischemic attack or stroke, because of higher risk of stroke (thrombotic stroke and intracranial hemorrhage).
Co-administration of Effient and warfarin increases the risk of bleeding.
Non-Steroidal Anti-Inflammatory Drugs
Co-administration of Effient and NSAIDs (used chronically) may increase the risk of bleeding.
Other Concomitant Medications
Effient can be administered with drugs that are inducers or inhibitors of cytochrome P450 enzymes. Effient can be administered with aspirin (75 mg to 325 mg per day), heparin, GPIIb/IIIa inhibitors, statins, digoxin, and drugs that elevate gastric pH, including proton pump inhibitors and H2 blockers.
Common adverse reactions include Bleeding, thrombotic Thrombocytopenic Purpura and Hypersensitivity Including Angioedema.
In TRITON-TIMI 38, common and other important non-hemorrhagic adverse events were, for Effient and clopidogrel, respectively: severe thrombocytopenia (0.06%, 0.04%), anemia (2.2%, 2.0%), and abnormal hepatic function (0.22%, 0.27%), and allergic reactions (0.36%, 0.36%), and angioedema (0.06%, 0.04%).
Prasugrel is usually formulated in the form of hydrochloride salt. Prasugrel hydrochloride has the empirical formula C20H20FNO3S•HCl representing a molecular weight of 409.90. Prasugrel hydrochloride is a white to practically white solid. It is soluble at pH 2, slightly soluble at pH 3 to 4, and practically insoluble at pH 6 to 7.5. It also dissolves freely in methanol and is slightly soluble in 1-and 2-propanol and acetone. It is practically insoluble in diethyl ether and ethyl acetate.