Effient

Dosage Forms And Strengths

Effient 5-mg is available as a yellow, elongated hexagonal, film-coated, non-scored tablet debossed with “5121” on one side and 3 parallel arched lines followed by a “5” on the other side.

Effient 10-mg is available as a beige, elongated hexagonal, film-coated, non-scored tablet debossed with “5123” on one side and 3 parallel arched lines followed by a “10” on the other side.

Effient (prasugrel) is available as elongated hexagonal, film-coated, non-scored tablets in the following strengths, colors, imprints, and presentations:

Storage And Handling

Store at 25°C (77°F); excursions permitted to 15° to 30°C (59° to 86°F). Dispense and keep product in original container. Keep container closed and do not remove desiccant from bottle. Do not break the tablet.

Manufactured by Eli Lilly and Company, Indianapolis, IN, 46285, USAMarketed by Daiichi Sankyo, Inc. and Lilly USA, LLC. Revised: July 2016

Acute Coronary Syndrome

Effient® is indicated to reduce the rate of thrombotic cardiovascular (CV) events (including stent thrombosis) in patients with acute coronary syndrome (ACS) who are to be managed with percutaneous coronary intervention (PCI) as follows:

• Patients with unstable angina (UA) or non-ST-elevation myocardial infarction (NSTEMI).
• Patients with ST-elevation myocardial infarction (STEMI) when managed with primary or delayed PCI.

Effient has been shown to reduce the rate of a combined endpoint of cardiovascular death, nonfatal myocardial infarction (MI), or nonfatal stroke compared to clopidogrel. The difference between treatments was driven predominantly by MI, with no difference on strokes and little difference on CV death.

Initiate Effient 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. Effient may be administered with or without food .

Timing Of Loading Dose

In the clinical trial that established the efficacy and safety of Effient, the loading dose of Effient was not administered until coronary anatomy was established in UA/NSTEMI patients and in STEMI patients presenting more than 12 hours after symptom onset. In STEMI patients presenting within 12 hours of symptom onset, the loading dose of Effient was administered at the time of diagnosis, although most received Effient at the time of PCI. For the small fraction of patients that required urgent CABG after treatment with Effient, the risk of significant bleeding was substantial.

Although it is generally recommended that antiplatelet therapy be administered promptly in the management of ACS because many cardiovascular events occur within hours of initial presentation, in a trial of 4033 NSTEMI patients, no clear benefit was observed when Effient loading dose was administered prior to diagnostic coronary angiography compared to at the time of PCI; however, risk of bleeding was increased with early administration in patients undergoing PCI or early CABG.

Dosing In Low Weight Patients

Compared to patients weighing ≥ 60 kg, patients weighing < 60 kg have an increased exposure to the active metabolite of prasugrel and an increased risk of bleeding on a 10-mg once daily maintenance dose. Consider lowering the maintenance dose to 5-mg in patients < 60 kg. The effectiveness and safety of the 5-mg dose have not been prospectively studied.

Active Bleeding

Effient is contraindicated in patients with active pathological bleeding such as peptic ulcer or intracranial hemorrhage.

Prior Transient Ischemic Attack Or Stroke

Effient is contraindicated in patients with a history of prior transient ischemic attack (TIA) or stroke. In TRITONTIMI 38 (TRial to Assess Improvement in Therapeutic Outcomes by Optimizing Platelet InhibitioN with Prasugrel), patients with a history of TIA or ischemic stroke ( > 3 months prior to enrollment) had a higher rate of stroke on Effient (6.5%; of which 4.2% were thrombotic stroke and 2.3% were intracranial hemorrhage [ICH]) than on clopidogrel (1.2%; all thrombotic). In patients without such a history, the incidence of stroke was 0.9% (0.2% ICH) and 1.0% (0.3% ICH) with Effient and clopidogrel, respectively. Patients with a history of ischemic stroke within 3 months of screening and patients with a history of hemorrhagic stroke at any time were excluded from TRITON-TIMI 38. Patients who experience a stroke or TIA while on Effient generally should have therapy discontinued.

Hypersensitivity

Effient is contraindicated in patients with hypersensitivity (e.g., anaphylaxis) to prasugrel or any component of the product.

WARNINGS

Included as part of the PRECAUTIONS section.

PRECAUTIONS

General Risk Of Bleeding

Thienopyridines, including Effient, increase the risk of bleeding. With the dosing regimens used in TRITON-TIMI 38, TIMI (Thrombolysis in Myocardial Infarction) Major (clinically overt bleeding associated with a fall in hemoglobin ≥ 5 g/dL, or intracranial hemorrhage) and TIMI Minor (overt bleeding associated with a fall in hemoglobin of ≥ 3 g/dL but < 5 g/dL) bleeding events were more common on Effint than on clopidogrel. The bleeding risk is highest initially, as shown in Figure 1 (events through 450 days; inset shows events through 7 days).

Figure 1: Non-CABG-Related TIMI Major or Minor Bleeding Events.

Suspect bleeding in any patient who is hypotensive and has recently undergone coronary angiography, PCI,  CABG, or other surgical procedures even if the patient does not have overt signs of bleeding.

Do not use Effient in patients with active bleeding, prior TIA or stroke. Other risk factors for bleeding are:

• Age ≥ 75 years. Because of the risk of bleeding (including fatal bleeding) and uncertain effectiveness in patients ≥ 75 years of age, use of Effient is generally not recommended in these patients, except in high-risk situations (patients with diabetes or history of myocardial infarction) where its effect appears to be greater and its use may be considered.
• CABG or other surgical procedure.
• Body weight < 60 kg. Consider a lower (5-mg) maintenance dose.
• Propensity to bleed (e.g., recent trauma, recent surgery, recent or recurrent gastrointestinal (GI) bleeding, active peptic ulcer disease, severe hepatic impairment, or moderate to severe renal impairment).
• Medications that increase the risk of bleeding (e.g., oral anticoagulants, chronic use of non-steroidal anti-inflammatory drugs [NSAIDs], and fibrinolytic agents). Aspirin and heparin were commonly used in TRITONTIMI 38.

Thienopyridines inhibit platelet aggregation for the lifetime of the platelet (7-10 days), so withholding a dose will not be useful in managing a bleeding event or the risk of bleeding associated with an invasive procedure. Because the half-life of prasugrel's active metabolite is short relative to the lifetime of the platelet, it may be possible to restore hemostasis by administering exogenous platelets; however, platelet transfusions within 6 hours of the loading dose or 4 hours of the maintenance dose may be less effective.

Coronary Artery Bypass Graft Surgery-Related Bleeding

The risk of bleeding is increased in patients receiving Effient who undergo CABG. If possible, Effient should be discontinued at least 7 days prior to CABG.

Of the 437 patients who underwent CABG during TRITON-TIMI 38, the rates of CABG-related TIMI Major or Minor bleeding were 14.1% in the Effient group and 4.5% in the clopidogrel group. The higher risk for bleeding events in patients treated with Effient persisted up to 7 days from the most recent dose of study drug. For patients receiving a thienopyridine within 3 days prior to CABG, the frequencies of TIMI Major or Minor bleeding were 26.7% (12 of 45 patients) in the Effient group, compared with 5.0% (3 of 60 patients) in the clopidogrel group. For patients who received their last dose of thienopyridine within 4 to 7 days prior to CABG, the frequencies decreased to 11.3% (9 of 80 patients) in the prasugrel group and 3.4% (3 of 89 patients) in the clopidogrel group.

Do not start Effient in patients likely to undergo urgent CABG. CABG-related bleeding may be treated with transfusion of blood products, including packed red blood cells and platelets; however, platelet transfusions within 6 hours of the loading dose or 4 hours of the maintenance dose may be less effective.

Discontinuation Of Effient

Discontinue thienopyridines, including Effient, for active bleeding, elective surgery, stroke, or TIA. The optimal duration of thienopyridine therapy is unknown. In patients who are managed with PCI and stent placement, premature discontinuation of any antiplatelet medication, including thienopyridines, conveys an increased risk of stent thrombosis, myocardial infarction, and death. Patients who require premature discontinuation of a thienopyridine will be at increased risk for cardiac events. Lapses in therapy should be avoided, and if thienopyridines must be temporarily discontinued because of an adverse event(s), they should be restarted as soon as possible.

Thrombotic Thrombocytopenic Purpura

Thrombotic thrombocytopenic purpura (TTP) has been reported with the use of Effient. TTP can occur after a brief exposure ( < 2 weeks). TTP is a serious condition that can be fatal and requires urgent treatment, including plasmapheresis (plasma exchange). TTP is characterized by thrombocytopenia, microangiopathic hemolytic anemia (schistocytes [fragment red blood cells] seen on peripheral smear), neurological findings, renal dysfunction, and fever.

Hypersensitivity Including Angioedema

Hypersensitivity including angioedema has been reported in patients receiving Effient, including patients with a history of hypersensitivity reaction to other thienopyridines.

Patient Counseling Information

See FDA-approved patient labeling (Medication Guide)

Benefits and Risks

• Summarize the effectiveness features and potential side effects of Effient.
• Tell patients to take Effient exactly as prescribed.
• Remind patients not to discontinue Effient without first discussing it with the physician who prescribed Effient.
• Recommend that patients read the Medication Guide.

Bleeding

Inform patients that they:

• will bruise and bleed more easily.
• will take longer than usual to stop bleeding.
• should report any unanticipated, prolonged, or excessive bleeding, or blood in their stool or urine.

Other Signs and Symptoms Requiring Medical Attention

• Inform patients that TTP is a rare but serious condition that has been reported with Effient.
  • Instruct patients to get prompt medical attention if they experience any of the following symptoms that cannot otherwise be explained: fever, weakness, extreme skin paleness, purple skin patches, yellowing of the skin or eyes, or neurological changes.
• Inform patients that they may have hypersensitivity reactions including rash, angioedema, anaphylaxis, or other manifestations. Patients who have had hypersensitivity reactions to other thienopyridines may have hypersensitivity reactions to Effient.

Invasive Procedures

Instruct patients to:

• inform physicians and dentists that they are taking Effient before any invasive procedure is scheduled.
• tell the doctor performing the invasive procedure to talk to the prescribing health care professional before stopping Effient.

Concomitant Medications

Ask patients to list all prescription medications, over-the-counter medications, or dietary supplements they are taking or plan to take so the physician knows about other treatments that may affect bleeding risk (e.g., warfarin and NSAIDs).

Nonclinical Toxicology

Carcinogenesis, Mutagenesis, Impairment Of Fertility

Carcinogenesis

No compound-related tumors were observed in a 2-year rat study with prasugrel at oral doses up to 100 mg/kg/day ( > 100 times the recommended therapeutic exposures in humans [based on plasma exposures to the major circulating human metabolite]). There was an increased incidence of tumors (hepatocellular adenomas) in mice exposed for 2 years to high doses ( > 250 times the human metabolite exposure).

Mutagenesis

Prasugrel was not genotoxic in two in vitro tests (Ames bacterial gene mutation test, clastogenicity assay in Chinese hamster fibroblasts) and in one in vivo test (micronucleus test by intraperitoneal route in mice).

Impairment Of Fertility

Prasugrel had no effect on fertility of male and female rats at oral doses up to 300 mg/kg/day (80 times the human major metabolite exposure at daily dose of 10-mg prasugrel).

Use In Specific Populations

Pregnancy

Risk Summary

There are no data with Effient use in pregnant women to inform a drug-associated risk. No structural malformations were observed in animal reproductive and developmental toxicology studies when rats and rabbits were administered prasugrel during organogenesis at doses of up to 30 times the recommended therapeutic exposures in humans. Due to the mechanism of action of Effient, and the associated identified risk of bleeding, consider the benefits and risks of Effient and possible risks to the fetus when prescribing Effient to a pregnant woman.

The background risk of major birth defects and miscarriage for the indicated population is unknown. The background risk in the U.S. general population of major birth defects is 2-4% and of miscarriage is 15-20% of clinically recognized pregnancies.

Data

Animal Data

In embryo fetal developmental toxicology studies, pregnant rats and rabbits received prasugrel at maternally toxic oral doses equivalent to more than 40 times the human exposure. A slight decrease in fetal body weight was observed; but, there were no structural malformations in either species. In prenatal and postnatal rat studies, maternal treatment with prasugrel had no effect on the behavioral or reproductive development of the offspring at doses greater than 150 times the human exposure.

Lactation

Risk Summary

There is no information regarding the presence of prasugrel in human milk, the effects on the breastfed infant, or the effects on milk production. Metabolites of prasugrel were found in rat milk. The developmental and health benefits of breastfeeding should be considered along with the mother's clinical need for Effient and any potential adverse effects on the breastfed child from Effient or from the underlying maternal condition.

Data

Animal Data

Following a 5-mg/kg oral dose of [¹⁴C]-prasugrel to lactating rats, metabolites of prasugrel were detected in the maternal milk and blood.

Pediatric Use

Safety and effectiveness in pediatric patients have not been established. In a randomized, placebo-controlled trial, the primary objective of reducing the rate of vaso-occlusive crisis (painful crisis or acute chest syndrome) in pediatric patients, aged 2 to less than 18 years, with sickle cell anemia was not met.

Geriatric Use

In TRITON-TIMI 38, 38.5% of patients were ≥ 65 years of age and 13.2% were ≥ 75 years of age. The risk of bleeding increased with advancing age in both treatment groups, although the relative risk of bleeding (Effient compared with clopidogrel) was similar across age groups.

Patients ≥ 75 years of age who received Effient 10-mg had an increased risk of fatal bleeding events (1.0%) compared to patients who received clopidogrel (0.1%). In patients ≥ 75 years of age, symptomatic intracranial hemorrhage occurred in 7 patients (0.8%) who received Effient and in 3 patients (0.3%) who received clopidogrel. Because of the risk of bleeding, and because effectiveness is uncertain in patients ≥ 75 years of age , use of Effient is generally not recommended in these patients, except in high-risk situations (diabetes and past history of myocardial infarction) where its effect appears to be greater and its use may be considered.

Low Body Weight

In TRITON-TIMI 38, 4.6% of patients treated with Effient had body weight < 60 kg. Individuals with body weight < 60 kg had an increased risk of bleeding and an increased exposure to the active metabolite of prasugrel. Consider lowering the maintenance dose to 5-mg in patients < 60 kg. The effectiveness and safety of the 5-mg dose have not been prospectively studied.

Renal Impairment

No dosage adjustment is necessary for patients with renal impairment. There is limited experience in patients with end-stage renal disease, but such patients are generally at higher risk of bleeding.

Hepatic Impairment

No dosage adjustment is necessary in patients with mild to moderate hepatic impairment (Child-Pugh Class A and B). The pharmacokinetics and pharmacodynamics of prasugrel in patients with severe hepatic disease have not been studied, but such patients are generally at higher risk of bleeding.

Metabolic Status

In healthy subjects, patients with stable atherosclerosis, and patients with ACS receiving prasugrel, there was no relevant effect of genetic variation in CYP2B6, CYP2C9, CYP2C19, or CYP3A5 on the pharmacokinetics of prasugrel's active metabolite or its inhibition of platelet aggregation.

Potential for Other Drugs to Affect Prasugrel

Inhibitors of CYP3A - Ketoconazole (400 mg daily), a selective and potent inhibitor of CYP3A4 and CYP3A5, did not affect prasugrel-mediated inhibition of platelet aggregation or the active metabolite's AUC and Tmax, but decreased the Cmax by 34% to 46%. Therefore, CYP3A inhibitors such as verapamil, diltiazem, indinavir, ciprofloxacin, clarithromycin, and grapefruit juice are not expected to have a significant effect on the pharmacokinetics of the active metabolite of prasugrel.

Inducers of Cytochromes P450 - Rifampicin (600 mg daily), a potent inducer of CYP3A and CYP2B6 and an inducer of CYP2C9, CYP2C19, and CYP2C8, did not significantly change the pharmacokinetics of prasugrel's active metabolite or its inhibition of platelet aggregation. Therefore, known CYP3A inducers such as rifampicin, carbamazepine, and other inducers of cytochromes P450 are not expected to have significant effect on the pharmacokinetics of the active metabolite of prasugrel.

Drugs that Elevate Gastric pH - Daily coadministration of ranitidine (an H2 blocker) or lansoprazole (a proton pump inhibitor) decreased the Cmax of the prasugrel active metabolite by 14% and 29%, respectively, but did not change the active metabolite's AUC and Tmax. In TRITON-TIMI 38, Effient was administered without regard to coadministration of a proton pump inhibitor or H2 blocker.

Statins - Atorvastatin (80 mg daily), a drug metabolized by CYP450 3A4, did not alter the pharmacokinetics of prasugrel's active metabolite or its inhibition of platelet aggregation.

Heparin - A single intravenous dose of unfractionated heparin (100 U/kg) did not significantly alter coagulation or the prasugrel-mediated inhibition of platelet aggregation; however, bleeding time was increased compared with either drug alone.

Aspirin - Aspirin 150 mg daily did not alter prasugrel-mediated inhibition of platelet aggregation; however, bleeding time was increased compared with either drug alone.

Warfarin - A significant prolongation of the bleeding time was observed when prasugrel was coadministered with 15-mg of warfarin. Potential for Prasugrel to Affect Other Drugs

In vitro metabolism studies demonstrate that prasugrel's main circulating metabolites are not likely to cause clinically significant inhibition of CYP1A2, CYP2C9, CYP2C19, CYP2D6, or CYP3A, or induction of CYP1A2 or CYP3A.

Drugs Metabolized by CYP2B6 - Prasugrel is a weak inhibitor of CYP2B6. In healthy subjects, prasugrel decreased exposure to hydroxybupropion, a CYP2B6-mediated metabolite of bupropion, by 23%, an amount not considered clinically significant. Prasugrel is not anticipated to have significant effect on the pharmacokinetics of drugs that are primarily metabolized by CYP2B6, such as halothane, cyclophosphamide, propofol, and nevirapine.

Effect on Digoxin - The potential role of prasugrel as a Pgp substrate was not evaluated. Prasugrel is not an inhibitor of Pgp, as digoxin clearance was not affected by prasugrel coadministration.

Risk Summary

There are no data with Effient use in pregnant women to inform a drug-associated risk. No structural malformations were observed in animal reproductive and developmental toxicology studies when rats and rabbits were administered prasugrel during organogenesis at doses of up to 30 times the recommended therapeutic exposures in humans. Due to the mechanism of action of Effient, and the associated identified risk of bleeding, consider the benefits and risks of Effient and possible risks to the fetus when prescribing Effient to a pregnant woman.

The background risk of major birth defects and miscarriage for the indicated population is unknown. The background risk in the U.S. general population of major birth defects is 2-4% and of miscarriage is 15-20% of clinically recognized pregnancies.

Data

Animal Data

In embryo fetal developmental toxicology studies, pregnant rats and rabbits received prasugrel at maternally toxic oral doses equivalent to more than 40 times the human exposure. A slight decrease in fetal body weight was observed; but, there were no structural malformations in either species. In prenatal and postnatal rat studies, maternal treatment with prasugrel had no effect on the behavioral or reproductive development of the offspring at doses greater than 150 times the human exposure.

The following serious adverse reactions are also discussed elsewhere in the labeling:

• Bleeding
• Thrombotic Thrombocytopenic Purpura
• Hypersensitivity Including Angioedema

Clinical Trials Experience

Safety in patients with ACS undergoing PCI was evaluated in a clopidogrel-controlled study, TRITON-TIMI 38, in which 6741 patients were treated with Effient (60-mg loading dose and 10-mg once daily) for a median of 14.5 months (5802 patients were treated for over 6 months; 4136 patients were treated for more than 1 year). The population treated with Effient was 27 to 96 years of age, 25% female, and 92% Caucasian. All patients in the TRITON-TIMI 38 study were to receive aspirin. The dose of clopidogrel in this study was a 300-mg loading dose and 75-mg once daily.

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials cannot be directly compared with the rates observed in other clinical trials of another drug and may not reflect the rates observed in practice.

Drug Discontinuation

The rate of study drug discontinuation because of adverse reactions was 7.2% for Effient and 6.3% for clopidogrel. Bleeding was the most common adverse reaction leading to study drug discontinuation for both drugs (2.5% for Effient and 1.4% for clopidogrel). Bleeding

Bleeding

Unrelated to CABG Surgery - In TRITON-TIMI 38, overall rates of TIMI Major or Minor bleeding adverse reactions unrelated to coronary artery bypass graft surgery (CABG) were significantly higher on Effient than on clopidogrel, as shown in Table 1.

Table 1: Non-CABG-Related Bleeding^a (TRITON-TIMI 38)

Figure 1 demonstrates non-CABG related TIMI Major or Minor bleeding. The bleeding rate is highest initially, as shown in Figure 1 (inset: Days 0 to 7).

Bleeding by Weight and Age - In TRITON-TIMI 38, non-CABG-related TIMI Major or Minor bleeding rates in patients with the risk factors of age ≥ 75 years and weight < 60 kg are shown in Table 2.

Table 2: Bleeding Rates for Non-CABG-Related Bleeding by Weight and Age (TRITON-TIMI 38)

Bleeding Related to CABG - In TRITON-TIMI 38, 437 patients who received a thienopyridine underwent CABG during the course of the study. The rate of CABG-related TIMI Major or Minor bleeding was 14.1% for the Effient group and 4.5% in the clopidogrel group (see Table 3). The higher risk for bleeding adverse reactions in patients treated with Effient persisted up to 7 days from the most recent dose of study drug.

Table 3: CABG-Related Bleeding^a (TRITON-TIMI 38)

Bleeding Reported as Adverse Reactions - Hemorrhagic events reported as adverse reactions in TRITON-TIMI 38 were, for Effient and clopidogrel, respectively: epistaxis (6.2%, 3.3%), gastrointestinal hemorrhage (1.5%, 1.0%), hemoptysis (0.6%, 0.5%), subcutaneous hematoma (0.5%, 0.2%), post-procedural hemorrhage (0.5%, 0.2%), retroperitoneal hemorrhage (0.3%, 0.2%), pericardial effusion/hemorrhage/tamponade (0.3%, 0.2%), and retinal hemorrhage (0.0%, 0.1%).

Malignancies

During TRITON-TIMI 38, newly-diagnosed malignancies were reported in 1.6% and 1.2% of patients treated with prasugrel and clopidogrel, respectively. The sites contributing to the differences were primarily colon and lung. In another Phase 3 clinical study of ACS patients not undergoing PCI, in which data for malignancies were prospectively collected, newly-diagnosed malignancies were reported in 1.8% and 1.7% of patients treated with prasugrel and clopidogrel, respectively. The site of malignancies was balanced between treatment groups except for colorectal malignancies. The rates of colorectal malignancies were 0.3% prasugrel, 0.1% clopidogrel and most were detected during investigation of GI bleed or anemia. It is unclear if these observations are causally-related, are the result of increased detection because of bleeding, or are random occurrences.

Other Adverse Events

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%), abnormal hepatic function (0.22%, 0.27%), allergic reactions (0.36%, 0.36%), and angioedema (0.06%, 0.04%). Table 4 summarizes the adverse events reported by at least 2.5% of patients.

Table 4: Non-Hemorrhagic Treatment Emergent Adverse Events Reported by at Least 2.5% of Patients in Either Group

Postmarketing Experience

The following adverse reactions have been identified during post approval use of Effient. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.

Blood and lymphatic system disorders — Thrombocytopenia, Thrombotic thrombocytopenic purpura (TTP)

Immune system disorders — Hypersensitivity reactions including anaphylaxis

Signs And Symptoms

Platelet inhibition by prasugrel is rapid and irreversible, lasting for the life of the platelet, and is unlikely to be increased in the event of an overdose. In rats, lethality was observed after administration of 2000 mg/kg. Symptoms of acute toxicity in dogs included emesis, increased serum alkaline phosphatase, and hepatocellular atrophy. Symptoms of acute toxicity in rats included mydriasis, irregular respiration, decreased locomotor activity, ptosis, staggering gait, and lacrimation.

Recommendations About Specific Treatment

Platelet transfusion may restore clotting ability. The prasugrel active metabolite is not likely to be removed by dialysis.

Prasugrel produces inhibition of platelet aggregation to 20 μM or 5 μM ADP, as measured by light transmission aggregometry. Following a 60-mg loading dose of Effient, approximately 90% of patients had at least 50% inhibition of platelet aggregation by 1 hour. Maximum platelet inhibition was about 80% (see Figure 2). Mean steady-state inhibition of platelet aggregation was about 70% following 3 to 5 days of dosing at 10-mg daily after a 60-mg loading dose of Effient.

Figure 2: Inhibition (Mean±SD) of 20 μM ADP-induced Platelet Aggregation (IPA) Measured by Light Transmission Aggregometry after Prasugrel 60-mg.

Platelet aggregation gradually returns to baseline values over 5-9 days after discontinuation of prasugrel, this time course being a reflection of new platelet production rather than pharmacokinetics of prasugrel. Discontinuing clopidogrel 75-mg and initiating a prasugrel 10-mg maintenance dose with or without a prasugrel 60-mg loading dose results in a decrease of 14 percentage points in maximum platelet aggregation (MPA) by Day 7. This decrease in MPA is not greater than that typically produced by a 10-mg maintenance dose of prasugrel alone. The relationship between inhibition of platelet aggregation and clinical activity has not been established.

5-mg in Low Body Weight Patients - In patients with stable coronary artery disease, mean platelet inhibition in subjects < 60 kg taking 5-mg prasugrel was similar to that of subjects ≥ 60 kg taking 10-mg prasugrel. The relationship between inhibition of platelet aggregation and clinical activity has not been established.

Prasugrel is a prodrug and is rapidly metabolized to a pharmacologically active metabolite and inactive metabolites. The active metabolite has an elimination half-life of about 7 hours (range 2-15 hours). Healthy subjects, patients with stable atherosclerosis, and patients undergoing PCI show similar pharmacokinetics.

Absorption And Binding

Following oral administration, ≥ 79% of the dose is absorbed. The absorption and metabolism are rapid, with peak plasma concentrations (Cmax) of the active metabolite occurring approximately 30 minutes after dosing. The active metabolite's exposure (AUC) increases slightly more than proportionally over the dose range of 5 to 60-mg. Repeated daily doses of 10-mg do not lead to accumulation of the active metabolite. In a study of healthy subjects given a single 15-mg dose, the AUC of the active metabolite was unaffected by a high fat, high calorie meal, but Cmax was decreased by 49% and Tmax was increased from 0.5 to 1.5 hours. Effient can be administered without regard to food. The active metabolite is bound about 98% to human serum albumin.

Metabolism And Elimination

Prasugrel is not detected in plasma following oral administration. It is rapidly hydrolyzed in the intestine to a thiolactone, which is then converted to the active metabolite by a single step, primarily by CYP3A4 and CYP2B6 and to a lesser extent by CYP2C9 and CYP2C19. The estimates of apparent volume of distribution of prasugrel's active metabolite ranged from 44 to 68 L and the estimates of apparent clearance ranged from 112 to 166 L/hr in healthy subjects and patients with stable atherosclerosis. The active metabolite is metabolized to two inactive compounds by S-methylation or conjugation with cysteine. The major inactive metabolites are highly bound to human plasma proteins. Approximately 68% of the prasugrel dose is excreted in the urine and 27% in the feces as inactive metabolites.