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.
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 Bleedinga (TRITON-TIMI 38) | Effient (%) (N=6741) | Clopidogrel (%) (N=6716) | p-value |
|---|
|
|
|
TIMI Major or Minor bleeding
|
4.5
|
3.4
|
p=0.002
|
|
TIMI Major bleedingb |
2.2
|
1.7
|
p=0.029
|
|
Life-threatening
|
1.3
|
0.8
|
p=0.015
|
|
Fatal
|
0.3
|
0.1
| |
|
Symptomatic intracranial hemorrhage (ICH)
|
0.3
|
0.3
| |
|
Requiring inotropes
|
0.3
|
0.1
| |
|
Requiring surgical intervention
|
0.3
|
0.3
| |
|
Requiring transfusion (≥4 units)
|
0.7
|
0.5
| |
|
TIMI Minor bleedingb |
2.4
|
1.9
|
p=0.022
|
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) [see Warnings and Precautions (5.1)].
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) | Major/Minor | Fatal |
|---|
Effient (%) | Clopidogrel (%) | Effient (%) | Clopidogrel (%) |
|---|
|
Weight < 60 kg (N=308 Effient, N=356 clopidogrel)
|
10.1
|
6.5
|
0.0
|
0.3
|
|
Weight ≥ 60 kg (N=6373 Effient, N=6299 clopidogrel)
|
4.2
|
3.3
|
0.3
|
0.1
|
|
Age < 75 years (N=5850 Effient, N=5822 clopidogrel)
|
3.8
|
2.9
|
0.2
|
0.1
|
|
Age ≥ 75 years (N=891 Effient, N=894 clopidogrel)
|
9.0
|
6.9
|
1.0
|
0.1
|
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 (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 Bleedinga (TRITON-TIMI 38) | Effient (%) (N=213) | Clopidogrel (%) (N=224) |
|---|
|
|
TIMI Major or Minor bleeding
|
14.1
|
4.5
|
|
TIMI Major bleeding
|
11.3
|
3.6
|
|
Fatal
|
0.9
|
0
|
|
Reoperation
|
3.8
|
0.5
|
|
Transfusion of ≥5 units
|
6.6
|
2.2
|
|
Intracranial hemorrhage
|
0
|
0
|
|
TIMI Minor bleeding
|
2.8
|
0.9
|
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. It is unclear if these observations are causally-related 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 |
Effient (%)
(N=6741)
|
Clopidogrel (%)
(N=6716)
|
|
Hypertension
|
7.5
|
7.1
|
|
Hypercholesterolemia/Hyperlipidemia
|
7.0
|
7.4
|
|
Headache
|
5.5
|
5.3
|
|
Back pain
|
5.0
|
4.5
|
|
Dyspnea
|
4.9
|
4.5
|
|
Nausea
|
4.6
|
4.3
|
|
Dizziness
|
4.1
|
4.6
|
|
Cough
|
3.9
|
4.1
|
|
Hypotension
|
3.9
|
3.8
|
|
Fatigue
|
3.7
|
4.8
|
|
Non-cardiac chest pain
|
3.1
|
3.5
|
|
Atrial fibrillation
|
2.9
|
3.1
|
|
Bradycardia
|
2.9
|
2.4
|
|
Leukopenia (< 4 x 109 WBC/L)
|
2.8
|
3.5
|
|
Rash
|
2.8
|
2.4
|
|
Pyrexia
|
2.7
|
2.2
|
|
Peripheral edema
|
2.7
|
3.0
|
|
Pain in extremity
|
2.6
|
2.6
|
|
Diarrhea
|
2.3
|
2.6
|
Blood and lymphatic system disorders - Thrombocytopenia, Thrombotic thrombocytopenic purpura (TTP) [see Warnings and Precautions (5.4) and Patient Counseling Information (17.3)]
Immune system disorders - Hypersensitivity reactions including anaphylaxis [see Contraindications (4.3)]
Pregnancy Category B - There are no adequate and well-controlled studies of Effient use in pregnant women. Reproductive and developmental toxicology studies in rats and rabbits at doses of up to 30 times the recommended therapeutic exposures in humans (based on plasma exposures to the major circulating human metabolite) revealed no evidence of fetal harm; however, animal studies are not always predictive of a human response. Effient should be used during pregnancy only if the potential benefit to the mother justifies the potential risk to the fetus.
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 pup 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 [see Nonclinical Toxicology (13.1)].
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.
Specific Populations
Pediatric - Pharmacokinetics and pharmacodynamics of prasugrel have not been evaluated in a pediatric population [see Use in Specific Populations (8.4)].
Geriatric - In a study of 32 healthy subjects between the ages of 20 and 80 years, age had no significant effect on pharmacokinetics of prasugrel's active metabolite or its inhibition of platelet aggregation. In TRITON-TIMI 38, the mean exposure (AUC) of the active metabolite was 19% higher in patients ≥75 years of age than in patients <75 years of age [see Warnings and Precautions (5.1), Adverse Reactions (6.1), and Use in Specific Populations (8.5)].
Body Weight - The mean exposure (AUC) to the active metabolite is approximately 30 to 40% higher in subjects with a body weight of <60 kg than in those weighing ≥60 kg [see Dosage and Administration (2), Warnings and Precautions (5.1), Adverse Reactions (6.1), and Use in Specific Populations (8.6)].
Gender - Pharmacokinetics of prasugrel's active metabolite are similar in men and women.
Ethnicity - Exposure in subjects of African and Hispanic descent is similar to that in Caucasians. In clinical pharmacology studies, after adjusting for body weight, the AUC of the active metabolite was approximately 19% higher in Chinese, Japanese, and Korean subjects than in Caucasian subjects.
Smoking - Pharmacokinetics of prasugrel's active metabolite are similar in smokers and nonsmokers.
Renal Impairment - Pharmacokinetics of prasugrel's active metabolite and its inhibition of platelet aggregation are similar in patients with moderate renal impairment (CrCL=30 to 50 mL/min) and healthy subjects. In patients with end stage renal disease, exposure to the active metabolite (both Cmax and AUC(0-tlast)) was about half that in healthy controls and patients with moderate renal impairment [see Use in Specific Populations (8.7)].
Hepatic Impairment - Pharmacokinetics of prasugrel's active metabolite and inhibition of platelet aggregation were similar in patients with mild to moderate hepatic impairment compared to healthy subjects. The pharmacokinetics and pharmacodynamics of prasugrel's active metabolite in patients with severe hepatic disease have not been studied [see Warnings and Precautions (5.1) and Use in Specific Populations (8.8)].
Drug Interactions
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 [see Drug Interactions (7.3)].
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 [see Drug Interactions (7.3)].
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 [see Drug Interactions (7.3)].
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 [see Drug Interactions (7.3)].
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 [see Drug Interactions (7.3)].
Aspirin - Aspirin 150 mg daily did not alter prasugrel-mediated inhibition of platelet aggregation; however, bleeding time was increased compared with either drug alone [see Drug Interactions (7.3)].
Warfarin - A significant prolongation of the bleeding time was observed when prasugrel was coadministered with 15 mg of warfarin [see Drug Interactions (7.1)].
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 [see Drug Interactions (7.3)].
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).
Literature Revised: December 6, 2010
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