Aspirin And Extended - Release Dipyridamole

1 INDICATIONS AND USAGE Aspirin and Extended-Release Dipyridamole Capsule is indicated to reduce the risk of stroke in patients who have had transient ischemia of the brain or completed ischemic stroke due to thrombosis. Aspirin and Extended-Release Dipyridamole Capsule is a combination of aspirin and dipyridamole, antiplatelet agents, indicated to reduce the risk of stroke in patients who have had transient ischemia of the brain or completed ischemic stroke due to thrombosis ( 1 )

2 DOSAGE AND ADMINISTRATION Aspirin and Extended-Release Dipyridamole Capsules are not interchangeable with the individual components of aspirin and dipyridamole tablets. The recommended dose of Aspirin and Extended-Release Dipyridamole Capsules is one capsule given orally twice daily, one in the morning and one in the evening. Swallow capsules whole without chewing. Aspirin and Extended-Release Dipyridamole Capsules can be administered with or without food. One capsule twice daily (morning and evening) with or without food ( 2 ) In case of intolerable headaches during initial treatment, switch to one capsule at bedtime and low-dose aspirin in the morning; resume BID dosing within one week ( 2.1 ) Do not chew capsule ( 2 ) Not interchangeable with the individual components of aspirin and dipyridamole tablets ( 2 ) Dispense in this unit-of-use container ( 16 ) 2.1 Alternative Regimen in Case of Intolerable Headaches In the event of intolerable headaches during initial treatment, switch to one capsule at bedtime and low-dose aspirin in the morning. Because there are no outcome data with this regimen and headaches become less of a problem as treatment continues, patients should return to the usual regimen as soon as possible, usually within one week.

6 ADVERSE REACTIONS The following adverse reactions are discussed elsewhere in the labeling: Hypersensitivity [see Contraindications ( 4.1 ) ] Allergy [see Contraindications ( 4.2 ) ] Risk of Bleeding [see Warnings and Precautions ( 5.1 )] The most frequently reported adverse reactions (>10% and greater than placebo) were headache, dyspepsia, abdominal pain, nausea, and diarrhea ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Endo at 1-800-828-9393 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. The efficacy and safety of aspirin and extended-release dipyridamole was established in the European Stroke Prevention Study-2 (ESPS2). ESPS2 was a double-blind, placebo-controlled study that evaluated 6602 patients over the age of 18 years who had a previous ischemic stroke or transient ischemic attack within ninety days prior to entry. Patients were randomized to either aspirin and extended-release dipyridamole, aspirin, ER-DP, or placebo [see Clinical Studies ( 14 )] ; primary endpoints included stroke (fatal or nonfatal) and death from all causes. This 24-month, multicenter, double-blind, randomized study (ESPS2) was conducted to compare the efficacy and safety of aspirin and extended-release dipyridamole with placebo, extended-release dipyridamole alone and aspirin alone. The study was conducted in a total of 6602 male and female patients who had experienced a previous ischemic stroke or transient ischemia of the brain within three months prior to randomization. Table 1 presents the annualized event rate for adverse events that occurred in 1%/year or more of patients treated with aspirin and extended-release dipyridamole where the incidence was also at least 1%/year greater than in those patients treated with placebo. There is no clear benefit of the dipyridamole/aspirin combination over aspirin with respect to safety. Table 1 Incidence of Adverse Events in ESPS2 a Individual Treatment Group Body System/Preferred Term Aspirin and Extended-Release Dipyridamole n (%/year) b ER-DP Alone n (%/year) b ASA Alone n (%/year) b Placebo n (%/year) b Total Number of Patients 1,650 1,654 1,649 1,649 Central and Peripheral Nervous System Disorders Headache 647 (28.25) 634 (27.91) 558 (22.10) 543 (22.29) Gastrointestinal System Disorders Dyspepsia 303 (13.23) 288 (12.68) 299 (11.84) 275 (11.29) Abdominal Pain 289 (12.62) 255 (11.22) 262 (10.38) 239 (9.81) Nausea 264 (11.53) 254 (11.18) 210 (8.32) 232 (9.53) Diarrhea 210 (9.17) 257 (11.31) 112 (4.44) 161 (6.61) Vomiting 138 (6.03) 129 (5.68) 101 (4.00) 118 (4.84) Platelet, Bleeding and Clotting Disorders Hemorrhage NOS 52 (2.27) 24 (1.06) 46 (1.82) 24 (0.99) a Reported by ≥1%/year of patients during aspirin and extended-release dipyridamole treatment where the incidence was at least 1%/year greater than in those treated with placebo. b Annual event rate per 100 pt-years = 100* number of subjects with event/subject-years. Subject-years is defined as cumulative number of days on treatment divided by 365.25. Note: ER-DP = extended-release dipyridamole 200 mg; ASA = aspirin 25 mg. The dosage regimen for all treatment groups is BID. NOS = not otherwise specified. Discontinuation due to adverse events in ESPS2 was 25% for aspirin and extended-release dipyridamole, 25% for extended-release dipyridamole, 19% for aspirin, and 21% for placebo (refer to Table 2). Table 2 Incidence of Adverse Events that Led to the Discontinuation of Treatment a Treatment Groups Aspirin and Extended-Release Dipyridamole n (%/year) b ER-DP n (%/year) b ASA n (%/year) b Placebo n (%/year) b Total Number of Patients 1,650 1,654 1,649 1,649 Patients with at least one Adverse Event that led to treatment discontinuation 417 (18.21) 419 (18.44) 318 (12.59) 352 (14.45) Headache 165 (7.20) 166 (7.31) 57 (2.26) 69 (2.83) Nausea 91 (3.97) 95 (4.18) 51 (2.02) 53 (2.18) Abdominal Pain 74 (3.23) 64 (2.82) 56 (2.22) 52 (2.13) Vomiting 53 (2.31) 52 (2.29) 28 (1.11) 24 (0.99) a Reported by ≥1%/year of patients during aspirin and extended-release dipyridamole treatment where the incidence was at least 1%/year greater than in those treated with placebo. b Annual event rate per 100 pt-years = 100* number of subjects with event/subject-years. Subject-years is defined as cumulative number of days on treatment divided by 365.25. Note: ER-DP = extended-release dipyridamole 200 mg; ASA = aspirin 25 mg. The dosage regimen for all treatment groups is BID. Headache was most notable in the first month of treatment. 6.2 Post Marketing Experience The following is a list of additional adverse reactions that have been reported either in the literature or are from post-marketing spontaneous reports for either dipyridamole or aspirin. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to estimate reliably their frequency or establish a causal relationship to drug exposure. Decisions to include these reactions in labeling are typically based on one or more of the following factors: (1) seriousness of the reaction, (2) frequency of reporting, or (3) strength of causal connection to aspirin and extended-release dipyridamole. Body as a Whole: Hypothermia, chest pain, allergic reaction, syncope Cardiovascular: Angina pectoris, hypotension Central Nervous System: Cerebral edema, dizziness, cerebral hemorrhage, intracranial hemorrhage, subarachnoid hemorrhage Fluid and Electrolyte: Hyperkalemia, metabolic acidosis, respiratory alkalosis, hypokalemia Gastrointestinal: Pancreatitis, Reye syndrome, hematemesis, gastritis, ulceration and perforation, hemorrhage rectum, melena, GI hemorrhage Hearing and Vestibular Disorders: Hearing loss Heart Rate and Rhythm Disorders: Tachycardia, palpitation Immune System Disorders: Hypersensitivity, acute anaphylaxis, laryngeal edema Liver and Biliary System Disorders: Hepatitis, hepatic failure, cholelithiasis, jaundice, hepatic function abnormal Musculoskeletal : Rhabdomyolysis, myalgia Metabolic and Nutritional Disorders: Hypoglycemia, dehydration Platelet, Bleeding and Clotting Disorders: Prolongation of the prothrombin time, disseminated intravascular coagulation, coagulopathy, thrombocytopenia, hematoma, gingival bleeding, epistaxis, purpura Psychiatric Disorders: Confusion, agitation Respiratory: Tachypnea, dyspnea, hemoptysis Skin and Appendages Disorders: Rash, alopecia, angioedema, Stevens-Johnson syndrome, skin hemorrhages such as bruising, ecchymosis, and hematoma, pruritus, urticaria, and drug reaction with eosinophilia and systemic symptoms (DRESS) Urogenital: Interstitial nephritis, papillary necrosis, proteinuria, renal insufficiency and failure, hematuria Vascular (Extracardiac) Disorders: Allergic vasculitis, flushing Other Adverse Events: Anorexia, aplastic anemia, migraine, pancytopenia, thrombocytosis.

12.3 Pharmacokinetics There are no significant interactions between aspirin and dipyridamole. The kinetics of the components are unchanged by their co-administration as aspirin and extended-release dipyridamole. Absorption Dipyridamole: Peak plasma levels of dipyridamole are achieved 2 hours (range 1 to 6 hours) after administration of a daily dose of 400 mg aspirin and extended-release dipyridamole (given as 200 mg BID). The peak plasma concentration at steady-state is 1.98 mcg/mL (1.01 to 3.99 mcg/mL) and the steady-state trough concentration is 0.53 mcg/mL (0.18 to 1.01 mcg/mL). Aspirin: Peak plasma levels of aspirin are achieved 0.63 hours (0.5 to 1 hour) after administration of a 50 mg aspirin daily dose from aspirin and extended-release dipyridamole (given as 25 mg BID). The peak plasma concentration at steady-state is 319 ng/mL (175 to 463 ng/mL). Aspirin undergoes moderate hydrolysis to salicylic acid in the liver and the gastrointestinal wall, with 50% to 75% of an administered dose reaching the systemic circulation as intact aspirin. Effect of Food Dipyridamole: When aspirin and extended-release dipyridamole capsules were taken with a high fat meal, dipyridamole peak plasma levels (C max ) and total absorption (AUC) were decreased at steady-state by 20 to 30% compared to fasting. Due to the similar degree of inhibition of adenosine uptake at these plasma concentrations, this food effect is not considered clinically relevant. Aspirin: When aspirin and extended-release dipyridamole capsules were taken with a high fat meal, there was no difference for aspirin in AUC at steady-state, and the approximately 50% decrease in C max was not considered clinically relevant based on a similar degree of cyclooxygenase inhibition comparing the fed and fasted state. Distribution Dipyridamole: Dipyridamole is highly lipophilic (log P=3.71, pH=7); however, it has been shown that the drug does not cross the blood-brain barrier to any significant extent in animals. The steady-state volume of distribution of dipyridamole is about 92 L. Approximately 99% of dipyridamole is bound to plasma proteins, predominantly to alpha 1-acid glycoprotein and albumin. Aspirin: Aspirin is poorly bound to plasma proteins and its apparent volume of distribution is low (10 L). Its metabolite, salicylic acid, is highly bound to plasma proteins, but its binding is concentration-dependent (nonlinear). At low concentrations (<100 mcg/mL), approximately 90% of salicylic acid is bound to albumin. Salicylic acid is widely distributed to all tissues and fluids in the body, including the central nervous system, breast milk, and fetal tissues. Early signs of salicylate overdose (salicylism), including tinnitus (ringing in the ears), occur at plasma concentrations approximating 200 mcg/mL [see Overdosage ( 10 )] . Metabolism and Elimination Dipyridamole: Dipyridamole is metabolized in the liver, primarily by conjugation with glucuronic acid, of which monoglucuronide which has low pharmacodynamic activity is the primary metabolite. In plasma, about 80% of the total amount is present as parent compound and 20% as monoglucuronide. Most of the glucuronide metabolite (about 95%) is excreted via bile into the feces, with some evidence of enterohepatic circulation. Renal excretion of parent compound is negligible and urinary excretion of the glucuronide metabolite is low (about 5%). With intravenous (i.v.) treatment of dipyridamole, a triphasic profile is obtained: a rapid alpha phase, with a half-life of about 3.4 minutes, a beta phase, with a half-life of about 39 minutes, (which, together with the alpha phase accounts for about 70% of the total area under the curve, AUC) and a prolonged elimination phase λ z with a half-life of about 15.5 hours. Because of the extended absorption phase of the dipyridamole component, only the terminal phase is apparent from oral treatment with aspirin and extended-release dipyridamole which was 13.6 hours. Aspirin: Aspirin is rapidly hydrolyzed in plasma to salicylic acid, with a half-life of 20 minutes. Plasma levels of aspirin are essentially undetectable 2 to 2.5 hours after dosing and peak salicylic acid concentrations occur 1 hour (range: 0.5 to 2 hours) after administration of aspirin. Salicylic acid is primarily conjugated in the liver to form salicyluric acid, a phenolic glucuronide, an acyl glucuronide, and a number of minor metabolites. Salicylate metabolism is saturable and total body clearance decreases at higher serum concentrations due to the limited ability of the liver to form both salicyluric acid and phenolic glucuronide. Following toxic doses (10 to 20 g), the plasma half-life may be increased to over 20 hours. The elimination of acetylsalicylic acid follows first-order kinetics with aspirin and extended-release dipyridamole and has a half-life of 0.33 hours. The half-life of salicylic acid is 1.71 hours. Both values correspond well with data from the literature at lower doses which state a resultant half-life of approximately 2 to 3 hours. At higher doses, the elimination of salicylic acid follows zero-order kinetics (i.e., the rate of elimination is constant in relation to plasma concentration), with an apparent half-life of 6 hours or higher. Renal excretion of unchanged drug depends upon urinary pH. As urinary pH rises above 6.5, the renal clearance of free salicylate increases from <5% to >80%. Alkalinization of the urine is a key concept in the management of salicylate overdose [see Overdosage ( 10 )] . Following therapeutic doses, about 10% is excreted as salicylic acid and 75% as salicyluric acid, as the phenolic and acyl glucuronides, in urine. Specific Populations Geriatric Patients: Dipyridamole: In ESPS2 [see Clinical Studies ( 14 )] , plasma concentrations (determined as AUC) of dipyridamole in healthy elderly subjects (>65 years) were about 40% higher than in subjects younger than 55 years receiving treatment with aspirin and extended-release dipyridamole. Hepatic Dysfunction: No study has been conducted with aspirin and extended-release dipyridamole in patients with hepatic dysfunction. Dipyridamole: In a study conducted with an intravenous formulation of dipyridamole, patients with mild to severe hepatic insufficiency showed no change in plasma concentrations of dipyridamole but showed an increase in the pharmacologically inactive monoglucuronide metabolite. Dipyridamole can be dosed without restriction as long as there is no evidence of hepatic failure. Aspirin: Avoid aspirin in patients with severe hepatic insufficiency. Renal Dysfunction: Dipyridamole: In ESPS2 patients [see Clinical Studies ( 14 )] , with creatinine clearances ranging from about 15 mL/min to >100 mL/min, no changes were observed in the pharmacokinetics of dipyridamole or its glucuronide metabolite if data were corrected for differences in age. Aspirin: Avoid aspirin in patients with severe renal failure (glomerular filtration rate <10 mL/min). Drug Interaction Studies A dedicated drug interaction study was conducted in 60 healthy volunteers to evaluate the effects of omeprazole 80 mg administered once daily on the pharmacokinetics (PK) of dipyridamole and the pharmacodynamics (PD) of acetylsalicylic acid when co-administered with aspirin and extended-release dipyridamole twice daily. Dipyridamole exposure (C max and AUC) at steady-state were similar with or without omeprazole co-administration. The pharmacokinetics of acetylsalicylic acid was not characterized. However, the antiplatelet activity as measured by arachidonic acid induced platelet aggregation was similar between the treatment arms at steady-state.