CILOSTAZOL

Cilostazol, USP is a quinolinone derivative that inhibits cellular phosphodiesterase (more specific for phosphodiesterase III). Cilostazol, USP is 6-[4-(1-cyclohexyl-1H-tetrazol-5-yl)butoxy]-3,4-dihydro-2(1H)-quinolinone, CAS-73963-72-1. The structural formula is: [Chemical Structure for Cilostazol] C20H27N5O2 M.W. 369.46 Cilostazol, USP occurs as white to off-white crystals or as a crystalline powder that is slightly soluble in methanol and ethanol, and is practically insoluble in water, 0.1 N HCl, and 0.1 N NaOH. Cilostazol tablets USP for oral administration are available in 50 mg pillow-shaped and 100 mg round, white to off-white debossed tablets. Each tablet, in addition to the active ingredient, contains the following inactive ingredients: colloidal silicon dioxide, corn starch, crospovidone, magnesium stearate, microcrystalline cellulose, and povidone. Meets USP Dissolution Test 3.

Cilostazol tablets are indicated for the reduction of symptoms of intermittent claudication, as demonstrated by an increased walking distance.

1 Recommended Dosage The recommended dosage of cilostazol tablets is 100 mg twice daily taken at least half an hour before or two hours after breakfast and dinner. Patients may respond as early as 2 to 4 weeks after the initiation of therapy, but treatment for up to 12 weeks may be needed before a beneficial effect is experienced. If symptoms are unimproved after 3 months, discontinue cilostazol tablets. 2.2 Dose Reduction With CYP3A4 and CYP2C19 Inhibitors Reduce dose to 50 mg twice daily when coadministered with strong or moderate inhibitors of CYP3A4 (e.g., ketoconazole, itraconazole, erythromycin, and diltiazem) or inhibitors of CYP2C19 (e.g., ticlopidine, fluconazole, and omeprazole) [see Drug Interactions (7.1)].

Cilostazol tablets are contraindicated in patients with: Heart failure of any severity: Cilostazol and several of its metabolites are inhibitors of phosphodiesterase III. Several drugs with this pharmacologic effect have caused decreased survival compared to placebo in patients with class III-IV heart failure. Hypersensitivity to cilostazol or any components of cilostazol tablets (e.g., anaphylaxis, angioedema)

The following adverse reactions are discussed in greater detail in other sections of the labeling: - Patients with Heart Failure [see BOXED WARNING] - Tachycardia [see Warnings and Precautions (5.1)] - Left Ventricular Outflow Tract Obstruction [see Warnings and Precautions (5.2)] - Hematologic Adverse Reactions [see Warnings and Precautions (5.3)] -Hemostatic Disorders or Active Pathologic Bleeding [see Warnings and Precautions (5.4)] 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. Adverse reactions were assessed in eight placebo-controlled clinical trials involving patients exposed to either 50 or 100 mg twice daily cilostazol (n = 1301) or placebo (n = 973), with a median treatment duration of 127 days for patients on cilostazol and 134 days for patients on placebo. The most frequent adverse reaction resulting in discontinuation of therapy in more than 3% of patients treated with cilostazol was headache [50 mg twice daily (1.3%), 100 mg twice daily (3.5%) and placebo (0.3%)]. Other frequent causes of discontinuation included palpitation and diarrhea, both 1.1% for cilostazol (all doses) versus 0.1% for placebo. The most common adverse reactions, occurring in at least 2% of patients treated with cilostazol 50 or 100 mg twice daily, are shown in Table 1. Table 1: Most Common Adverse Reactions in Patients on Cilostazol 50 or 100 mg Twice Daily (Incidence at least 2% and Occurring More Frequently (≥ 2%) in the 100 mg Twice Daily Group than on Placebo) Adverse Reactions Placebo (N = 973) Cilostazol 50 mg twice daily (N = 303) Cilostazol 100 mg twice daily (N = 998) Headache 14% 27% 34% Diarrhea 7% 12% 19% Abnormal stools 4% 12% 15% Palpitation 1% 5% 10% Dizziness 6% 9% 10% Pharyngitis 7% 7% 10% Infection 8% 14% 10% Peripheral edema 4% 9% 7% Rhinitis 5% 12% 7% Dyspepsia 4% 6% 6% Abdominal pain 3% 4% 5% Tachycardia 1% 4% 4% Less frequent clinical significant adverse reactions (less than 2%) that were experienced by patients treated with cilostazol 50 mg twice daily or 100 mg twice daily in the eight controlled clinical trials and that occurred at a frequency in the 100 mg twice daily group greater than in the placebo group are listed below. Body as a whole: fever, generalized edema, malaise Cardiovascular: atrial fibrillation, heart failure, myocardial infarction, nodal arrhythmia, supraventricular tachycardia, ventricular extrasystoles, ventricular tachycardia Digestive: anorexia, melena Hematologic and Lymphatic: anemia Metabolic and Nutritional: increased creatinine, hyperuricemia Nervous: insomnia Respiratory: epistaxis Skin and Appendages: urticaria Special Senses: conjunctivitis, retinal hemorrhage, tinnitus Urogenital: urinary frequency 6.2 Postmarketing Experience The following adverse reactions have been identified during post-approval use of cilostazol. Because these reactions are reported voluntarily from a population of an unknown size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure. Blood and lymphatic system disorders: Aplastic anemia, granulocytopenia, pancytopenia, bleeding tendency Cardiac disorders: Torsade de pointes and QTc prolongation in patients with cardiac disorders (e.g., complete atrioventricular block, heart failure; and bradyarrythmia), angina pectoris. Gastrointestinal disorders: Gastrointestinal hemorrhage, vomiting, flatulence, nausea General disorders and administration site conditions: Pain, chest pain, hot flushes Hepatobiliary disorders: Hepatic dysfunction/abnormal liver function tests, jaundice Immune system disorders: Anaphylaxis, angioedema, and hypersensitivity Investigations: Blood glucose increased, blood uric acid increased, increase in BUN (blood urea increased), blood pressure increase Nervous system disorders: Intracranial hemorrhage, cerebral hemorrhage, cerebrovascular accident, extradural hematoma and subdural hematoma Renal and urinary disorders: Hematuria Respiratory, thoracic and mediastinal disorders: Pulmonary hemorrhage, interstitial pneumonia Skin and subcutaneous tissue disorders: Hemorrhage subcutaneous, pruritus, skin eruptions including Stevens-Johnson syndrome, skin drug eruption (dermatitis medicamentosa), rash Vascular disorders: Subacute stent thrombosis, hypertension.

1 Inhibitors of CYP3A4 or CYP2C19 Inhibitors of CYP3A4 Coadministration of strong (e.g., ketoconazole) and moderate (e.g., erythromycin, diltiazem and grapefruit juice) CYP3A4 inhibitors can increase exposure to cilostazol. Reduce cilostazol dose to 50 mg twice daily when coadministered with strong or moderate inhibitors of CYP3A4 [see Dosage and Administration (2.2) and Clinical Pharmacology (12.3)]. Inhibitors of CYP2C19 Coadministration with CYP2C19 inhibitors (e.g., omeprazole) increases systemic exposure of cilostazol active metabolites. Reduce cilostazol dose to 50 mg twice daily when coadministered with strong or moderate inhibitors of CYP2C19 [see Dosage and Administration (2.2) and Clinical Pharmacology (12.3)].