Cilostazol Tablets, USP 50 mg and 100 mg Rx only

The mechanism of the effects of Cilostazol Tablets, USP on the symptoms of intermittent claudication is not fully understood.  Cilostazol Tablets, USP and several of its metabolities are cyclic AMP (cAMP) phosphodiesterase III inhibitors (PDE III inhibitors), inhibiting phosphodiesterase activity and suppressing cAMP degration with a resultant increase in cAMP in platelets and blood vessels, leading to inhibition of platelet aggregation and vasodilation, respectively.

Cilostazol Tablets, USP inhibits platelet aggregation induced by a variety of stimuli, including thrombin, ADP, collagen, arachidonic acid, epinephrine, and shear stress.  Effects on circulating plasma lipids have been examined in patients taking Cilostazol Tablets, USP.  After 12 weeks, as compared to placebo, Cilostazol Tablets, USP 100 mg b.i.d. produced a reduction in triglycerides of 29.3 mg/dL (15%) and an increase in HDL-cholesterol of 4.0 mg/dL (≡ 10%).

Cilostazol affects both vascular beds and cardiovascular function.  It produces non-homogeneous dilation of vascular beds, with greater dilation in femoral beds than in vertebral, carotid or superior mesenteric arteries.  Renal arteries were not responsive to the effects of cilostazol.

In dogs or cynomolgous monkeys, cilostazol increased heart rate, myocardial contractile force, and coronary blood flow as well as ventricular automaticity, as would be expected for a PDE III inhibitor.  Left ventricular contractility was increased at doses required to inhibit platelet aggregation.  A-V conduction was accelerated.  In humans, heart rate increased in a dose-proportional manner by a mean of 5.1 and 7.4 beats per minute in patients treated with 50 and 100 mg b.i.d., respectively.  In 264 patients evaluated with Holter monitors, numerically more cilostazol-treated patients had increases in ventricular premature beats and non-sustained ventricular tachycardia events than did placebo-treated; the increases were not dose-related.

Cilostazol Tablets, USP is absorbed after oral administration. A high fat meal increases absorption, with an approximately 90% increase in C_max and a 25% increase in AUC. Absolute bioavailability is not known. Cilostazol is extensively metabolized by hepatic cytochrome
P-450 enzymes, mainly 3A4, and, to a lesser extent, 2C19, with metabolites largely excreted in urine. Two metabolites are active, with one metabolite appearing to account for at least 50% of the pharmacologic (PDE III inhibition) activity after administration of Cilostazol Tablets, USP.   Pharmacokinetics are approximately dose proportional. Cilostazol and its active metabolites have apparent elimination half-lives of about 11 to 13 hours. Cilostazol and its active metabolites accumulate about 2-fold with chronic administration and reach steady state blood levels within a few days. The pharmacokinetics of cilostazol and its two major active metabolites were similar in healthy normal subjects and patients with intermittent claudication due to peripheral arterial disease (PAD).

The mean ± SEM plasma concentration-time profile at steady state after multiple dosing of Cilostazol Tablets, USP 100 mg b.i.d. is shown below:

Plasma Protein and Erythrocyte Binding:
Cilostazol is 95 to 98% protein bound, predominantly to albumin.  The mean percent binding for 3,4-dehydro-cilostazol is 97.4% and for 4'-trans-hydroxy-cilostazol is 66%.  Mild hepatic impairment did not affect protein binding.  The free fraction of cilostazol was 27% higher in subjects with renal impairment than in normal volunteers.  The displacement of cilostazol from plasma proteins by erythromycin, quinidine, warfarin, and omeprazole was not clinically significant.

Cilostazol is elminated predominately by metabolism and subsequent urinary excretion of metabolites.  Based on in vitro studies, the primary isoenzymes involved in cilostazol's metabolism are CYP3A4 and, to a lesser extent, CYP2C19.  The enzyme responsible for metabolism of 3,4-dehydro-cilostazol, the most active of the metabolites,is unknown.

Following oral administration of 100 mg radiolabeled cilostazol, 56% of the total analytes in plasma was cilostazol, 15% was 3,4-dehydro-cilostazol (4 to 7 times as active as cilostazol), and 4% was 4'-trans-hydroxy-cilostazol (one fifth as active as cilostazol). The primary route of elimination was via the urine (74%), with the remainder excreted in feces (20%).  No measurable amount of unchanged cilostazol was excreted in the urine, and less than 2% of the dose was excreted as 3,4-dehydro-cilostazol. About 30% of the dose was excreted in urine as 4'trans-hydroxy-cilostazol.  The remainder was excreted asother metabolites, non of which exceeded 5%.  There was no evidence of induction of hepatic microenzymes.

The total and unbound oral clearances, adjusted for body weight, of cilostazol and its metabolites were not significantly different with respect to age and/or gender across a 50-to-80-year-old age range.

Population pharmacokinetic analysis suggests that smoking decreased cilostazol exposure by about 20%.

The pharmacokinetics of cilostazol and its metabolites were similar with mild hepatic disease as compared to healthy subjects.

Patients with moderate or severe hepatic impairment have not been studied.

The total pharmacologic activity of cilostazol and its metabolites was similar in subjects with mild to moderate renal impairment and in normal subjects.  Severe renal impairment increases metabolite levels and alters protein bindingof the parent and metabolites.  The expected pharmacologic activity, however, based on plasma concentrations and relative PDE III inhibiting potency of patent drug and metabolites, appeared little changed.  Patients on dialysis have not been studied, but, it is unlikely that cilostazol can be removed efficiently by dialysis because of its high protein binding (95 to 98%).

Pharmacokinetic and Pharmacodynamic Drug-Drug Interactions:
Cilostazol could have pharmacodynamic interactions with other inhibitors of platelet function and pharmacokinetic interactions because of effects of other drugs on its metabolism by CYP3A4 or CYP2C19.  A reduced dose of Cilostazol Tablets, USP should be considered when taken concomitantly with CYP3A4 or CYP2C19 inhibitors.  Cilostazol does not appear to inhibit CYP3A4 (see Pharmacokinetic and Pharmacodynamic Drug-Drug Interactions, Lovastatin ).

Short-term (≤4 days) coadministration of aspirin with Cilostazol Tablets, USP increased the inhibition of arachidonic acid-induced ex vivoplatelet aggregation by 20% compared to Cilostazol Tablets, USP alone and by 48% compared to aspirin alone.  However, short-term coadministration of aspirin with Cilostazol Tablets, USP had no clinically significant impact on PT, aPTT, or bleeding time compared to aspirin alone.  Effects of long-term coadministration in the general population are unknown.  In eight randomized, placebo-controlled, double-blind clinical trials, aspirin was coadministered with cilostazol to 201 patients.  The most frequent doses and mean durations of aspirin therapy wer 75 to 81 mg daily for 137 days (107 patients) and 325 mg daily for 54 days (85 patients).  There was no apparent increases in incidence of hemorrhagic adverse effects in patients taking cilostazol and aspirin compared to patients taking placebo and equivalent doses of aspirin.

The cytochrome P-450 isoenzymes involved in the metabolism of R-warfarin are CYP3A4, CYP1A2, and CYP2C19, and in the metabolism of S-warfarin, CYP2C9.  Cilostazol did not inhibit either the metabolism or the pharmacologic effects (PT, aPTT, bleeding time, or platelet aggregation) of R- and S-warfarin after a single 25-mg dose of warfarin.  The effecr of concomitant multiple dosing of warfarin and Cilostozol Tablets, USP on the pharmacokinetics and pharmacodynamics of both drugs is unknown.

Mulitiple doses of clopidogrel do not significantly increase steadystate plasma concentrations of cilostzol.

Strong Inhibitors of CYP3A4:
A priming dose of ketoconazole 400 mg (a strong inhibitor of CYP3A4), was given one day prior to coadminstration of single doses of ketoconazole 400 mg and cilostazol 100 mg.  This regimen increased cilostazol C_max by 94% and AUC by 117%.  Other strong inhibitors of CYP3A4, such as intraconazole, fluconazole, miconazole, fluvoxamine, fluoxetine, nefazodone, and sertraline, would be expected to have a similar effect (see DOSAGE AND ADMINISTRATION ).

Moderate Inhibitors of CYP3A4:
1.  Erythromycin and other macrolide antibiotics:  Erythromycin is a moderately strong inhibitor of CYP3A4.  Coadministration of erythromycin 500 mg q 8h with a single dose of cilostazol 100 mg increased cilostazol C_max by 47% and AUC by 73%.  Inhibition of cilostazol metabolism by erythromycin increased the AUC of 4'-trans-hydroxy-cilostazol by 141%.  Other macrolide antibiotics (e.g., clarithromycin), but not all (e.g. azithromycin), would be expected to have a similar efect (see DOSAGE AND ADMINISTRATION ).
2.  Diltiazem:  Diltiazem 180 mg decreased the clearance of cilostazol by ~30% and AUC increased ~40% (see DOSAGE AND ADMINITRATION ).
3.  Grapefruit Juice:  Grapefruit juice increased the C_max of cilostazol by ~50%, but had not effect on AUC.

Omeprazole:  Coadministration of omeprazole did not significantly affect the metabolism of cilostazol, but the systemic exposure to 3,4-dehydro-cilostazol was increased by 69%, probably the result of omeprazole's potent inhibition of CYP2C19 (see DOSAGE AND ADMINISTRATION). 

Concomitant administration of quinidine with a single dose of cilostazol 100 mg did not alter cilostazol pharmacokinetics.

The concomitant administration of lovastatin with cilostazol decreases cilostazol C_{ss, max} and AUC, by 15%.  There is also a decrease, although nonsignificant, in cilostazole metaboite concentrations.  Coadministration of cilostazole with lovastatin increased lovastatin and β-hydroxi lovastatin AUC approximately 70%.  This is most likely clinically insignificant.

Rare cases have been reported of thrombocytopenia or leucopenia progressing to agranulocytosis when cilostazol was not immediately discontinued. The agranulocytosis, however, was reversible on discontinuation of Cilostazol.

There is limited information with respect to the efficacy or safety of the concurrent use of cilostazol and clopidogrel, a platelet-aggregation inhibiting drug indicated for use in patients with peripheral arterial disease. Although it cannot be determined whether there was an additive effect on bleeding times during concomitant administration with cilostazol and clopidogrel, caution is advised for checking bleeding times during coadministration.

Please refer to the patient package insert.
Patients should be advised:

• to read the patient package insert for Cilostazol Tablets USPcarefully before starting therapy and to reread it each time therapy is renewed in case the information has changed.
• to take cilostazol at least one-half hour before or two hours after food.
• that the beneficial effects of cilostazol on the symptoms of intermittent claudication may not be immediate. Although the patient may experience benefit in 2 to 4 weeks after initiation of therapy, treatment for up to 12 weeks may be required before a beneficial effect is experienced.

Patients with moderate or severe hepatic impairment have not been studied in clinical trials.

Special caution is advised when Cilostazol Tablets, USP is used in such patients.

Patients on dialysis have not been studied, but, it is unlikely that cilostazol can be removed efficiently by dialysis because of its high protein binding (95 to 98%).

Special caution is advised when Cilostazol Tablets, USP is used in patients with severe renal impairment; estimated creatinine clearence, <25 ml/min.

Since Cilostazol Tablets, USP is extensively metabolized by cytochrome P-450 isoenzymes, caution should be exercised when Cilostazol Tablets, USP is coadministered with inhibitors of CYP3A4 such as ketoconazole and erythromycin or inhibitors of CYP2C19 such as omeprazole. Pharmacokinetic studies have demonstrated that omeprazole and erythromycin significantly increased the systemic exposure of cilostazol and/or its major metabolites. Population pharmacokinetic studies showed higher concentrations of cilostazol among patients concurrently treated with diltiazem, an inhibitor of CYP3A4 (see CLINICAL PHARMACOLOGY, Pharmacokinetic andPharmacodynamic Drug-Drug Interactions). Cilostazol Tablets, USP does not, however, appear to cause increased blood levels of drugs metabolized by CYP3A4, as it had no effect on lovastatin, a drug with metabolism very sensitive to CYP3A4 inhibition.

Cilostazol Tablets, USP inhibits platelet aggregation but in a reversible manner.  Cuation is advised in patients at risk of bleeding from surgery or pathologic processes.  Platelet aggregability returns to normal within 96 hours of stopping Cilostazole Tablets, USP.  Cuation is advised in patients receiving both Cilostazol Tablets, USP and any other antiplatelet agent, or in patients with thrombocytopenia.

Repeated oral administration of cilostazol to dogs (30 or more mg/kg/day for 52 weeks, 150 or more mg/kg/day for 13 weeks, and 450 mg/kg/day for 2 weeks), produced cardiovascular lesions that included endocardial haemorrhage, hemosiderin deposition and fibrosis inthe left ventricle, haemorrhage in the right atrial wall, haemorrhage and necrosis of the smooth muscle in the wall of the coronary artery, intimal thickening of the coronary artery, and coronary arteritis and periarteritis.  At the lowest dose associated with cardiovascular lesions in the 52-week study, systemic exposure (AUC) tounbound cilostazol was less than that seen in humans at the maximum recommended human dose (MRHD) of 100 mg b.i.d.  Similar lesions have been reported in dogs following the administration of other positive inotropic agents (including PDE III inhibitors) and/or vasodilating agents.  No cardiovascular lesions were seen in rats following 5 or 13 weeks of administration of cilostazol at doses up to 1500 mg/kg/day.  At this dose, systemic exposures (AUCs) to unbound cilostazol were only about 1.5 and 5 times (male and female rats, respectively) the exposure seen in humans at the MRHD.  Cardiovascular lesionswere also not seen in rats following 52 weeks of administration of cilostazol at doses up to 150 mg/kg/day.  At this dose, systemic exposure (AUCs) tounbound cilostazol were about 0.5 and 5 times (male and female rates, respectively) the exposure in humans at the MRHD.  In female rats, cilostazol AUCs were similar at 150 and 1500 mg/kg/day.  Cardiovascular lesions were also not observed in monkeys after oral administration of cilostazol for 13 weeks at doses up to 1800 mg/kg/day.  While this dose of cilostazol produced pharmacologic effects in monkeys, plasma cilostazol levels were less than those seen in humans given the MRHD, and those seen in dogs given doses associated with cardiovascular lesions.

Dietary administration of cilostazol to male and female rats and mice for up to 104 weeks, at doses up to 500 mg/kg/day in rats and 1000 mg/kg/day in mice, revealed no evidence of carcinogenic potential. The maximum doses administered in both rat and mouse studies were, on a systemic exposure basis, less than the human exposure at the MRHD of the drug. Cilostazol tested negative in bacterial gene mutation, bacterial DNA repair, mammalian cell gene mutation, and mouse in vivo bone marrow chromosomal aberration assays. It was, however, associated with a significant increase in chromosomal aberrations in the in vitro Chinese Hamster Ovary Cell assay.

Cilostazol did not affect fertility or mating performance of male and female rats at doses as high as 1000 mg/kg/day. At this dose, systemic exposures (AUCs) to unbound cilostazol were less than 1.5 times in males, and about 5 times in females, the exposure in humans at the MRHD.

Pregnancy Category C: In a rat developmental toxicity study, oral administration of 1000 mg cilostazol/kg/day was associated with decreased fetal weights, and increased incidences of cardiovascular, renal, and skeletal anomalies (ventricular septal, aortic arch, and subclavian artery abnormalities, renal pelvic dilation, 14^th rib, and retarded ossification). At this dose, systemic exposure to unbound cilostazol in nonpregnant rats was about 5 times the exposure in humans given the MRHD. Increased incidences of ventricular septal defect and retarded ossification were also noted at 150 mg/kg/day (5 times the MRHD on a systemic exposure basis). In a rabbit developmental toxicity study, an increased incidence of retardation of ossification of the sternum was seen at doses as low as 150 mg/kg/day. In nonpregnant rabbits given 150 mg/kg/day, exposure to unbound cilostazol was considerably lower than that seen in humans given the MRHD, and exposure to 3,4-dehydro-cilostazol was barely detectable.

When cilostazol was administered to rats during late pregnancy and lactation, an increased incidence of stillborn and decreased birth weights of offspring was seen at doses of 150 mg/kg/day (5 times the MRHD on a systemic exposure basis).

There are no adequate and well-controlled studies in pregnant women.

Transfer of cilostazol into milk has been reported in experimental animals (rats). Because of the potential risk to nursing infants, a decision should be made to discontinue nursing or to discontinue cilostazol

The safety and effectiveness of cilostazol in pediatric patients have not been established.

Of the total number of subjects (n = 2274) in clinical studies of cilostazol, 56 percent were 65-years-old and over, while 16 percent were 75-years-old and over. No overall differences in safety or effectiveness were observed between these subjects and younger subjects, and other reported clinical experience has not identified differences in responses between the elderly and younger patients, but greater sensitivity of some older individuals cannot be ruled out. Pharmacokinetic studies have not disclosed any age-related effects on the absorption, distribution, metabolism, and elimination of cilostazol and its metabolites.

The following adverse events have been reported spontaneously from worldwide post-marketing experience since launch of cilostazol in the US.

• Blood and lymphatic system disorders:
  • agranulocytosis, aplastic anemia, granulocytopenia, thrombocytopenia, leukopenia, bleeding tendency
• Cardiac disorders:
  • Torsades de pointes, QTc prolongation (Torsades de pointes and QTc prolongation occurred in patients with cardiac disorders, e.g. complete atrioventricular block, cardiac failure and bradyarrythmia, when treated with cilostazol. Cilostazol was used “off label” due to its positive chronotropic action.)
• Gastrointestinal disorders:
  • gastrointestinal hemorrhage
• General disorders and administration site conditions:
  • pain, chest pain, hot flushes
• Hepatobiliary disorders:
  • hepatic dysfunction/abnormal liver function tests, jaundice
• Injury, poisoning and procedural complications:
  • extradural hematoma and subdural hematoma
• Investigations :
  • blood glucose increased, blood uric acid increased, platelet count decreased, white blood cell count decreased, increase in BUN (blood urea increased), blood pressure increase
• Nervous system disorders:
  • intracranial hemorrhage, cerebral hemorrhage, cerebrovascular accident
• 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)
• Vascular disorders:
  • subacute thrombosis (These cases of subacute thrombosis occurred in patients treated with aspirin and “off label” use of cilostazol for prevention of thrombotic complication after coronary stenting.)

The available data suggest that the dosage of cilostazol can be reduced or discontinued without rebound (i.e., platelet hyperaggregability).

Store at 20 to 25°C (68 to 77°F) excursions permitted to 15 to 30°C (59 to 86°F) [see USP Controlled Room Temperature].

Dispense in a tight container as defined in the USP/NF.

Keep this and all drugs out of the reach of children.

Rev. October 2009
MF # 334-04

Manufactured and Distributed by:
Corepharma LLC
Middlesex, NJ 08846

Relabeling and Repackaging by:
Physicians Total Care, Inc.
Tulsa, OK       74146

Cilostazol may improve the symptoms of patients with a medical condition called intermittent claudication.

Intermittent claudication is pain in the legs that occurs with walking and disappears with rest. It occurs because narrowing or blockage of the arteries decreases blood flow to the legs. The decreased blood flow does not supply enough oxygen to the leg muscles during walking, resulting in these painful leg cramps.

The three main treatments available for intermittent claudication are:

• Exercise. Your doctor may advise an exercise program.
• Medication. Your doctor may prescribe a medication such as cilostazol. (See Who should not take cilostazol?)
• Surgery. Your doctor may recommend a surgical procedure to bypass the blocked segment of the artery. Another procedure is called a percutaneous transluminal angioplasty. In this procedure, a catheter (a flexible tube) is inserted into the artery to reduce the blockage and improve blood flow.

• The exact way that many drugs work is not well understood. Although how cilostazol works is not completely clear, its main effects are to dilate (widen) the arteries supplying blood to the legs and to decrease the ability of platelets in the blood to stick together. Platelets are particles that circulate in the blood and play a role in clotting
• Cilostazol may reduce the leg pain that patients with intermittent claudication experience, allowing them to walk farther before their leg pain occurs.
• Improvement in symptoms may occur as soon as 2 weeks, but could take up to 12 weeks. If you have not noticed any benefit from cilostazol after 12 weeks you and your doctor may wish to discuss other forms of treatment.
• Sometimes blood vessel disease of the legs causes pain at rest or breakdown of skin in the leg. Cilostazol has not been shown to work in patients with these problems.

• Patients who have congestive heart failure (CHF) must not take cilostazol.
  The most common symptoms of CHF are shortness of breath and swelling of the legs. However, other conditions may also cause these symptoms.
• Patients who have bleeding problems, such as a bleeding peptic ulcer, must not take cilostazol.
  Cilostazol decreases the ability of blood particles, called platelets, to stick together and this can increase the risk of bleeding.
       It is important that you discuss with your doctor whether you have CHF or bleeding problems.
• Over 1,300 patients took cilostazol in studies that lasted for 3 to 6 months. The mortality rate in these patients was similar to placebo (less than 1%). These studies were too small to be sure there is not some increased risk of dying with longer use or in patients sicker than those in the studies.

• Follow your doctor"s advice about how to take cilostazol.
• You should take cilostazol twice a day, at least one half-hour before or two hours after breakfast and dinner. Take cilostazol at about the same times each day.
• Do not share cilostazol with anyone else. It was prescribed only for you.
• Keep cilostazol and all drugs out of the reach of children.

Certain drugs and foods can increase the amount of cilostazol in the blood. Because of this, your doctor may adjust your dose of cilostazol or even stop it if you are taking or are going to take one of the following medications.

This list does not include every drug that may interact with cilostazol. Therefore, you should tell your doctor about all medications that you are taking, including vitamins, herbal supplements and over-the-counter drugs you can buy without a prescription. You should also check with your doctor before taking a new medication after you have begun cilostazol.

Cilostazol may cause side effects including headache, diarrhea, abnormal stools, increased heart rate, and palpitations.

You should discuss possible side effects with your doctor before taking cilostazol and any time you think you are having a side effect.

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

This provides only a summary of information about cilostazol. If you have any questions about cilostazol, talk to your doctor.

Rev. October, 2009
MF # 334-04

Manufactured and Distributed by:Logo
Corepharma LLC
Middlesex, NJ 08846