Isradipine

Hypertension Isradipine is indicated in the management of hypertension. It may be used alone or concurrently with thiazide-type diuretics.

Isradipine is contraindicated in individuals who have shown hypersensitivity to any of the ingredients in the formulation.

None

General Blood Pressure: Because isradipine decreases peripheral resistance, like other calcium blockers isradipine may occasionally produce symptomatic hypotension. However, symptoms like syncope and severe dizziness have rarely been reported in hypertensive patients administered isradipine, particularly at the initial recommended doses (see DOSAGE AND ADMINISTRATION ). Use in Patients with Congestive Heart Failure: Although acute hemodynamic studies in patients with congestive heart failure have shown that isradipine reduced afterload without impairing myocardial contractility, it has a negative inotropic effect at high doses in vitro, and possibly in some patients. Caution should be exercised when using the drug in congestive heart failure patients, particularly in combination with a beta-blocker. Drug Interactions Nitroglycerin: Isradipine has been safely coadministered with nitroglycerin. Hydrochlorothiazide: A study in normal healthy volunteers has shown that concomitant administration of isradipine and hydrochlorothiazide does not result in altered pharmacokinetics of either drug. In a study in hypertensive patients, addition of isradipine to existing hydrochlorothiazide therapy did not result in any unexpected adverse effects, and isradipine had an additional antihypertensive effect. Propranolol: In a single dose study in normal volunteers, coadministration of propranolol had a small effect on the rate but no effect on the extent of isradipine bioavailability. Significant increases in AUC (27%) and C max (58%) and decreases in t max (23%) of propranolol were noted in this study. However, concomitant administration of 5 mg b.i.d. isradipine and 40 mg b.i.d. propranolol to healthy volunteers under steady-state conditions had no relevant effect on either drug’s bioavailability. AUC and C max differences were <20% between isradipine given singly and in combination with propranolol, and between propranolol given singly and in combination with isradipine. Cimetidine: In a study in healthy volunteers, a one-week course of cimetidine at 400 mg b.i.d. with a single 5 mg dose of isradipine on the sixth day showed an increase in isradipine mean peak plasma concentrations (36%) and significant increase in area under the curve (50%). If isradipine therapy is initiated in a patient currently receiving cimetidine, careful monitoring for adverse reactions is advised and downward dose adjustment may be required. Rifampicin: In a study in healthy volunteers, a six-day course of rifampicin at 600 mg/day followed by a single 5 mg dose of isradipine resulted in a reduction in isradipine levels to below detectable limits. If rifampicin therapy is required, isradipine concentrations and therapeutic effects are likely to be markedly reduced or abolished as a consequence of increased metabolism and higher clearance of isradipine. Warfarin: In a study in healthy volunteers, no clinically relevant pharmacokinetic or pharmacodynamic interaction between isradipine and racemic warfarin was seen when two single oral doses of warfarin (0.7 mg/kg body weight) were administered during 11 days of multiple-dose treatment with 5 mg b.i.d. isradipine. Neither racemic warfarin nor isradipine binding to plasma proteins in vitro was altered by the addition of the other drug. Digoxin: The concomitant administration of isradipine and digoxin in a single-dose pharmacokinetic study did not affect renal, nonrenal and total body clearance of digoxin. Fentanyl Anesthesia: Severe hypotension has been reported during fentanyl anesthesia with concomitant use of a beta blocker and a calcium channel blocker. Even though such interactions have not been seen in clinical studies with isradipine, an increased volume of circulating fluids might be required if such an interaction were to occur. Carcinogenesis, Mutagenesis, Impairment of Fertility Treatment of male rats for 2 years with 2.5, 12.5, or 62.5 mg/kg/day isradipine admixed with the diet (approximately 6, 31, and 156 times the maximum recommended daily dose based on a 50 kg man) resulted in dose dependent increases in the incidence of benign Leydig cell tumors and testicular hyperplasia relative to untreated control animals. These findings, which were replicated in a subsequent experiment, may have been indirectly related to an effect of isradipine on circulating gonadotropin levels in the rats; a comparable endocrine effect was not evident in male patients receiving therapeutic doses of the drug on a chronic basis. Treatment of mice for two years with 2.5, 15, or 80 mg/kg/day isradipine in the diet (approximately 6, 38, and 200 times the maximum recommended daily dose based on a 50 kg man) showed no evidence of oncogenicity. There was no evidence of mutagenic potential based on the results of a battery of mutagenic tests. No effect on fertility was observed in male and female rats treated with up to 60 mg/kg/day isradipine. Pregnancy Pregnancy Category C: Isradipine was administered orally to rats and rabbits during organogenesis. Treatment of pregnant rats with doses of 6, 20, or 60 mg/kg/day produced a significant reduction in maternal weight gain during treatment with the highest dose (150 times the maximum recommended human daily dose) but with no lasting effects on the mother or the offspring. Treatment of pregnant rabbits with doses of 1, 3, or 10 mg/kg/day (2.5, 7.5, and 25 times the maximum recommended human daily dose) produced decrements in maternal body weight gain and increased fetal resorption at the two higher doses. There was no evidence of embryotoxicity at doses which were not maternotoxic and no evidence of teratogenicity at any dose tested. In a peri/postnatal administration study in rats, reduced maternal body weight gain during late pregnancy at oral doses of 20 and 60 mg/kg/day isradipine was associated with reduced birth weights and decreased peri and postnatal pup survival. There are no adequate and well controlled studies in pregnant women. The use of isradipine during pregnancy should only be considered if the potential benefit outweighs potential risks. Nursing Mothers It is not known whether isradipine is excreted in human milk. Because many drugs are excreted in human milk, and because of the potential for adverse effects of isradipine on nursing infants, a decision should be made as to whether to discontinue nursing or discontinue the drug, taking into account the importance of the drug to the mother. Pediatric Use Safety and effectiveness in pediatric patients have not been established.

In multiple dose U.S. studies in hypertension, 1228 patients received isradipine alone or in combination with other agents, principally a thiazide diuretic, 934 of them in controlled comparisons with placebo or active agents. An additional 652 patients (which includes 374 normal volunteers) received isradipine in U.S. studies of conditions other than hypertension, and 1321 patients received isradipine in non-U.S. studies. About 500 patients received isradipine in long-term hypertension studies, 410 of them for at least 6 months. The adverse reaction rates given below are principally based on controlled hypertension studies, but rarer serious events are derived from all exposures to isradipine, including foreign marketing experience. Most adverse reactions were mild and related to the vasodilatory effects of isradipine (dizziness, edema, palpitations, flushing, tachycardia), and many were transient. About 5% of isradipine patients left studies prematurely because of adverse reactions (vs. 3% of placebo patients and 6% of active control patients), principally due to headache, edema, dizziness, palpitations, and gastrointestinal disturbances. The following table shows the most common adverse reactions, volunteered or elicited, considered by the investigator to be at least possibly drug related. The results for the isradipine treated patients are presented for all doses pooled together (reported by 1% or greater of patients receiving any dose of isradipine), and also for the two treatment regimens most applicable to the treatment of hypertension with isradipine: (1) initial and maintenance dose of 2.5 mg b.i.d., and (2) initial dose of 2.5 mg b.i.d. followed by maintenance dose of 5 mg b.i.d. Isradipine Adverse Experience All Doses N=934 % 2.5 mg b.i.d. 199 % 5 mg b.i.d.† 150 % 10 mg b.i.d.†† 59 % Placebo % Active Controls* 414 % Headache Dizziness Edema Palpitations 13.7 7.3 7.2 4.0 12.6 8.0 3.5 1.0 10.7 5.3 8.7 4.7 22.0 3.4 8.5 5.1 14.1 4.4 3.0 1.4 9.4 8.2 2.9

1.5 Fatigue Flushing Chest Pain Nausea 3.9 2.6 2.4 1.8 2.5 3.0 2.5 1.0 2.0 2.0 2.7 2.7 8.5 5.1 1.7 5.1 0.3 0.0 2.4 1.7 6.3 1.2 2.9

3.1 Dyspnea Abdominal Discomfort Tachycardia Rash 1.8 1.7 1.5 1.5 0.5 0.0 1.0 1.5 2.7 3.3 1.3 2.0 3.4 1.7 3.4 1.7 1.0 1.7 0.3 0.3 2.2 3.9 0.5

0.7 Pollakiuria Weakness Vomiting Diarrhea 1.5 1.2 1.1 1.1 2.0 0.0 1.0 0.0 1.3 0.7 1.3 2.7 3.4 0.0 0.0 3.4 0.0 0.0 0.3 2.0 <1.0 1.2 0.2 1.9 †Initial dose of 2.5 mg b.i.d. followed by maintenance dose of 5 mg b.i.d. †† Initial dose of 2.5 mg b.i.d. followed by sequential titration to 5 mg b.i.d., 7.5 mg b.i.d., and maintenance dose of 10 mg b.i.d. *Propranolol, prazosin, hydrochlorothiazide, enalapril, captopril. Except for headache, which is not clearly drug-related (see previous table), the more frequent adverse reactions listed show little change, or increase slightly, in frequency over time, as shown in the following table: Incidence Rates for Isradipine (All Doses) by Week (%) Week N 1 694 2 906 3 649 4 847 5 432 6 494 Adverse Reaction Headache Dizziness Edema Palpitations Fatigue Flushing 6.5 1.6 1.2 1.2 0.4 1.2 6.1 1.9 2.5 1.3 1.0 1.3 5.2 1.7 3.2 1.4 1.4 2.0 5.2 2.2 3.2 1.9 1.2 1.4 5.8 2.3 5.3 2.1 1.2 2.1 4.5 2.0 5.5 1.4 1.6

1.4 Week N 7 153 8 377 9 261 10 362 11 107 12 105 Adverse Reaction Headache Dizziness Edema Palpitations Fatigue Flushing 2.0 2.0 5.9 1.3 2.0 3.3 2.7 1.9 5.0 0.8 2.7 1.3 1.9 2.3 4.6 0.8 1.5 1.1 2.8 3.9 4.7 1.7 1.4 0.8 2.8 4.7 3.8 1.9 0.9 0.0 3.8 3.8 3.8 2.9 1.9

0.0 Edema, palpitations, fatigue, and flushing appear to be dose-related, especially at the higher doses of 15 to 20 mg/day. In open-label, long-term studies of up to two years in duration, the adverse events reported were generally the same as those reported in the short-term controlled trials. The overall frequencies of these adverse events were slightly higher in the long-term than in the controlled studies, but as in the controlled trials most adverse reactions were mild and transient. The following adverse experiences were reported in 0.5% to 1.0% of the isradipine-treated patients in hypertension studies, or are rare. More serious events from this and other data sources, including postmarketing exposure, are shown in italics. The relationship of these adverse events to isradipine administration is uncertain. Skin: pruritus, urticaria Musculoskeletal: cramps of legs/feet Respiratory: cough Cardiovascular: shortness of breath, hypotension, atrial fibrillation, ventricular fibrillation, myocardial infarction, heart failure Gastrointestinal: abdominal discomfort, constipation, diarrhea Urogenital: nocturia Nervous System: drowsiness, insomnia, lethargy, nervousness, impotence, decreased libido, depression, syncope , paresthesia (which includes numbness and tingling), transient ischemic attack, stroke Autonomic: hyperhidrosis, visual disturbance, dry mouth, numbness Miscellaneous: throat discomfort, leukopenia, elevated liver function tests To report SUSPECTED ADVERSE EVENTS, contact Teva at 1-888-838-2872 or FDA at 1-800-FDA-1088 or http://www.fda.gov/medwatch.

Nitroglycerin: Isradipine has been safely coadministered with nitroglycerin. Hydrochlorothiazide: A study in normal healthy volunteers has shown that concomitant administration of isradipine and hydrochlorothiazide does not result in altered pharmacokinetics of either drug. In a study in hypertensive patients, addition of isradipine to existing hydrochlorothiazide therapy did not result in any unexpected adverse effects, and isradipine had an additional antihypertensive effect. Propranolol: In a single dose study in normal volunteers, coadministration of propranolol had a small effect on the rate but no effect on the extent of isradipine bioavailability. Significant increases in AUC (27%) and C max (58%) and decreases in t max (23%) of propranolol were noted in this study. However, concomitant administration of 5 mg b.i.d. isradipine and 40 mg b.i.d. propranolol to healthy volunteers under steady-state conditions had no relevant effect on either drug’s bioavailability. AUC and C max differences were <20% between isradipine given singly and in combination with propranolol, and between propranolol given singly and in combination with isradipine. Cimetidine: In a study in healthy volunteers, a one-week course of cimetidine at 400 mg b.i.d. with a single 5 mg dose of isradipine on the sixth day showed an increase in isradipine mean peak plasma concentrations (36%) and significant increase in area under the curve (50%). If isradipine therapy is initiated in a patient currently receiving cimetidine, careful monitoring for adverse reactions is advised and downward dose adjustment may be required. Rifampicin: In a study in healthy volunteers, a six-day course of rifampicin at 600 mg/day followed by a single 5 mg dose of isradipine resulted in a reduction in isradipine levels to below detectable limits. If rifampicin therapy is required, isradipine concentrations and therapeutic effects are likely to be markedly reduced or abolished as a consequence of increased metabolism and higher clearance of isradipine. Warfarin: In a study in healthy volunteers, no clinically relevant pharmacokinetic or pharmacodynamic interaction between isradipine and racemic warfarin was seen when two single oral doses of warfarin (0.7 mg/kg body weight) were administered during 11 days of multiple-dose treatment with 5 mg b.i.d. isradipine. Neither racemic warfarin nor isradipine binding to plasma proteins in vitro was altered by the addition of the other drug. Digoxin: The concomitant administration of isradipine and digoxin in a single-dose pharmacokinetic study did not affect renal, nonrenal and total body clearance of digoxin. Fentanyl Anesthesia: Severe hypotension has been reported during fentanyl anesthesia with concomitant use of a beta blocker and a calcium channel blocker. Even though such interactions have not been seen in clinical studies with isradipine, an increased volume of circulating fluids might be required if such an interaction were to occur.

Pregnancy Category C: Isradipine was administered orally to rats and rabbits during organogenesis. Treatment of pregnant rats with doses of 6, 20, or 60 mg/kg/day produced a significant reduction in maternal weight gain during treatment with the highest dose (150 times the maximum recommended human daily dose) but with no lasting effects on the mother or the offspring. Treatment of pregnant rabbits with doses of 1, 3, or 10 mg/kg/day (2.5, 7.5, and 25 times the maximum recommended human daily dose) produced decrements in maternal body weight gain and increased fetal resorption at the two higher doses. There was no evidence of embryotoxicity at doses which were not maternotoxic and no evidence of teratogenicity at any dose tested. In a peri/postnatal administration study in rats, reduced maternal body weight gain during late pregnancy at oral doses of 20 and 60 mg/kg/day isradipine was associated with reduced birth weights and decreased peri and postnatal pup survival. There are no adequate and well controlled studies in pregnant women. The use of isradipine during pregnancy should only be considered if the potential benefit outweighs potential risks.

It is not known whether isradipine is excreted in human milk. Because many drugs are excreted in human milk, and because of the potential for adverse effects of isradipine on nursing infants, a decision should be made as to whether to discontinue nursing or discontinue the drug, taking into account the importance of the drug to the mother.

Safety and effectiveness in pediatric patients have not been established.

Isradipine is a dihydropyridine calcium channel blocker. It binds to calcium channels with high affinity and specificity and inhibits calcium flux into cardiac and smooth muscle. The effects observed in mechanistic experiments in vitro and studied in intact animals and man are compatible with this mechanism of action and are typical of the class. Except for diuretic activity, the mechanism of which is not clearly understood, the pharmacodynamic effects of isradipine observed in whole animals can also be explained by calcium channel blocking activity, especially dilating effects in arterioles which reduce systemic resistance and lower blood pressure, with a small increase in resting heart rate. Although like other dihydropyridine calcium channel blockers, isradipine has negative inotropic effects in vitro, studies conducted in intact anesthetized animals have shown that the vasodilating effect occurs at doses lower than those which affect contractility. In patients with normal ventricular function, isradipine’s afterload reducing properties lead to some increase in cardiac output. Effects in patients with impaired ventricular function have not been fully studied.