"What are calcium channel blockers (CCBs) and how do they work?
Calcium channel blockers are drugs that block the entry of calcium into the muscle cells of the heart and arteries.
- The entry of calcium is critical for"...
Because DynaCirc® (isradipine) decreases peripheral resistance, like other calcium blockers DynaCirc® (isradipine) may occasionally produce symptomatic hypotension. However, symptoms like syncope and severe dizziness have rarely been reported in hypertensive patients administered DynaCirc® (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 DynaCirc® (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.
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 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 DynaCirc® (isradipine) during pregnancy should only be considered if the potential benefit outweighs potential risks.
It is not known whether DynaCirc® (isradipine) is excreted in human milk. Because many drugs are excreted in human milk, and because of the potential for adverse effects of DynaCirc® (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.
Last reviewed on RxList: 4/22/2009
This monograph has been modified to include the generic and brand name in many instances.
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