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Brian Pinto, Pharm.D.
10-26-2010
- Hypertension
- See attached table for calcium channel blocker - specific indications
- Though chemically dissimilar, all of the calcium channel blockers inhibit the influx of extracellular calcium across the myocardial and vascular smooth muscle cell membranes.
- Classes include dihydropyridine (amlodipine, felodopine, nifedipine) and non-dihydropyridine (verapamil, diltiazem)
- Amlodipine: initial dose 5 mg daily; maximum dose 10 mg daily
- Nifedipine (extended-release): initial 30 or 60 mg once daily; maximum: 90-120 mg/day
- Diltiazem extended-release (once daily): initial 180-240 mg once daily; dose adjustment may be made after 14 days; maximum: 480 mg/day
- Verapamil (immediate-release): 80-320 mg/day divided in two daily doses
- Verapamil (extended-release): 120-480 mg/day in 1-2 divided doses
- Verapamil clearance may be reduced in patients with advanced renal failure
- Diltiazem is not removed by dialysis; no supplemental dose needed
- Verapamil dosage should be decreased to 30% of the normal dose.
- Amlodipine should be initiated at 2.5 mg oral daily for hypertension.
- Nifedipine clearance is reduced in patients with cirrhosis which may result in increased drug exposure
- Diltiazem half-life is increased in patients with cirrhosis
- Amlodipine, nifedipine, felodipine, verapamil, and diltiazem are Class C.
- Diltiazem and nifedipine are known to be excreted in breastmilk.
- Edema (amlodipine, nifedipine, felodipine)
- Bradycardia (verapamil, diltiazem)
- Constipation (verapamil)
- Potent CYP3A4 inhibitors have the potential to significantly reduce the metabolism of dihydropyridine calcium channel blockers leading to increased or prolonged effects of these agents.
- Avoid combining nifedipine and grapefruit juice. Studies demonstrate significant increases in plasma concentrations.
- While dihydropyridine calcium-channel blockers (e.g., nifedipine and amlodipine) may worsen proteinuria, in contrast, nondihydropyridine calcium-channel blockers (e.g. diltiazem and verapamil) may reduce overt proteinuria in diabetic nephropathy (Bakris; Smith; Remuzzi).
- Non-dihydropyridine calcium channel blockers are considered second line therapy for diabetic nephropathy and may be best used in combination with ACE inhibitors (Ruggenenti).
- Immediate-release nifedipine and nisoldipine should not be used for acute blood pressure reduction due to increased risk of adverse events (e.g., death, stroke, acute myocardial infarction) (Estacio).
- Calcium channel blockers (verapamil, diltiazem) may be associated with hyperglycemia as an uncommon side effect, however, this does not usually preclude their use in diabetes given its benefit as a potent anti-hypertensive agent (Louters; Levine).
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