From Ask Dr Wiki
Mechanism of action
- While all calcium channel blockers bind to this receptor, they have different binding sites also
- Blocking the L-channels or receptors inhibits inward calcium currents into the cell -> reducing the concentration of calcium needed for muscle contraction, leading to
- Smooth muscle dilation
- Decreasing contractility of heart muscle
- Slowing of the sinoatrial node firing rate
- Increasing AV nodal conductance time
Therapeutic uses
Dose
- Initial dose: 2.5 mg PO two times daily for immediate release product
- Maximum dose: 10 mg PO two times daily
Contraindications
- Hypersensitivity to the medications
- Short acting agents should not be used for hypertensive urgencies
- Acute myocardial infarction
- Acute stroke
Side effects
- Headache
- Peripheral edema
- Flushing
- Reflex tachycardia (short acting agents have higher incidence)
- Rash
- Dizziness
- Hypotension
Drug interactions (not inclusive)
- Grapefruit juice with certain dihydropyridines
- All medications that can lower blood pressure
- Fentanyl has been reported to cause severe hypotension when given with certain calcium channel blockers
- This reaction may occur with all calcium channel blockers, but no data available
- H2-receptor antagonists may increase the bioavailability of many of the dihydropyridine calcium channel blockers
Pharmacokinetics
- Onset: 120 minutes
- Half-life: 8 hours
- Elimination: hepatic
