| name | Verapamil |
| classification | Calcium Channel Blocker, Non-dihydropyridine |
| pharmacokinetics | | absorption | Well absorbed from the gastrointestinal tract; peak plasma levels occur 1-4 hours after oral administration. First-pass metabolism is significant. | | distribution | Distributes throughout the body, including the heart and vascular smooth muscle. | | metabolism | Metabolized extensively in the liver. The major metabolite is inactive and excreted in the urine. | | excretion | Excreted primarily in the urine, both as unchanged drug and metabolites. |
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| suggested dosage | | note | Dosage must be individualized based on patient's response and condition. Consult with a physician for appropriate dosage. | | oral | Initial dosage may range from 80 mg to 120 mg orally three times daily. Titrate upward slowly until target effect is achieved. Common maintenance doses range between 120-480 mg daily. |
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| indications | | 1 | Angina pectoris | | 2 | Hypertension | | 3 | Supraventricular tachyarrhythmias (e.g., atrial fibrillation, atrial flutter) | | 4 | Migraine prophylaxis (in some cases) | | 5 | Essential tremor |
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| safety in pregnancy | | category | C | | note | Verapamil may cross the placenta and cause potential harm to the fetus. Use during pregnancy only if the potential benefit outweighs the risk, and under careful consideration and close monitoring by an obstetrician. |
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| safety in breastfeeding | | note | Verapamil is excreted in breast milk. The potential risk to a nursing infant needs to be carefully evaluated and compared with the potential benefit to the mother. Close monitoring by a healthcare professional is essential. |
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| side effects | | 1 | Constipation | | 2 | Headache | | 3 | Dizziness | | 4 | Bradycardia | | 5 | Hypotension | | 6 | Peripheral edema (in some patients) | | 7 | Fatigue | | 8 | Heart block (severe cases) | | 9 | AV block (atrioventricular block) |
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| alternatives | |
| contraindications | | 1 | Severe hypotension | | 2 | Severe bradycardia | | 3 | Second- or third-degree heart block | | 4 | Sick sinus syndrome | | 5 | Hypersensitivity to verapamil |
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| interactions | | 1 | | drug | CYP3A4 inhibitors (e.g., ketoconazole, erythromycin) | | effect | Increase verapamil levels, potentially leading to increased side effects. |
| | 2 | | drug | CYP3A4 inducers (e.g., rifampin) | | effect | Decrease verapamil levels, potentially reducing effectiveness. |
| | 3 | | drug | Beta-blockers | | effect | Additive bradycardic and hypotensive effects. Careful monitoring and dose adjustment may be necessary. |
| | 4 | | drug | Digoxin | | effect | Increased digoxin levels, potentially leading to digoxin toxicity. |
| | 5 | | drug | Cimetidine | | effect | Increase verapamil concentrations. |
| | 6 | | drug | Grapefruit juice | | effect | Can increase verapamil concentrations. |
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| warnings and precautions | | 1 | Careful monitoring of blood pressure and heart rate is essential, especially during the initial dose titration period. | | 2 | Patients with pre-existing heart conditions should be monitored closely. | | 3 | Patients with liver or kidney dysfunction may require dosage adjustment. | | 4 | Avoid abrupt discontinuation of the drug, as it may worsen symptoms. | | 5 | Verapamil can potentiate the effects of other medications that decrease heart rate. |
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| additional information | Verapamil is a potent vasodilator and should be used with caution in patients with hypotension. Verapamil has been reported to cause gingival hyperplasia in some cases. Always consult with a qualified healthcare professional before starting or discontinuing verapamil. |
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