Nifedipine is an inhibitor of Calcium Channel Blocker that blocks the transmembrane influx of Calcium ions into muscle cells. Nifedipine has selective effects as a dilator of arterial vessels. Nifedipine dilates main coronary and systemic arteries. As a result blood pressure falls and this elicits a sympathetic reflex response causing tachycardia and an increased cardiac output. Pulmonary arterial pressure also falls. Nifedipine has direct negative inotropic effects on cardiac muscles and these effects are seen at higher doses than dose which causes arterial vasodilatation.
Nifedipine 10 mg-
Angina: Initially 10 mg 3 times daily with food increased to 20 mg 3 times daily if necessary, in elderly patients, initially 5 mg 3 times daily.
Raynaud’s Phenomenon: 10 mg 3 times daily; maximum 60 mg daily. In urgent cases, the tablet should be dissolved under the tongue like a sublingual tablet. The effect occurs within some minutes.
Nifedipine 20 mg: The starting dose for patients, not previously prescribed Nifedipine products is one tablet once daily. The recommended dose in hypertension and angina prophylaxis is 20 mg twice daily during or after food. Dosage may be adjusted within the range 10 mg twice daily to 40 mg twice daily.
Patients with liver dysfunction should commence therapy with 10 mg twice daily with careful monitoring.
Patients with renal impairment do not require adjustment of dosage.