Nifedipine

Nifedipine is indicated in the management of all types of essential & renal hypertension. Also indicated in the management of hypertension during pregnancy & during coronary by pass surgery.

Nifedipine is also used for prophylaxis and the treatment of unstable & variant angina, myocardial infarction, and silent myocardial ischaemia. Moreover Nifedipine is also used in Raynaud's phenomenon & heart failure.

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.

• ACE inhibitors: Enhanced hypotensive effect.
• Anti-arrythmics: Plasma concentration of quinidine is reduced.
• Anti-bacterials: Rifampicin possibly increases metabolism of Nifedipine.
• Anti-epileptics: Plasma concentration of phenytoin increases.
• Antipsychotics: Enhanced hypotensive effect.
• β-blockers: Occasionally severe hypotension and heart failure may occur.
• Cyclosporin: Plasma concentration of Nifedipine possibly increases.
• Muscle relaxants: Effect of muscle relaxants e.g. tubocurarine increases.
• Ulcer healing drugs: Metabolism of Nifedipine increases.

Cardiogenic shock, advanced aortic stenosis, nursing mothers, GI obstruction, inflammatory bowel disease, hypotension.

Headache, flushing, lethargy, gravitational oedema rash, nausea, increased frequency of micturation, eye pain, gum hyperplasia, depression, tremor, photosensitivity and few cases of jaundice have been reported. These reactions may regress on discontinuation of therapy. Its introduction may induce attacks of ischaemic pain in some patients with angina pectoris.

There are no adequate and well controlled studies in pregnant women. It should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

Tablets should be swallowed whole and should not be bitten, chewed or broken up. It should be used with caution in patient whose cardiac reserve is poor. Should be withdrawn if ischaemic pain occurs or existing pain worsens shortly after initiating treatment. Use in diabetic patients requires adjustment of their control. Since the absorption of the drug could be modified by renal disease, caution should be exercised in treating such patients.

Calcium-channel blockers

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