Nidipine SR

• Hypertension:
  Treatment of mild to moderate high blood pressure to reduce the risk of cardiovascular events such as stroke and myocardial infarction.
• Angina pectoris:
  Prevention and management of chronic stable angina and vasospastic (Prinzmetal’s) angina to relieve chest pain by improving coronary blood flow.
• Raynaud’s phenomenon:
  Off-label use to reduce vasospasm and improve blood flow in peripheral arteries.
• Hypertensive emergencies and acute coronary syndrome:
  Extended-release forms are sometimes used in controlled settings; immediate-release forms should be used cautiously.

• Route: Oral (immediate-release and extended-release tablets/capsules).
• Adults:
• Immediate-release: Initial dose 10 mg three times daily; may be increased up to 20 mg three times daily as tolerated.
• Extended-release: Start with 30–60 mg once daily; maximum dose up to 90–120 mg once daily depending on response.
• Pediatrics: Limited data; use only under specialist guidance with weight-based dosing.
• Elderly: Start with lower doses due to increased sensitivity; monitor closely.
• Renal impairment: No dosage adjustment typically required but monitor response.
• Hepatic impairment: Use with caution; dose adjustments may be necessary due to altered metabolism.
• Administration advice:
  Take extended-release formulations whole with water; do not crush or chew. Immediate-release tablets may be taken with or without food.

Nifedipine is a dihydropyridine calcium channel blocker that selectively inhibits the influx of extracellular calcium ions through L-type calcium channels in vascular smooth muscle and cardiac muscle. This inhibition leads to relaxation of arterial smooth muscle, resulting in vasodilation, decreased peripheral vascular resistance, and reduced myocardial oxygen demand. The net effect is lowered blood pressure and relief of angina by improving coronary blood flow.

• Absorption: Well absorbed orally; immediate-release forms peak plasma levels within 30–60 minutes; extended-release formulations provide sustained plasma levels.
• Bioavailability: Approximately 45–56% due to first-pass metabolism.
• Distribution: Widely distributed with high plasma protein binding (~92–98%).
• Metabolism: Extensive hepatic metabolism primarily by CYP3A4 enzyme to inactive metabolites.
• Elimination: Excreted mainly as metabolites via urine; negligible unchanged drug in urine.
• Half-life: Immediate-release 2–5 hours; extended-release 8–12 hours.

• Pregnancy: FDA Category C. Use only if clearly needed after risk-benefit assessment. Animal studies show some risk; human data limited.
• Lactation: Excreted in breast milk in small amounts; caution advised during breastfeeding.

• Calcium channel blocker
• Dihydropyridine subclass

• Known hypersensitivity to nifedipine or other dihydropyridines.
• Cardiogenic shock.
• Significant aortic stenosis.
• Unstable angina or myocardial infarction in acute phase (immediate-release).
• Severe hypotension (systolic BP <90 mmHg).

• Use cautiously in patients with heart failure or impaired left ventricular function.
• Monitor for excessive hypotension, especially in volume-depleted patients.
• May cause reflex tachycardia; use beta-blockers if necessary.
• Avoid abrupt withdrawal to prevent rebound hypertension or angina.
• Peripheral edema is common and should be monitored.
• Monitor liver function in patients with hepatic impairment.

• Common:
• Headache
• Flushing
• Dizziness
• Peripheral edema
• Palpitations or tachycardia
• Serious/Rare:
• Hypotension
• Gingival hyperplasia
• Hepatotoxicity
• Rarely, arrhythmias or angina worsening

• CYP3A4 inhibitors (e.g., ketoconazole, erythromycin): Increase nifedipine plasma levels; risk of toxicity.
• CYP3A4 inducers (e.g., rifampin, phenytoin): Decrease plasma levels; reduced efficacy.
• Beta-blockers: May reduce reflex tachycardia but increase risk of heart block.
• Grapefruit juice: Inhibits CYP3A4, increasing nifedipine levels and side effects.
• Other antihypertensives: Additive blood pressure lowering effects; monitor for hypotension.

• Recent hypertension guidelines recommend nifedipine as an effective calcium channel blocker option for hypertension and angina.
• Extended-release formulations preferred for hypertension to reduce side effects and improve compliance.
• New warnings emphasize caution with immediate-release nifedipine in acute coronary syndromes due to risk of increased mortality.

• Store at 20°C to 25°C (68°F to 77°F).
• Protect from moisture and light.
• Keep tablets/capsules in tightly closed containers.
• Keep out of reach of children.