Nifedipine

# Nifedipine ## Overview - **Classification**: Dihydropyridine Calcium Channel Blocker (CCB). - **Mechanism**: Inhibits calcium ion influx into vascular smooth muscle and myocardial cells, leading to peripheral vasodilation and decreased systemic vascular resistance. ## Primary Indications 1. **Hypertension**: Management of essential hypertension. 2. **Vasospastic Angina**: Treatment of Prinzmetal's or variant angina. 3. **Chronic Stable Angina**: Management of chronic stable angina pectoris. ## Adult Dosing ### Standard Dosing **Hypertension / Chronic Stable Angina / Vasospastic Angina (Extended-Release)** - **Dose**: Start with **30 mg** or **60 mg**. - **Frequency**: Once daily. - **Route**: Oral. - **Maximum Dose**: **90 mg** to **120 mg** once daily (depending on patient response and formulation). ### Dose Adjustments - **Renal Impairment**: No specific dose adjustment generally needed. Use with caution. - **Hepatic Impairment**: Start with a lower dose (e.g., **30 mg** ER once daily). Monitor closely for adverse effects. - **Elderly Patients**: Start with lower doses (e.g., **30 mg** ER once daily) due to increased sensitivity and risk of adverse effects. ## Pediatric Dosing *(Nifedipine use in pediatrics is limited and often off-label, primarily for acute severe hypertension)* ### Neonates (0-28 days) - **Dose**: Generally **avoided** due to limited safety and efficacy data. - **Special Notes**: Consult a specialist for specific conditions like PPHN where its use might be considered cautiously. ### Infants (1-12 months) - **Indication**: Acute severe hypertension (immediate-release formulation). - **Dose**: **0.1 - 0.25 mg/kg/dose**. - **Frequency**: Every 4-6 hours as needed. - **Maximum**: **0.5 mg/kg/dose** or **10 mg/dose** (single dose). - **Special Notes**: Not recommended for chronic use. Risk of precipitous hypotension. ### Children (1-12 years) - **Indication**: Acute severe hypertension (immediate-release formulation). - **Dose**: **0.25 - 0.5 mg/kg/dose**. - **Frequency**: Every 4-6 hours as needed. - **Maximum**: **0.5 mg/kg/dose** or **10 mg/dose** (single dose). Total daily maximum **1-2 mg/kg/day**. - **Special Notes**: Sublingual administration is **not recommended** due to unpredictable absorption and rapid, uncontrolled BP drops. ### Adolescents (13-18 years) - **Dose**: Approach adult dosing, starting with the lower end of the extended-release range (e.g., **30 mg** ER). - **Maximum**: Adult maximum dose **90-120 mg** ER once daily. - **Special Notes**: Closely monitor blood pressure and heart rate. ## Safety Information ### Contraindications - **Absolute**: Hypersensitivity to nifedipine or other dihydropyridines. - **Absolute**: Cardiogenic shock, acute myocardial infarction (within 2-4 weeks), unstable angina. - **Absolute**: Concurrent use with strong CYP3A4 inducers (e.g., rifampin). - **Relative**: Severe aortic stenosis. ### Common Adverse Effects - **Very Common (>10%)**: Peripheral edema, headache, flushing. - **Common (1-10%)**: Dizziness, palpitations, nausea, fatigue, constipation. - **Serious but Rare**: Hypotension, myocardial infarction, Stevens-Johnson Syndrome, angioedema. ### Key Drug Interactions - **Strong CYP3A4 Inhibitors (e.g., ketoconazole, clarithromycin, grapefruit juice)**: Significantly increases nifedipine levels. Monitor for toxicity (hypotension, flushing). Avoid grapefruit juice. - **CYP3A4 Inducers (e.g., rifampin, phenytoin)**: Decreases nifedipine levels. Concurrent use with rifampin is contraindicated. - **Beta-Blockers**: Increased risk of profound hypotension, bradycardia, or heart failure. Monitor blood pressure and heart rate closely. - **Digoxin**: May increase digoxin levels. Monitor digoxin levels if co-administered. ## Monitoring & Follow-up - **Before Treatment**: Obtain baseline blood pressure (BP) and heart rate (HR). - **During Treatment**: Monitor BP regularly, especially during initiation and dose titration. Assess for peripheral edema. - **Clinical Signs**: Watch for signs of excessive hypotension (dizziness, syncope), worsening angina, or severe peripheral edema. ## Clinical Pearls - 💡 **Tip 1**: Nifedipine extended-release (ER) tablets should be swallowed whole; **do not chew, crush, or divide**. - 💡 **Tip 2**: A "ghost tablet" or tablet shell may appear in the stool with ER formulations; this is normal and means the medication was absorbed. - 💡 **Tip 3**: Avoid grapefruit juice entirely while on nifedipine, as it can dangerously increase drug levels. - 💡 **Tip 4**: Immediate-release (IR) nifedipine is generally **not recommended** for chronic hypertension due to rapid onset, unpredictable BP drops, and reflex tachycardia. > **⚠️ Important**: This information is for educational purposes only. Always consult current prescribing information, local guidelines, and clinical judgment before prescribing.