Gtn

# Gtn ## Overview - **Classification**: Organic nitrate, vasodilator. - **Mechanism**: Converted to nitric oxide (NO) in smooth muscle, increasing cGMP. This leads to vascular smooth muscle relaxation, primarily venodilation, reducing preload. ## Primary Indications 1. **Angina Pectoris (Acute/Chronic)**: Symptomatic relief and prophylaxis. 2. **Hypertensive Emergency**: Rapid blood pressure reduction. 3. **Acute Decompensated Heart Failure**: Especially with pulmonary edema. ## Adult Dosing ### Standard Dosing **Acute Angina Pectoris / Prophylaxis** - **Dose**: **0.3 mg** to **0.6 mg** (Sublingual tablet/spray). - **Frequency**: Repeat every **5 minutes** for up to **3 doses** in 15 minutes. - **Route**: Sublingual or buccal. - **Special Considerations**: If no relief, seek immediate medical attention. **Chronic Angina Prophylaxis** - **Dose**: **0.2 mg/hr** to **0.8 mg/hr** (Transdermal patch). - **Frequency**: Once daily, remove for **10-12 hours** to prevent tolerance. - **Route**: Transdermal. **Hypertensive Emergency / Acute Heart Failure** - **Dose**: Initial **5 mcg/min**. - **Frequency**: Titrate by **5 mcg/min** every **3-5 minutes** as needed. - **Route**: Intravenous infusion. - **Maximum Dose**: Typically **200 mcg/min**, but usually **20-100 mcg/min**. - **Special Considerations**: Requires continuous BP and HR monitoring. ### Dose Adjustments - **Renal Impairment**: No specific adjustments for short-term use. - **Hepatic Impairment**: No specific adjustments. - **Elderly Patients**: Start with lower doses due to increased sensitivity to hypotensive effects. ## Pediatric Dosing *Limited data available. Use with extreme caution and under specialist supervision for critical conditions only.* ### Neonates (0-28 days) - **Special Notes**: Not routinely used. Limited case reports for severe conditions like pulmonary hypertension; not standardized. ### Infants (1-12 months) - **Special Notes**: Not routinely used. Limited data for critical conditions. Risk of profound hypotension. ### Children (1-12 years) - **Primary Indication**: Primarily for **hypertensive crisis** or **severe acute heart failure** (IV infusion). - **Dose**: Initial **0.25 mcg/kg/min**. - **Frequency**: Titrate by **0.25-0.5 mcg/kg/min** every **15-20 minutes**. - **Maximum**: Up to **5 mcg/kg/min** (rarely 10 mcg/kg/min). - **Special Notes**: Requires continuous hemodynamic monitoring in an ICU setting. ### Adolescents (13-18 years) - **Dose**: Approach adult dosing, start at the lower end and titrate carefully. - **Maximum**: Adult maximum dose. ## Safety Information ### Contraindications - **Absolute**: Concomitant use of **PDE5 inhibitors** (e.g., sildenafil, tadalafil) due to severe hypotension. - **Absolute**: Severe anemia. - **Absolute**: Increased intracranial pressure (e.g., head trauma, cerebral hemorrhage). - **Absolute**: Hypersensitivity to nitrates. - **Relative**: Circulatory failure (shock, severe hypotension), constrictive pericarditis. ### Common Adverse Effects - **Very Common (>10%)**: Headache ("nitrate headache"), Dizziness, Flushing. - **Common (1-10%)**: Hypotension, Reflex tachycardia, Nausea, Vomiting. - **Serious but Rare**: Syncope, Methemoglobinemia (rare at typical doses), Paradoxical bradycardia. ### Key Drug Interactions - **PDE5 Inhibitors (e.g., Sildenafil)**: Life-threatening **profound hypotension**. **ABSOLUTELY CONTRAINDICATED**. - **Riociguat**: Significant hypotension. **Contraindicated**. - **Antihypertensives/Alcohol**: Enhanced hypotensive effects. Monitor blood pressure closely. - **Ergot Alkaloids (e.g., Ergotamine)**: Increased risk of ergotism. Avoid concomitant use. ## Monitoring & Follow-up - **Before Treatment**: Baseline blood pressure and heart rate. Assess for contraindications. - **During Treatment**: - **IV infusion**: Continuous BP and HR monitoring. ECG monitoring. - **Sublingual/Transdermal**: Monitor BP and HR regularly, assess symptom relief. - **Clinical Signs**: Watch for headache, dizziness, lightheadedness, syncope (signs of hypotension). ## Clinical Pearls - 💡 **Acute Angina**: Advise patients to sit or lie down before taking sublingual NTG to prevent falls from orthostatic hypotension. - 💡 **Tolerance**: For chronic use, a daily **nitrate-free interval** of 10-12 hours (e.g., removing patch overnight) is crucial to prevent tolerance. - 💡 **Storage**: Sublingual tablets are light/moisture sensitive. Keep in original glass bottle, tightly capped. Replace every 6 months after opening. - 💡 **Emergency**: If chest pain persists after 3 doses of sublingual NTG (taken 5 mins apart), patient should call emergency services immediately. > **⚠️ Important**: This information is for educational purposes only. Always consult current prescribing information, local guidelines, and clinical judgment before prescribing.