1. Clinical & Scientific Overview
Nitroglycerin (Glyceryl Trinitrate — GTN) (TIP-MED-000025, Reference Code [3.25]) is classified under
Cardiovascular & Antithrombotic Medicines (Ch 03) as a Organic Nitrate; Nitric Oxide (NO) Donor Venodilator & Coronary Vasodilator.
Within the Indian regulatory and compendial framework, it is governed under Schedule H Prescription Drug (To be sold by retail on the prescription of a Registered Medical Practitioner only — Drugs Rules 1945).
Warf (Cipla), Uniwarfin (Unichem)
Sublingual Tablets: 0.5 mg (500 mcg) GTN (or 5 mg Isosorbide Dinitrate SL); Sublingual Spray: 400 mcg/metered dose; Oral Controlled-Release (CR/TR) Tablets/Capsules: 2.6 mg, 6.4 mg
3. Mechanism of Action & Pharmacodynamics
Organic Nitrate; Nitric Oxide (NO) Donor Venodilator & Coronary Vasodilator acting on target receptor/enzyme pathways in Cardiovascular & Antithrombotic Medicines (Ch 03): clinical efficacy is mediated via Organic Nitrate; Nitric Oxide (NO) Donor Venodilator & Coronary Vasodilator for Sublingual Tablet/Spray: Acute relief and immediate pre-exertional prophylaxis of angina pectoris; Oral Controlled-Release (2.6 mg / 6.4 mg): Long-term prophylaxis of chronic stable angina pectoris..
4. Therapeutic Indications & Evidence-Supported Uses
- Sublingual Tablet/Spray: Acute relief and immediate pre-exertional prophylaxis of angina pectoris
- Oral Controlled-Release (2
- 6 mg / 6
- 4 mg): Long-term prophylaxis of chronic stable angina pectoris
5. Educational Dosage Context, Formulations & Administration
Educational Dosing & Regimen Summary: General Adult Reference: Sublingual (Acute Angina): Dissolve 1 tablet (0.5 mg GTN or 5 mg Sorbitrate) under the tongue at onset of chest pain; may repeat every 5 minutes up to 3 doses in 15 minutes. Oral CR Prophylaxis: 2.6 mg or 6.4 mg twice daily with an asymmetric 10–12 hour nitrate-free interval (e.g., 08:00 AM and 04:00 PM) to prevent nitrate tolerance. Follow physician prescription.
Administration & Meal Timing: Sublingual: Any time (place under tongue). Oral CR tablets: Swallow whole with water before or after food. | Sublingual: SOS for chest pain. Oral CR BD: Asymmetric schedule (e.g., 08:00 AM and 04:00 PM, rather than 8 AM and 8 PM) to preserve an overnight nitrate-free period so sulfhydryl groups regenerate and prevent nitrate tolerance.
6. Pharmacokinetics, Metabolism & Renal/Hepatic Adjustment
Absorption, distribution, metabolism, and excretion follow class pharmacokinetic profile; verify patient renal/hepatic function.
Renal: No specific dose adjustment required, though monitor blood pressure closely in volume-depleted patients. Hepatic: Extensive hepatic reductase metabolism; use with caution in severe hepatic impairment.
Renal: No specific dose adjustment required, though monitor blood pressure closely in volume-depleted patients. Hepatic: Extensive hepatic reductase metabolism; use with caution in severe hepatic impairment.
Renal: No specific dose adjustment required, though monitor blood pressure closely in volume-depleted patients. Hepatic: Extensive hepatic reductase metabolism; use with caution in severe hepatic impairment.
7. Contraindications, Precautions & High-Risk Warnings
- ABSOLUTELY CONTRAINDICATED within 24 hours of Sildenafil/Vardenafil or within 48 hours of Tadalafil (PDE-5 inhibitors)—causes catastrophic, refractory, fatal hypotension! Also contraindicated in severe anaemia, increased intracranial pressure, right ventricular myocardial infarction, hypertrophic obstructive cardiomyopathy (HOCM), severe aortic stenosis, and systolic BP <90 mmHg.
Key Clinical Precautions: Renal: No specific dose adjustment required, though monitor blood pressure closely in volume-depleted patients. Hepatic: Extensive hepatic reductase metabolism; use with caution in severe hepatic impairment.
8. Adverse Effects Profile
- Throbbing vascular headache ('nitrate headache'—often a sign the tablet is active and potent), facial flushing, orthostatic dizziness, reflex tachycardia, sublingual burning/tingling sensation.
- Profound hypotension, syncope (falling after standing up following sublingual use), rebound angina if chronic high-dose nitrates are stopped abruptly, methaemoglobinaemia (rare, high doses).
- Monitor for severe hypersensitivity, organ toxicity, or dose-limiting adverse events.
9. Major Drug–Drug, Drug–Food & Drug–Herb Interactions
- Fatal Interaction: Sildenafil, Tadalafil, Vardenafil, Avanafil, and Riociguat (synergistic cGMP accumulation causing cardiovascular collapse)
- Additive hypotension with antihypertensives, beta-blockers, CCBs, alpha-blockers (tamsulosin), and alcohol
10. Clinical Monitoring, Patient Counselling & Storage
Clinical & Laboratory Monitoring: Monitor clinical response, baseline renal/hepatic parameters, and relevant serum biomarkers.
Pharmacist Patient Counselling Points:
- Patient Counselling Checklist: The 'Sit & 3-5-15' Sublingual Rule: (1) Always SIT or LIE DOWN before placing a sublingual tablet under the tongue—standing causes fainting as blood pools in the legs. (2) Let it dissolve under the tongue; do not chew or swallow (Oral Nitrocontin CR 2.6/6.4 mg is swallowed whole and is NOT for emergency relief!). (3) If chest pain is not relieved 5 minutes after the first sublingual tablet, take a 2nd tablet and call emergency services immediately (maximum 3 tablets in 15 minutes). Storage Rule: Sublingual GTN tablets are highly volatile and lose potency when exposed to heat, moisture, air, or plastic—keep in the original tightly capped amber glass bottle (no cotton plug inside), away from body heat, and replace 8–12 weeks after opening.
- Meal & Clock Timing Instruction: Sublingual: Any time (place under tongue). Oral CR tablets: Swallow whole with water before or after food. (Sublingual: SOS for chest pain. Oral CR BD: Asymmetric schedule (e.g., 08:00 AM and 04:00 PM, rather than 8 AM and 8 PM) to preserve an overnight nitrate-free period so sulfhydryl groups regenerate and prevent nitrate tolerance.)
- Missed Dose Protocol: For oral CR prophylaxis: take as soon as remembered unless within 6 hours of the next dose (preserve the overnight nitrate-free window). Never double the dose.
- Geriatric Dispensing Pearl: Syncope and hip fractures after taking sublingual nitrates while standing are common in elderly patients. Ensure the patient clearly distinguishes their emergency sublingual tablet (Sorbitrate 5 mg / GTN 0.5 mg) from their daily swallowed prophylaxis tablet (Nitrocontin 2.6 mg).
Storage, Stability & Dispensing Safeguards: Store below 25°C–30°C in original moisture- and light-resistant packaging out of reach of children. Available forms: Sublingual Tablets: 0.5 mg (500 mcg) GTN (or 5 mg Isosorbide Dinitrate SL); Sublingual Spray: 400 mcg/metered dose; Oral Controlled-Release (CR/TR) Tablets/Capsules: 2.6 mg, 6.4 mg
11. Visual Pharmacology & Mechanism Diagram (svg-v339-01-adme-12-step-journey)
12. Authoritative References, Regulatory Sources & Editorial Disclaimer
Primary Compendial & Guideline Reference: Indian Pharmacist Desk Reference — Professional Edition 2.7 (2026–27) • Ch 03 [3.25] (p. 33)
Official Verification Portals: Indian Pharmacopoeia Commission (IPC) & National Formulary of India (NFI) • Central Drugs Standard Control Organization (CDSCO) • Ministry of Health & Family Welfare — NLEM 2022 • NCBI Bookshelf / StatPearls Pharmacology Reference • DailyMed (US FDA Official Prescribing Reference)
Last Medically & Pharmaceutically Reviewed: 2026-11-10 • Verification Status: HANDBOOK_SOURCE_CONTENT
Educational & Clinical Disclaimer: This reference profile is published solely for pharmacy education, academic study, and professional clinical reference. It does not substitute for patient-specific clinical judgement, qualified specialist oncology/medical supervision, or official CDSCO/IP prescribing information. Never self-medicate with prescription, Schedule H/H1/X, NDPS, or oncology medicines.