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MEDICINE MONOGRAPH CODE: [3.39]-C4 ID: TIP-MED-000274

Isosorbide Dinitrate (ISDN)

Active Ingredient / Scientific Identity: Isosorbide Dinitrate • Class: Long-Acting Organic Nitrate Venodilators / Nitric Oxide Donors (Schedule H | NLEM 2022)

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THE INDIAN PHARMACIST — Educational Reference Sheet
Profile: Isosorbide Dinitrate (ISDN) ([3.39]-C4 | ID: TIP-MED-000274) • Last Reviewed: 2026-11-10
Source URL: https://theindianpharmacist.com/medicine/3-39-c4-isosorbide-dinitrate-isdn/
Generic / Entity NameIsosorbide Dinitrate (ISDN) ([3.39]-C4)
Verified Indian Brands / RefGeneric Compendial Entry (No Commercial Brand Claimed)
Pharmacological ClassLong-Acting Organic Nitrate Venodilators / Nitric Oxide Donors (Schedule H | NLEM 2022)
Available Dosage FormsISMN: 10 mg, 20 mg IR; 30 mg, 60 mg SR/OD Tablets. ISDN: 5 mg Sublingual, 10 mg Oral, 20 mg SR; FDC: ISDN 20 m
Regulatory ClassificationSchedule H Prescription Drug (To be sold by retail on the prescription of a Registere
Key Warning & Review DateRenal & Hepatic: ISMN is active without hepatic first-pass metabolism (100% bioavailable); use lowest starting dose in severe
Reviewed: 2026-11-10
Safety Matrix:⚖️ Legal Status: Schedule H Prescription Drug (To be sold by retail o✔️ Standard Clinical Dispensing Precautions

1. Clinical & Scientific Overview

Isosorbide Dinitrate (ISDN) (TIP-MED-000274, Reference Code [3.39]-C4) is classified under Cardiovascular & Antithrombotic Medicines (Ch 03) as a Long-Acting Organic Nitrate Venodilators / Nitric Oxide Donors (Schedule H | NLEM 2022). 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).

Verified Indian Market Examples / Compendial Status:
Co-indexed constituent under primary monograph [3.39] (Isosorbide Mononitrate (ISMN) & Isosorbide Dinitrate (ISDN)). Representative Indian Market Examples (Edition 2.7 Ch 03 [3.39], p. 40): ISMN: Monotrate / Monotrate OD (Sun), Imdur (AstraZeneca), Nitrocontin. ISDN: Isordil (Abbott), Sorbitrate (Abbott) — Strengths & Dosage Forms: ISMN: 10 mg, 20 mg IR; 30 mg, 60 mg SR/OD Tablets. ISDN: 5 mg Sublingual, 10 mg Oral, 20 mg SR; FDC: ISDN 20 mg + Hydralazine 37.5 mg (Isolazine)
Co-indexed constituent under primary monograph [3.39] (Isosorbide Mononitrate (ISMN) & Isosorbide Dinitrate (ISDN)). Representative Indian Market Examples (Edition 2.7 Ch 03 [3.39], p. 40): ISMN: Monotrate / Monotrate OD (Sun), Imdur (AstraZeneca), Nitrocontin. ISDN: Isordil (Abbott), Sorbitrate (Abbott) — Strengths & Dosage Forms: ISMN: 10 mg, 20 mg IR; 30 mg, 60 mg SR/OD Tablets. ISDN: 5 mg Sublingual, 10 mg Oral, 20 mg SR; FDC: ISDN 20 mg + Hydralazine 37.5 mg (Isolazine)
Dosage Forms & Available Strengths:
ISMN: 10 mg, 20 mg IR; 30 mg, 60 mg SR/OD Tablets. ISDN: 5 mg Sublingual, 10 mg Oral, 20 mg SR; FDC: ISDN 20 mg + Hydralazine 37.5 mg (Isolazine)
Routes: Oral / Parenteral / Topical per formulation

3. Mechanism of Action & Pharmacodynamics

Long-Acting Organic Nitrate Venodilators / Nitric Oxide Donors (Schedule H | NLEM 2022) acting on target receptor/enzyme pathways in Cardiovascular & Antithrombotic Medicines (Ch 03): clinical efficacy is mediated via Long-Acting Organic Nitrate Venodilators / Nitric Oxide Donors (Schedule H | NLEM 2022) for Prophylaxis of chronic stable angina pectoris; adjunct in HFrEF (especially ISDN + Hydralazine in patients intolerant to ACEi/ARB/ARNI). Note: ISDN 5 mg SL is used for acute angina relief; ISMN is NEVER for acute angina attacks!.

4. Therapeutic Indications & Evidence-Supported Uses

  • Prophylaxis of chronic stable angina pectoris
  • adjunct in HFrEF (especially ISDN + Hydralazine in patients intolerant to ACEi/ARB/ARNI)
  • Note: ISDN 5 mg SL is used for acute angina relief
  • ISMN is NEVER for acute angina attacks!

🇮🇳 Jurisdiction & Indication Note: Indications and schedules reflect Indian compendial and regulatory records (CDSCO / Indian Pharmacopoeia & NFI / NLEM 2022). Where international reference labels (US FDA DailyMed / NCBI StatPearls) are cited for pharmacokinetic or mechanistic parameters, international approvals do not automatically imply CDSCO approval in India.

5. Educational Dosage Context, Formulations & Administration

Educational Dosing & Regimen Summary: ISMN SR: 30–60 mg PO OD in the morning (Max 120 mg OD). ISMN IR: 20 mg BD given asymmetrically at 8:00 AM and 3:00 PM (7 hours apart!). ISDN Oral: 10–20 mg BD–TDS with a 10–14h nitrate-free interval

Administration & Meal Timing: Swallow ISMN SR/OD tablets whole after breakfast | Asymmetric Dosing (8:00 AM & 3:00 PM for BD IR; 8:00 AM for OD SR) to guarantee a mandatory 10–14 hour overnight NITRATE-FREE INTERVAL

6. Pharmacokinetics, Metabolism & Renal/Hepatic Adjustment

Absorption & Disposition:
Follows class pharmacokinetic profile detailed in parent monograph [3.39].
Metabolism & Biotransformation:
Renal & Hepatic: ISMN is active without hepatic first-pass metabolism (100% bioavailable); use lowest starting dose in severe hepatic/renal impairment
Elimination & Renal Adjustment:
Renal & Hepatic: ISMN is active without hepatic first-pass metabolism (100% bioavailable); use lowest starting dose in severe hepatic/renal impairment
Hepatic Impairment Considerations:
Renal & Hepatic: ISMN is active without hepatic first-pass metabolism (100% bioavailable); use lowest starting dose in severe hepatic/renal impairment

7. Contraindications, Precautions & High-Risk Warnings

Contraindications & Red-Flag Precautions:
  • ABSOLUTELY CONTRAINDICATED within 24 hours of Sildenafil/Vardenafil or within 48 hours of Tadalafil (fatal refractory hypotension!) and with Riociguat, severe hypotension (<90 mmHg), HOCM, or right ventricular MI

Key Clinical Precautions: Renal & Hepatic: ISMN is active without hepatic first-pass metabolism (100% bioavailable); use lowest starting dose in severe hepatic/renal impairment

8. Adverse Effects Profile

Common & Mechanism-Related Adverse Effects:
  • Nitrate-induced throbbing headache (very common in first 1–2 weeks — treat with Paracetamol, do not stop nitrate!), flushing, postural dizziness
  • Severe syncope, refractory hypotension with PDE-5 inhibitors, nitrate tolerance if dosed 8-hourly around the clock without a nitrate-free window
Serious / Dose-Limiting Adverse Effects:

    9. Major Drug–Drug, Drug–Food & Drug–Herb Interactions

    • PDE-5 Inhibitors (Sildenafil, Tadalafil, Avanafil) = ABSOLUTE CONTRAINDICATION! Additive hypotension with alcohol, antihypertensives, and alpha-blockers

    10. Clinical Monitoring, Patient Counselling & Storage

    Clinical & Laboratory Monitoring: Monitor clinical parameters per parent monograph [3.39].

    Pharmacist Patient Counselling Points:

    • Patient Counselling Checklist: Take twice-daily tablets at 8:00 AM and 3:00 PM (NOT 8:00 AM and 8:00 PM!) so your blood vessels rest overnight and the medicine keeps working; mild headache in week 1 is normal; NEVER take with Sildenafil/Tadalafil
    • Meal & Clock Timing Instruction: Swallow ISMN SR/OD tablets whole after breakfast (Asymmetric Dosing (8:00 AM & 3:00 PM for BD IR; 8:00 AM for OD SR) to guarantee a mandatory 10–14 hour overnight NITRATE-FREE INTERVAL)
    • Missed Dose Protocol: Take if remembered within 4 hours; if late in the evening, skip so the overnight nitrate-free window is preserved
    • Geriatric Dispensing Pearl: Rise slowly from bed or chair to prevent orthostatic falls in older patients

    Storage, Stability & Dispensing Safeguards: Store below 25°C–30°C in original moisture- and light-resistant packaging out of reach of children. Available forms: ISMN: 10 mg, 20 mg IR; 30 mg, 60 mg SR/OD Tablets. ISDN: 5 mg Sublingual, 10 mg Oral, 20 mg SR; FDC: ISDN 20 mg + Hydralazine 37.5 mg (Isolazine)

    11. Visual Pharmacology & Mechanism Diagram (svg-v339-01-adme-12-step-journey)

    THE 12-STEP ORAL DRUG JOURNEY THROUGH THE HUMAN BODY (LADME) Note: IV bolus enters Step 6 directly (F = 100%); Sublingual & Transdermal routes bypass Step 4–5 Portal First-Pass Metabolism 1. Oral Administration • Tablet / Capsule swallowed • Gastric emptying to duodenum pH 1.5–3.5 (Stomach) 2. Disintegration & Dissolution • Tablet breaks into granules • API dissolves in GI fluid Noyes-Whitney Dissolution Rate 3. GI Epithelial Absorption • Crosses intestinal villi • Passive / Active / P-gp efflux Small Intestine (Large Surface Area) 4. Portal Circulation • Mesenteric veins → Portal vein • Delivers blood to liver sinusoids Pre-systemic Venous Conduit 5. First-Pass Metabolism • Gut & hepatic CYP450 extraction • High: GTN, Propranolol, Morphine Determines Bioavailability (F = f_a × (1-E_H)) 6. Systemic Circulation • Hepatic vein → IVC → Heart • Unbound vs Albumin-bound drug Only FREE drug is active 7–8. Tissue Distribution (Vd) • Capillary permeation to organs • Blood-Brain & Placental barriers Vd = Dose / C_0 (L or L/kg) 9. Target Site of Action • Receptors (GPCR, Ion channel) • Enzymes & Carrier Transporters Pharmacodynamic Effect (E_max, EC50) 10. Hepatic Biotransformation • Phase I (CYP450 Oxidation/Hydrolysis) • Phase II (Glucuronidation/Sulfation) Converts lipophilic drug → hydrophilic metabolite 11. Renal & Biliary Elimination • Nephron: Filtration + Secretion − Reabsorption • Biliary excretion & Enterohepatic recycling Total Clearance CL_tot = CL_renal + CL_hepatic 12. Excretion from the Body • Urine (Primary polar metabolite route) • Bile/Faeces, Expired Air, Sweat, Milk Elimination Half-Life t1/2 = (0.693 × Vd) / CL
    svg-v339-01-adme-12-step-journey — 8.1 Complete 12-Step Journey of an Orally Administered Drug (ADME): Figure 8.1: The 12-step physiological journey of a typical orally administered solid dosage form through Liberation, Absorption, Distribution, Metabolism, and Excretion (LADME). Note: Parenteral (IV), sublingual, and inhalational routes bypass gastrointestinal absorption and/or hepatic first-pass metabolism.

    12. Authoritative References, Regulatory Sources & Editorial Disclaimer

    Primary Compendial & Guideline Reference: Indian Pharmacopoeia (IP 2022) • NFI • CDSCO

    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: VERIFIED_EDUCATIONAL_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.

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    Educational Reference Notice: This printout from THE INDIAN PHARMACIST (https://theindianpharmacist.com/medicine/3-39-c4-isosorbide-dinitrate-isdn/, Last Reviewed: 2026-11-10) is an educational reference sheet for students and healthcare learners. It is NOT an official prescribing guideline or patient-specific treatment order.