Isordil (Isosorbide Dinitrate) Dosage Guide in Pakistan

Both the correct dosage and timing for Isordil are essential. An overnight nitrate-free interval MUST be maintained to avoid nitrate tolerance. This guide explains oral and sublingual dosing along with the asymmetric dosing rule.

Compiled by the PakVita Editorial Team · AI-assisted drafting with editorial review · Sourced from DRAP, WHO, BNF · Last updated: 2026-06-17

Dosage Guide

Quick Answer

Isordil (ISDN) oral prophylaxis requires multiple daily doses with a mandatory nitrate-free interval (10-12 hours overnight) — asymmetric dosing is essential. The sublingual 5mg tablet is placed under the tongue for acute angina — taking effect in 2-5 minutes. Always follow the doctor's prescription strictly.

Dose at a Glance

Adult Dose

Oral prophylaxis: as per doctor's guidance (multiple daily doses); Sublingual: 5mg under tongue for acute angina

Multiple daily doses with overnight nitrate-free interval (asymmetric dosing)

Max: As per doctor's prescription — do not increase dose yourself

Child Dose (Adults only (general))

Not generally used in children — specialist guidance required

N/A

Missed Dose

If you miss a dose, take it as soon as you remember. If the next dose is close, skip the missed dose. Never take a double dose. Do not disrupt the nitrate-free interval schedule.

Overdose

Overdose may cause severe hypotension, headache, flushing, and loss of consciousness. Contact emergency services immediately. Nitrate overdose combined with a PDE5 inhibitor is particularly dangerous.

Isordil (Isosorbide Dinitrate) Dosage (Kitni leni hai)

Isordil (ISDN) dosing has two important rules: (1) always follow your doctor's prescription strictly, and (2) maintain an overnight nitrate-free interval to avoid nitrate tolerance.

THE MOST IMPORTANT DOSING RULE — NITRATE-FREE INTERVAL

If Isordil is taken at the same intervals around the clock → tolerance develops → the medicine becomes less effective.

Solution: Asymmetric Dosing

Correct: 8AM + 1PM (overnight nitrate-free window of ~19 hours)
Wrong: 8AM + 8PM (only 12-hour gap — insufficient)
Always follow the specific schedule given by your doctor

Adult Dose — Oral Prophylaxis

As per your doctor's prescription — typically starting at 10mg-20mg, titrated
Multiple daily doses — asymmetric schedule is essential

Adult Dose — Sublingual (Acute Angina)

1. Sit or lie down when an angina attack occurs 2. Place the 5mg tablet UNDER the tongue — do not swallow it 3. It dissolves in 2-5 minutes — relief should follow 4. If no relief after 5 minutes → take a 2nd tablet 5. If still no relief after 15 minutes (3 tablets) → CALL EMERGENCY SERVICES (ambulance) IMMEDIATELY

First Dose Precaution

After the first dose, sit or lie down — blood pressure may drop
Headache is normal — paracetamol can be taken

Missed Dose

Take it as soon as you remember. If the next dose is close, skip the missed dose. Do not disrupt the nitrate-free interval schedule. Never take a double dose.

Dose Summary Table

Use	Route	Dose	Notes
Angina prophylaxis	Oral	As per doctor's guidance — multiple daily doses	Asymmetric dosing — overnight nitrate-free interval required
Acute angina	Sublingual	5mg under tongue	No relief after 3 doses → EMERGENCY

The information in this guide is for educational purposes only. Always confirm the dose with your doctor or pharmacist.

Frequently Asked Questions

Isordil ki dose kya hoti hai?

For oral prophylaxis, follow your doctor's prescription — multiple daily doses with an overnight nitrate-free interval (asymmetric dosing). The sublingual 5mg tablet is used for acute angina.

Nitrate-free interval kya hota hai aur kyun zaroori hai?

If Isordil remains continuously in the blood for 24 hours, tolerance develops — the medicine becomes less effective. A 10-12 hour nitrate-free interval (usually overnight) prevents this. Asymmetric dosing (8AM + 1PM — NOT 8AM + 8PM) ensures this interval is maintained.

Sublingual Isordil kaise use karte hain?

Place the 5mg tablet UNDER the tongue — do not swallow it. Sit or lie down. It dissolves in 2-5 minutes — relief should follow. If no relief after 5 minutes, take a 2nd tablet. If no relief after 3 tablets (15 minutes) — call emergency services immediately.

Kya isordil khali pait leni chahiye?

Oral tablets can be taken with or after food. The sublingual tablet is taken at any time — immediately when an angina attack occurs. After the first dose, sit or lie down.

Isordil lene ke baad sar dard kyon hota hai?

Headache is the most common side effect of the nitrate class — it is more frequent in the first 1-2 weeks. This is normal and usually improves with continued use. It can be managed with paracetamol.

Brand alternatives, same-class options, and other medicines used for the same conditions as Isordil Tablet.

Used for the same conditions

Other medicines commonly used for stomach pain (abdominal pain) and overlapping conditions.

Stomach Pain (Abdominal Pain) hub →

Sources

DRAP Registered Products Database — Drug Regulatory Authority of Pakistan
WHO Model List of Essential Medicines, 23rd ed. (2023) — World Health Organization
British National Formulary (BNF) — BMJ Group & Pharmaceutical Press

Medical disclaimer

This page is for educational use only and does not replace professional medical advice. Always confirm diagnosis, dose, and interactions with a qualified doctor or pharmacist before starting or changing any medicine.