💊 Isosorbide mononitrate (Isosorbide Mononitrate)
Isosorbide mononitrate is a nitrate medicine that widens blood vessels (arteries and veins). It is used for the prevention and treatment of angina pectoris due to coronary artery disease. It is not useful for stopping an acute angina attack because its onset of action is not rapid enough.
In Arabic: أيزوسوربيد مونونيترات
🏷️ Brand names & manufacturers
Packages shown are US-market (DailyMed). Brands available in Palestine are in the price section below.
Isosorbide Mononitrate🏭 ANI Pharmaceuticals, Inc.
Isosorbide Mononitrate🏭 Torrent Pharmaceuticals Limited
Isosorbide Mononitrate🏭 Genus Lifesciences Inc.✅ What it is used for
- Prevention and treatment of angina pectoris (chest pain) due to coronary artery disease
🧪 Active ingredient
The active ingredient is isosorbide mononitrate, an organic nitrate that relaxes vascular smooth muscle, dilating arteries and veins (especially veins) and reducing the workload of the heart.
🌿 Benefits
- Prevents and treats angina attacks
- Reduces strain on the heart by dilating blood vessels
📝 How to use
- Taken by mouth exactly as prescribed; your doctor or pharmacist sets the dose that is right for you.
- According to the label's general instructions, it is usually given as two doses about 7 hours apart, to provide a daily nitrate-free interval that minimizes the development of tolerance.
- Do not change the dose or timing on your own.
💊 Dosage forms
- 10 mg tablets (white, round, film-coated, scored)
- 20 mg tablets (yellow, round, film-coated, scored)
⚠️ Common side effects
- Headache (most frequent side effect; usually decreases after the first few days of therapy)
- Dizziness
- Nausea
- Fatigue
- Flushing
- Diarrhea and abdominal pain
- Rash and itching
- Cough
🚨 Serious — seek medical help
- Severe low blood pressure or fainting
- Heart rhythm disturbances (slow or fast heartbeat, palpitations)
- Very rarely: methemoglobinemia (a disorder affecting oxygen transport)
- Allergic reaction
⛔ Do not use if
- Allergy to isosorbide mononitrate
- Use with erectile dysfunction drugs that are phosphodiesterase inhibitors, such as sildenafil, tadalafil or vardenafil (can cause severe hypotension, syncope or myocardial ischemia)
- Use with riociguat (can cause hypotension)
❗ Warnings & precautions
- Not for aborting an acute anginal episode, as the onset of action is not sufficiently rapid.
- Benefit has not been established in acute myocardial infarction or congestive heart failure, and use is not recommended there because effects are difficult to terminate rapidly; if used, careful clinical or hemodynamic monitoring is needed to avoid hypotension and tachycardia.
- Sildenafil can amplify the vasodilating effects and cause severe hypotension.
- Tolerance (reduced response) can develop with continuous exposure without a nitrate-free interval.
🔄 Drug interactions
- Phosphodiesterase inhibitors (sildenafil, tadalafil, vardenafil): contraindicated
- Riociguat: contraindicated
- Alcohol: additive vasodilating effect
- Other vasodilators: additive effects
- Calcium channel blockers: marked symptomatic orthostatic hypotension has been reported; dose adjustment of either drug may be necessary
🤰 Pregnancy
Animal studies in rats and rabbits showed no evidence of fetal harm, but there are no adequate and well-controlled studies in pregnant women. Use during pregnancy only if clearly needed and under a doctor's supervision. Birth weight, neonatal survival and development were adversely affected when very high doses were given to pregnant rats in late gestation and lactation.
🍼 Breastfeeding
It is not known whether isosorbide mononitrate is excreted in human milk. Caution should be exercised when it is given to a nursing woman; consult your doctor.
🧒 Children
Safety and effectiveness in pediatric patients have not been established.
👴 Older adults
No dose adjustment is generally necessary in elderly patients, but dose selection should be cautious, usually starting at the low end of the dosing range, because of the greater frequency of decreased hepatic, renal or cardiac function and of concomitant disease or other drug therapy.
🌡️ Storage
Store at 20°C to 25°C (68°F to 77°F). Keep tightly closed.
⏰ Missed dose
The available label text does not give specific instructions for a missed dose; ask your doctor or pharmacist and do not double the dose.
🆘 Overdose
Overdose may cause severe low blood pressure, persistent throbbing headache, confusion, moderate fever, vertigo, palpitations, visual disturbances, nausea and vomiting, fainting, shortness of breath and sweating, and may progress to coma, seizures and death. Seek emergency medical help immediately if overdose is suspected.
💰 Price & brands in your area
🏛️ Official price in Palestine — Ministry of Health price list:
| Product | Company | Pack | Price |
|---|---|---|---|
| VASCOR 40 MG 40 TAB ISOSORBIDE 5 MONONITRATE | BPC | 40 TAB | 22 ₪ |
| MONOCORD 50MG 30 TAB S.R Isosorbide Mononitrate | Alram Drug Store | 30 TAB S.R | 37 ₪ |
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Mechanism of action
Isosorbide mononitrate is the major active metabolite of isosorbide dinitrate. It relaxes vascular smooth muscle, dilating peripheral arteries and veins (especially veins). Venous dilation promotes peripheral pooling of blood and decreases venous return, reducing left ventricular end-diastolic pressure and pulmonary capillary wedge pressure (preload). Arteriolar relaxation reduces systemic vascular resistance and systolic and mean arterial pressure (afterload). Coronary artery dilatation also occurs.
Labeled dosing
The labeled recommended adult regimen is 20 mg twice daily, with doses seven hours apart. A starting dose of 5 mg (half of a 10 mg tablet) may be appropriate for persons of particularly small stature but should be increased to at least 10 mg by the second or third day. No dosage adjustment is necessary for elderly patients or those with altered hepatic or renal function. Doses above 20 mg twice daily have not been adequately studied. The final dose is set by the prescriber.
- The asymmetric two-dose regimen (7 hours apart) provides a nitrate-free interval to minimize tolerance, although some tolerance still occurs.
- Antianginal efficacy begins one hour after the first dose and lasts at least seven hours after the second dose.
- 5 mg twice daily is clearly effective only on the first day of the regimen.
- In overdose: elevate the legs and expand central volume with intravenous normal saline if needed; epinephrine or other arterial vasoconstrictors are likely to do more harm than good.
- Isosorbide mononitrate is significantly removed from the blood during hemodialysis.
🎓 Key points for students
- Isosorbide mononitrate is an organic nitrate with predominant venodilating effects and is the active metabolite of isosorbide dinitrate.
- Nitrate tolerance is avoided with a drug-free interval; the 7-hours-apart regimen leaves a 17-hour gap between the second dose and the next day's first dose.
- It is contraindicated with PDE5 inhibitors and riociguat because of the risk of severe hypotension.
- Headache is the most frequent adverse effect and tends to decrease after the first few days.
- It is not used to abort acute angina because of its slow onset of action.
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Can this medicine stop an acute angina attack?
No. Its onset of action is not rapid enough to abort an acute attack; it is used for prevention and regular treatment as prescribed by your doctor.
Why are the two doses taken seven hours apart?
This gives a daily nitrate-free interval that minimizes the development of tolerance (reduced response). Do not change dose timing unless your doctor tells you to.
Does it cause headaches?
Yes. Headache is the most frequent side effect and usually decreases after the first few days. Tell your doctor if it persists or is severe.
Can I take it with erectile dysfunction medicines?
No. Combining it with sildenafil, tadalafil or vardenafil is contraindicated because it can cause severe hypotension, fainting and myocardial ischemia.
Does alcohol affect this medicine?
Yes. Alcohol has an additive vasodilating effect with this drug, so ask your doctor about its use.
⚕️ For education only — not a substitute for advice from your doctor or pharmacist. Do not start or stop any medicine without advice. Source: official FDA drug label via openFDA (2026-03), simplified. Updated: 2026-11-11.