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Isosorbide mononitrate

Medication nitrate heart & blood pressure
Aka: Imdur, ISMN
Brands seen in Singapore: Imdur, Imdex
Not medical advice. Check with your doctor or pharmacist before you start, stop or change the timing of anything you take.
How to use
What it’s for
Prescribed to prevent angina, not to stop an attack
When to take
SG label: one 60 mg tablet once daily, not twice
Take with
HealthHub: with or without food · not chewed or crushed
Pros & cons
Pros
  • NHS: tablets usually start working within 1 hour
  • SG label: half a 60 mg tablet keeps slow release
  • HealthHub: regular use cuts how often angina hits
Cons
  • NHS: headache, dizziness, weakness are common
  • HealthHub: not with sildenafil, tadalafil, vardenafil
  • NHS: alcohol adds to the dizziness and headache
Sources
  1. HSA — Listing of Registered Therapeutic Products (open dataset on data.gov.sg; same register as HSA Infosearch) · read 2026-08-27
    what it says
    “Only 2 isosorbide-5-mononitrate products on the register, both 'Prescription Only': SIN01996P IMDUR DURULES TABLET 60 mg and SIN10515P IMDEX CR TABLET 60 mg, both film-coated oral tablets, ATC C01DA14.”
  2. MOH National Drug Formulary — IMDUR DURULES TABLET 60 MG [SIN01996P], SG product information (last updated 28 July 2026) · read 2026-08-27
    what it says
    “PRESCRIPTION ONLY MEDICINES … indicated for prophylactic treatment of angina pectoris … not recommended for … acute attacks … One 60 mg Imdur Durules once daily. The dose may be increased to 120 mg once daily … should not be administered twice daily.”
  3. HealthHub (MOH Singapore / Pharmaceutical Society of Singapore) — Isosorbide Mononitrate medication information leaflet (reviewed 10 Apr 2026) · read 2026-08-27
    what it says
    “You may take this medication with or without food. The medication may be halved, but do not crush or chew the tablets … can help to reduce the number of angina attacks … Do not take Sildenafil (Viagra®), Tadalafil (Cialis®), Vardenafil (Levitra®).”
  4. NHS Medicines A-Z — About isosorbide mononitrate and isosorbide dinitrate (reviewed 27 Aug 2024) · read 2026-08-27
    what it says
    “They're used to prevent angina symptoms (chest pain). They do not work to treat a current angina attack … tablets and capsules usually start to work within 1 hour … Drinking alcohol can increase the effects of these medicines.”
  5. NHS Medicines A-Z — How and when to take isosorbide mononitrate and isosorbide dinitrate (reviewed 27 Aug 2024) · read 2026-08-27
    what it says
    “isosorbide mononitrate standard tablets – 10mg, taken twice a day, up to a maximum dose of 120mg a day … slow-release tablets or capsules – 25mg to 60mg, up to a maximum dose of 120mg, taken once a day.”
  6. NHS Medicines A-Z — Who can and cannot take isosorbide mononitrate and isosorbide dinitrate (reviewed 27 Aug 2024) · read 2026-08-27
    what it says
    “tell your doctor or pharmacist if you have: any other heart problems, including a recent heart attack · any recent brain or head injuries · ever had a stroke · an underactive thyroid · low blood pressure · anaemia · glaucoma.”
  7. NHS Medicines A-Z — Side effects of isosorbide mononitrate and isosorbide dinitrate (reviewed 27 Aug 2024) · read 2026-08-27
    what it says
    “common side effects … Headaches … Feeling dizzy, weak, tired or sleepy … Feeling sick (nausea) … Flushing of the face … Do not drink alcohol, as it could make your headaches worse.”
  8. NHS Medicines A-Z — Taking isosorbide mononitrate and isosorbide dinitrate with other medicines and herbal supplements (reviewed 27 Aug 2024) · read 2026-08-27
    what it says
    “medicines for erection problems including sildenafil, avanafil, tadalafil or vardenafil · riociguat … medicines for migraine that contain ergotamine … Do not take non-steroidal anti-inflammatory drugs (NSAIDs) regularly … These may make your angina or heart failure worse.”
  9. FDA / openFDA drug label — Isosorbide mononitrate extended-release tablets (Torrent Pharmaceuticals, effective 11 May 2026) · read 2026-08-27
    what it says
    “The recommended starting dose … is 30 mg … or 60 mg … once daily. After several days, the dosage may be increased to 120 mg … once daily. Rarely, 240 mg may be required … should not be chewed or crushed.”
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Updated 2026-08-29. Every line above traces to a numbered source. Kozen-X is not a medical device and does not give medical advice. It lists what published sources have written down — nothing more. A pair not listed is unrecorded, not cleared. Before you start, stop or re-time anything, talk to your doctor or pharmacist.