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Glyceryl trinitrate

Medication nitrate heart & blood pressure
Aka: nitroglycerin, GTN, Nitrolingual
Brands seen in Singapore: Glytrin, Myonit Insta, Rectogesic, Glyceryl Trinitrate-Hameln, Glydex IV
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
HealthHub: to relieve and to prevent angina attacks
When to take
HealthHub: at the first sign of an attack, not later
Take with
HealthHub: under the tongue · the spray is not inhaled
Pros & cons
Pros
  • HealthHub: relief usually comes within five minutes
  • HSA: SG spray and sublingual tablet are pharmacy-only
  • NHS: also works taken before exertion, 1–3 min
Cons
  • HealthHub: headache, flushing, dizziness on standing
  • HealthHub: SG tablets binned 2 months after opening
  • HealthHub: with sildenafil-type drugs, bp can crash
Sources
  1. HSA — Listing of Registered Therapeutic Products (data.gov.sg dataset d_767279312753558cbf19d48344577084), Forensicclassification column; all 5,511 rows cached at /tmp/hsa_all.json and filtered locally (never re-fetched), 5 glyceryl trinitrate / nitroglycerin rows, 27 Aug 2026 · read 2026-08-27
    what it says
    “GLYTRIN SPRAY SIN09161P (400 mcg/spray) and MYONIT INSTA NITROGLYCERIN SUBLINGUAL TABLETS 0.5mg SIN15702P read "Pharmacy Only"; RECTOGESIC OINTMENT 0.2% SIN12240P, GLYCERYL TRINITRATE-HAMELN INJECTION SIN15105P and GLYDEX IV SIN15510P read "Prescription Only"”
  2. MOH National Drug Formulary — GLYTRIN SPRAY [SIN09161P], Product information block (no Indication or Dosing section is published for this licence) · read 2026-08-27
    what it says
    “Active Ingredient and Strength: GLYCERYL TRINITRATE - 400 MCG/SPRAY · Forensic Classification: PHARMACY ONLY MEDICINES · Anatomical Therapeutic Chemical (ATC) code C01DA02”
  3. MOH National Drug Formulary — MYONIT INSTA NITROGLYCERIN SUBLINGUAL TABLETS USP 0.5MG [SIN15702P], Product information block (no Indication or Dosing section is published for this licence) · read 2026-08-27
    what it says
    “DILUTED NITROGLYCERIN USP 5 MG EQV NITROGLYCERIN - 0.5 MG · Forensic Classification: PHARMACY ONLY MEDICINES · Anatomical Therapeutic Chemical (ATC) code C01DA02”
  4. HealthHub (National Medication Information workgroup / Pharmaceutical Society of Singapore) — Glyceryl Trinitrate: what is this medication for · read 2026-08-27
    what it says
    “Glyceryl trinitrate (GTN) belongs to a class of medications called Nitrates. Nitrates are used to prevent and treat the symptoms of angina (chest pain) … Nitrates work by relaxing blood vessels”
  5. HealthHub — Glyceryl Trinitrate: how should I take or use this medication · read 2026-08-27
    what it says
    “The tablet or spray should be used at the first sign of an attack of angina … usually provides relief within five minutes … If you still have pain after using the third tablet … call for an ambulance (995)”
  6. HealthHub — Glyceryl Trinitrate: directions for the sublingual tablets and the mouth spray · read 2026-08-27
    what it says
    “Place a tablet under your tongue when you experience chest pain. Do not swallow the tablet … point the nozzle at the area under your tongue … do NOT inhale the spray.”
  7. HealthHub — Glyceryl Trinitrate: what precautions should I take, and stopping · read 2026-08-27
    what it says
    “You are allergic to this medication or any of the other ingredients … pregnant, planning to become pregnant, or breastfeeding … Stopping your medication suddenly may cause angina attacks.”
  8. HealthHub — Glyceryl Trinitrate: common side effects · read 2026-08-27
    what it says
    “Dizziness, lightheadedness or faintness … more likely to happen if you drink alcohol, stand for a long period of time, exercise or when the weather is hot … Temporary headache … Flushing … Fast heartbeat. Nausea and Vomiting”
  9. HealthHub — Glyceryl Trinitrate: how should I store this medication · read 2026-08-27
    what it says
    “Label the bottle with the opening date when you first open it. Throw the bottle away two months after the date of opening, even if you still have tablets left.”
  10. HealthHub — Glyceryl Trinitrate: what food or medication should I avoid · read 2026-08-27
    what it says
    “When Sildenafil, Tadalafil or Vardenafil is taken with Nitrates, your blood pressure can lower greatly, resulting in dizziness, lightheadedness or fainting. In some cases, death has been reported when Sildenafil was taken with Nitrates.”
  11. NHS medicines A–Z — Glyceryl trinitrate (GTN) (hub page) · read 2026-08-27
    what it says
    “Glyceryl trinitrate (GTN) - Brand names: Rectogesic, Minitran, Glytrin. Find out how glyceryl trinitrate (GTN) treats angina (chest pain) and anal fissures and how to take it.”
  12. NHS medicines A–Z — Glyceryl trinitrate (GTN): how and when to take it · read 2026-08-27
    what it says
    “Do not use more than 2 doses during an angina attack. 1 dose is either 1 tablet or 1 to 2 sprays … 1 tablet under your tongue before you start your activity … 1 to 3 minutes to work.”
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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.