Glyceryl Trinitrate

Question 1

What is glyceryl trinitrate (GTN)?

Answer 1

GTN (400 microg/dose spray) is a potent vasodilator that decreases preload by:
1. Increasing venous capacity
2. Pooling venous blood in the peripheral veins
3. Reducing ventricular filling pressure
4. Decreasing arterial blood pressure (afterload).

GTN is readily absorbed and metabolised by the liver.

Question 2

Indications for GTN?

Answer 2

1. Suspected ACS (with pain)
2. Acute cardiogenic pulmonary oedema
3. Autonomic dysreflexia (SBP >160 mmHg)
4. Irukandji syndrome (SBP >160 mmHg)

Question 3

Contraindications for glyceryl trinitrate?

Answer 3

1. Allergy/ADR
2. Heart rate <50 or >150
3. SBP <100 mmHg
4. Acute CVA
5. Head trauma
6. Phosphodiesterase 5 inhibitor medications
   - Sildenafil or Vardenafil in past 24hrs
   - Tadalafil in the previous 48hrs

Question 4

Precautions for GTN?

Answer 4

1. Inferior AMI
2. Cerebral vascular disease
3. Risk of hypotension and/or syncope
4. Intoxication (GTN effects are enhanced)
5. Phosphodiesterase 5 inhibitor medications
   - Sildenafil or Vardenafil or Tadalafil in past 4 days

Question 5

Side effects of GTN?

Answer 5

1. Dizziness
2. Hypotension
3. Syncope
4. Reflex tachycardia
5. Vascular headaches

Question 6

What is the GTN dose for an adult?

Answer 6

400 microg SUBLING
Repeated at 5 min intervals
No max dose

Question 7

What is the GTN dose for paediatrics with autonomic dysreflexia or irukandji syndrome?

Answer 7

QAS clinical consult required in all situations.