Glyceryl Trinitrate

Question 1

What is the presentation?

Answer 1

Spray bottle containing 200x atomised sprays containing 400mcg per spray

Question 2

What does it do? (6)

Answer 2

Nitrates cause the relaxation of vascular smooth muscle resulting in:

Vasodilation
Peripheral pooling and reduced venous return
Reduced left ventricular and diastolic pressure (preload)
Reduced systemic vascular resistance (afterload)
Reduced myocardial energy and oxygen requirements
Relaxes spasm of coronary arteries

Question 3

What are the indications?

Answer 3

Chest pain/discomfort of presumed cardiac origin not relieved by rest and reassurance with systolic BP > 90mmHg.
Acute Cardiac Pulmonary Oedema with systolic BP >90mmHg.
Autonomic Dysreflexia with systolic BP > 160mmHg.

Question 4

What are the contraindications? (3)

Answer 4

Hypersensitivity
Hypotension < 90mmHg
Medications used for erectile dysfunction within 24 hours (e.g. Sildenafil®, Vardenafil®)

Question 5

What are the precautions? (5)

Answer 5

Nitrates are an early intervention and should not be delayed until on the stretcher or inside the ambulance.
Administer to the patient in a seated or semi-recumbent position.
Do not shake GTN bottle prior to administration.
Assess BP before every dose.
Severe hypotension is an uncommon side effect.

Question 6

What is the dose for cardiac chest pain?

Answer 6

0.4mg (1 spray) sublingually.
If pain persists after 5 minutes and BP maintained, consider further sprays of GTN at 5 minute intervals.
Should the first 3 doses provide some relief but symptoms persist, continue with further doses at 5 minute intervals if no contra-indications.

Question 7

What is the dose for cardiogenic pulmonary oedema?

Answer 7

0.4mg (1 spray) sublingually.
If BP maintained, consider further sprays of GTN at 5 minute intervals.
Should the first 3 doses provide some relief but symptoms persist, continue with further doses at 5 minute intervals if no contra-indications.

Question 8

What is the dose for autonomic dysreflexia?

Answer 8

0.4mg (1 spray) sublingually.

Repeat doses at 5 minute intervals until symptoms resolve or systolic BP < 160mmHg.

Question 9

What are the special considerations/side effects?

Answer 9

Hypotension (rare)
Tachycardia
Flushing
Headache