GTN (Glyceryl Trinitrate)

Question 1

Pharmacology and presentation of GTN?

Answer 1

MDI at 0.4mg per spray
50mg patch releasing 0.4mg per hour

GTN is a vasodilator, causing vascular smooth muscle dilation, predominantly working on veins. Results in the formation of Nitric Oxide causing:

• Reduction in preload (venous return), reducing ventricular filling and cardiac output; resulting in reduced myocardial oxygen demand.
• Reduction in afterload caused by arterial dilation leading to reduced peripheral resistance. Reducing the force that the left ventricle overcomes for systemic circulation; which also reduced myocardial oxygen demand.
• Dilation of the coronary arteries, which can increase their blood supply
• Uterine quiescence (CONSULT)

Question 2

Indicators of GTN?
- Triple A Jelly Fish

Answer 2

• Acute Coronary Syndrome
• Acute Cardiogenic Pulmonary Oedema
• Autonomic Dysreflexia (SBP > 160mmHg)
• Irukandji Syndrome (SBP >160mmHg).

Question 3

Contraindications of GTN?

• 4 Hearts, 2x drugs

Answer 3

• Known allergy
• Heart rate <50 (excluding dysreflexia) or >150 BPM
• SBP <110mmHg (Spray) and <90mmHg (Patch)
• Sildenafil Citrate; Vardenafil; Tadalafil in previous 24hrs (PDE5 Inhibitors)
• Ventricular tachycardia
• Inferior STEMI with right ventricular involvement

Question 4

Cautions of GTN?
- ACHE

Answer 4

• CVD, head injuries and CVA
• Risk of hypotension and syncope
• Elderly
• Alcohol intoxication.

Question 5

Side Effects of GTN?

• TD SHH

Answer 5

• Tachycardia or bradycardia
• Hypotension
• Headache
• Skin flushing
• Dizziness or syncope.

Question 6

Dosing Regimes of GTN?

Answer 6

ACS, ACPO, AD, Irukandji Syndrome
- Adult - 0.4mcg (1spray) SL repeating 5 minutely as required, no max dose
- 50mg patch (single dose only)

Question 7

Onset and duration of GTN?

Answer 7

• Onset = <2 minutes
• Duration = 20–30 minutes