Glyceryl Trinitrate

Question 1

GTN -
Contraindications (9)
Precautions (4)

Answer 1

Contraindications:

• BP >110 tablet or >90 patch
• HR >150 or <50 (excluding autonomic dysreflexia)
• hypersensitivity
• erectile dysfunction agent (viagra, levitra past 24h or cialis past 4/7)
• VT
• STEMI with BP <160
• right ventricular infarct (ST elevation in V1, and in lead III > lead II)

Precautions:
# nil prev administration 
# elderly 
# recent MI
# concurrent toxolytic use (to suppress prem labour)

Question 2

GTN - Side Effects (5)

Answer 2

> headache
> tachycardia
> hypotension
> skin flushing (uncommon)
> bradycardia (uncommon)

Question 3

GTN - Actions

Answer 3

A vascular smooth muscle relaxant and potent vasodilator used in:

• acute coronary syndrome
• cardiogenic APO
• autonomic dysreflexia
• pre-term labour (consult only)

Venous dilatation promotes venous pooling and reduces venous return to the heart (thereby reducing preload); arterial dilatation reduces systemic vascular resistance and arterial pressure (thereby reducing after load). The effects of the above are:

• reduced myocardial oxygen demand
• reduced systolic, diastolic and mean arterial blood pressure, while maintaining coronary perfusion pressure
• mild collaterals coronary artery dilatation may improve blood supply to ischaemic areas of myocardium
• preterm labour: promotes uterine quiescence (quietness or inactivity)

Question 4

GTN - Presentation

Answer 4

600mcg tablet

50mg transdermal patch delivering 400mcg/hour

Question 5

GTN - Onset and Duration

Answer 5

S/L/Buccal Effects:

• onset: 30sec - 2mins
• peak: 5 - 10 mins
• duration: 15 - 30mins

Transdermal Effects:

• onset: up to 30mins
• peak: 2 hours