GTN

Question 1

Pharmacology and presentation of GTN?

Answer 1

MDI at 0.4mg per spray
50mg patch releasing 0.4mg per hour
50mg in 10ml glass ampoule

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?

Answer 2

• Chest pain associated with ACS
• Hypertension associated with ACS
• Acute Left Ventricular Failure (Pulmonary oedema)
• Autonomic Dysreflexia

Question 3

Contraindications of GTN?

Answer 3

• Hypersensitivity
• Heart rate <50 (excluding dysreflexia) or >150 BPM
• SBP <120mmHg (IV) and <100mmHg (Spray)
• Sildenafil Citrate; Vardenafil (24hrs); Tadalafil in previous 4 days (PDE5 Inhibitors)
• Ventricular tachycardia
• Right ventricular infarct

Question 4

Cautions of GTN?

(ARISEN)

Answer 4

• Always reduce BP slowly rather than aggressively (IV)
• Recent acute MI
• Inferior STEMI with SBP <160
• Avoid skin contact with concentrated solution
• Elderly
• Nil previous administration

Question 5

Side Effects of GTN?

Answer 5

• Skin flushing
• Headache
• Hypotension
• Tachycardia
• Bradycardia

Question 6

Dosing Regimes of GTN?

Answer 6

• ACS & APO = 0.4mg every 5mins, PRN
• A.D = 0.4mg every 10 mins, PRN
• ? increasing interval to 10min if pt meets cautions

Question 7

Onset and duration of GTN?

Answer 7

• Onset = 30 secs - 2 minutes
• Duration = 15–30 minutes