EMT Pharmacology - GTN

Question 1

Pharmacology and presentation of GTN?

Answer 1

MDI at 0.4mg per spray
TTS 10 patch (50mg patch releasing 0.5mg 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

Answer 2

Spray

• MI
• Cardiogenic Pulmonary Oedema
• Hypertension associated with autonomic dysreflexia
• Control of hypertension with labetalol or metoprolol prior to fibrinolytic treatment in STEMI
• Control of hypertension with labetalol or metoprolol during inter-hospital transfer for STEMI

Patch

• Cardiogenic pulmonary oedema not rapidly responding to spray
• Hypertension associated with autonomic dysreflexia not rapidly responding to spray
• Control of hypertension prior to fibrinolytic treatment in STEMI
• Control of hypertension during inter-hospital transfer for STEMI
• Control of hypertension during inter-hospital transfer for stroke clot retrieval

Question 3

Contraindications of GTN?

Answer 3

• Known Severe allergy
• Systolic BP <100
• HR <40
• HR >150
• VT

Question 4

Cautions of GTN?

Answer 4

• STEMI, particularly Right Ventricle, due to reduction in CO
• Patient small, frail or psychologically unstable
• Poor perfusion, due to reduction in CO
• Dysrhythmia, due to reduction in CO
• Erectile dysfunction medication (PDE5 inhibitors)
• Known Aortic or Mitral Stenosis, due to reduction in CO

Question 5

Side Effects of GTN?

Answer 5

• Hypotension
• Tachycardia
• Flushing
• Headache
• Lightheadedness

Question 6

Dosing Regimes of GTN?

Answer 6

Dosing Regimes for Spray

• MI = 0.4mg every 3-5mins, increase interval to 10min if pt meets cautions
• CPO = 0.8mg every 3-5mins, increase interval to 10min if pt meets cautions and reduce to 0.4mg.
• Hypertension control and A.D = 0.4-0.8mg every 3-5mins

Patch
- Apply if indicated, remove if contraindicated

Question 7

Onset and duration of GTN?

Answer 7

Onset of Spray
‐ 1 to 2 mins

Duration of Spray
- 15 to 30 mins

Onset of Patch
‐ 10 to 20 mins, effect will dissipate over same time frame if patch is removed

Duration
- 18 hours