GTN Patch

Question 1

GTN - Mechanism of action

Answer 1

GTN is a vasodilator.
GTN causes a reduction in preload to the heart by reducing ventricular filling.It also reduces afterload through arterial dilation which reduces the force the left ventricle must overcome to pump blood to the arteries. This reduces myocardial oxygen demand and blood pressure.

Question 2

GTN - Indications

Answer 2

Cardiogenic pulmonary oedema not rapidly responding to SL.
Hypertension associated with autonomic dysreflexia not rapidly responding to SL.
Hypertension prior to fibrinolytic treatment for STEMI.
Hypertension during inter-hospital transfer for STEMI.

Question 3

GTN - Contraindications

Answer 3

[ABPHRVT]
Known severe allergy.
Systolic BP less than 100 mmHg.
Heart rate less than 40/minute.
Heart rate greater than 150/minute
Ventricular tachycardia.

Question 4

GTN - Cautions

Answer 4

[SPADES]
STEMI, particularly right ventricle STEMI. If low cardiac output then withhold GTN.
Poor perfusion.
Aortic or mitral stenosis.
Dysrhythmia.
Erectile dysfunction drug has been taken in the last 24 hours.
Small, frail, or physiologically unstable patient.

Question 5

GTN - Dosage

Answer 5

Transdermal 10 patch. Releases 0.5mg of GTN per hour.

Question 6

GTN - Common side effects

Answer 6

[2HFTL]
Hypotension.
Flushing.
Headache.
Tachycardia.
Light-headedness.

Question 7

GTN - Onset of effect

Answer 7

10-20 minutes

Question 8

GTN - Duration of effect

Answer 8

18 hours. After patch removal effects fade over 10-20 minutes.

Question 9

GTN - Preparation

Answer 9

Transdermal patch of approx 20cm2 in size.

Question 10

GTN - Repeats

Answer 10

None