Glyceryl Trinitrate

Question 1

What is the presentation of GTN?

Answer 1

300mcg tablets

Transdermal patch 50mg (0.4mg/hr)

Question 2

What is the pharmacology of GTN?

Answer 2

A vascular smooth muscle relaxant.

Question 3

What are the actions of GTN?

Answer 3

1. Venous dilation promoting venous pooling and reducing venous return to the heart (preload)
2. Arterial dilation, reducing SVR and arterial pressures, reducing afterload.

Question 4

What are the effects of the actions of GTN?

Answer 4

1. Reduced myocardial O2 demand
2. Reduced SBP/DBP/MAP whilst maintaining CPP
3. Mild collateral coronary arterial dilation may improve blood supply to ischaemic areas of the myocardium
4. Mild tachycardia secondary to slight fall in BP
5. Uterine quiescence in the pre-term labour pregnant pt

Question 5

How is GTN metabolised?

Answer 5

By the liver.

Question 6

List the PEI’s for GTN.

Answer 6

1. Chest pain in ACS
2. Acute LVF
3. Hypertension associated with ACS
4. Autonomic dysreflexia
5. Preterm labour (consult only)

Question 7

List the contraindications for GTN.

Answer 7

1. Known hypersensitivity
2. SBP <110 for tablet
3. SBP <90 for patch
4. Sildenafil (Viagra) or Vardenafil (Levitra) in <24hrs, or Tadalafil (Cialis) in <4 days.
5. HR >150bpm
6. Bradycardia of <50bpm exc. autonomic dysreflexia
7. VT
8. Inferior STEMI w/ SBP <160
9. Right ventricular MI

Question 8

List the precautions for GTN.

Answer 8

1. No previous administration
2. Elderly patients
3. Recent MI
4. Concurrent use with tocolytics

Question 9

List the possible routes of admin for GTN.

Answer 9

SL
Buccal
Transdermal
IV infusion (IHT only)

Question 10

List the side effects of GTN.

Answer 10

1. Tachycardia
2. Hypotension
3. Headache
4. Skin flushing (uncommon)
5. Bradycardia (occasionally)

Question 11

List the special notes regarding GTN.

Answer 11

1. GTN susceptible to heat and light - store in original packs.
2. Do not administer pt’s own tablets due to storage concerns/expiry dates.
3. Discard patches before use by date.
4. All pts can be prescribed PDE5 inhibitors - ask both men and women re: C/I’s
5. Tadalafil can be prescribed for benign prostatic hypertrophy (may increase no. pts prescribed it).
6. GTN infusions can be ordered by a doctor for IHT

Question 12

What is the typical dose for a GTN infusion?

Answer 12

5mcg/min - 200mcg/min, increased by 3-5mcg/min.

Accompanied by signed document from Auth. MO.

Question 13

List the onset, peak and duration of S/L GTN.

Answer 13

O: 30s - 2mins
P: 5 - 10mins
D: 15 - 30mins

Question 14

List the onset and peak of transdermal GTN.

*Duration not listed.

Answer 14

O: <30mins
P: 2hrs