What is the presentation of GTN?
300mcg tablets
Transdermal patch 50mg (0.4mg/hr)
What is the pharmacology of GTN?
A vascular smooth muscle relaxant.
What are the actions of GTN?
- Venous dilation promoting venous pooling and reducing venous return to the heart (preload)
- Arterial dilation, reducing SVR and arterial pressures, reducing afterload.
What are the effects of the actions of GTN?
- Reduced myocardial O2 demand
- Reduced SBP/DBP/MAP whilst maintaining CPP
- Mild collateral coronary arterial dilation may improve blood supply to ischaemic areas of the myocardium
- Mild tachycardia secondary to slight fall in BP
- Uterine quiescence in the pre-term labour pregnant pt
How is GTN metabolised?
By the liver.
List the PEI’s for GTN.
- Chest pain in ACS
- Acute LVF
- Hypertension associated with ACS
- Autonomic dysreflexia
- Preterm labour (consult only)
List the contraindications for GTN.
- Known hypersensitivity
- SBP <110 for tablet
- SBP <90 for patch
- Sildenafil (Viagra) or Vardenafil (Levitra) in <24hrs, or Tadalafil (Cialis) in <4 days.
- HR >150bpm
- Bradycardia of <50bpm exc. autonomic dysreflexia
- VT
- Inferior STEMI w/ SBP <160
- Right ventricular MI
List the precautions for GTN.
- No previous administration
- Elderly patients
- Recent MI
- Concurrent use with tocolytics
List the possible routes of admin for GTN.
SL
Buccal
Transdermal
IV infusion (IHT only)
List the side effects of GTN.
- Tachycardia
- Hypotension
- Headache
- Skin flushing (uncommon)
- Bradycardia (occasionally)
List the special notes regarding GTN.
- GTN susceptible to heat and light - store in original packs.
- Do not administer pt’s own tablets due to storage concerns/expiry dates.
- Discard patches before use by date.
- All pts can be prescribed PDE5 inhibitors - ask both men and women re: C/I’s
- Tadalafil can be prescribed for benign prostatic hypertrophy (may increase no. pts prescribed it).
- GTN infusions can be ordered by a doctor for IHT
What is the typical dose for a GTN infusion?
5mcg/min - 200mcg/min, increased by 3-5mcg/min.
Accompanied by signed document from Auth. MO.
List the onset, peak and duration of S/L GTN.
O: 30s - 2mins
P: 5 - 10mins
D: 15 - 30mins
List the onset and peak of transdermal GTN.
*Duration not listed.
O: <30mins
P: 2hrs
