Nitrates Flashcards
Give 3 examples of nitrates?
- Glyceryl trinitrate (GTN)
- Isosorbide mononitrate (ISMN)
- Isosorbide dinitrate (ISDN)
What is the mechanism of action of GTN?
It is converted to nitric oxide (NO), which causes blood vessels to relax and dilate, so there is a reduction in vascular resistance and more blood is delivered to the body, relieving angina
What are the routes of delivery of GTN?
- Sublingual (tablet or spray)
- Continuous IV infusion
- Transdermal patch
- Ointment (rarely)
What is the indication for GTN spray?
Treatment of angina
What is the indication for ISMN and ISDN?
Prophylaxis of angina
What is the contraindication to nitrates?
Severe aortic stenosis
Why are nitrates contraindicated in severe aortic stenosis?
Vasodilation by nitrate can cause significant drop in blood pressure, which is dangerous in fixed cardiac output states
What might nitrates interact with?
Phosphodiesterase inhibitors, e.g. sildanafil
What monitoring should be done with nitrates?
BP monitoring when GTN given as IV infusion
What should be done if BP drops below 90 with GTN infusion?
Stop, unless advised otherwise
What are the common side effects of nitrates?
- Flushing
- Tachycardia
- Throbbing headaches
- Dizziness
- Postural hypotension
What are the less common side effects of nitrates?
- Nausea
- Syncope
- Tolerance (after prolonged use)
What counselling is required with nitrates?
- Demonstrate GTN spray use
- What to do if chest pain occurs
- Side effects
- Tolerance
What should patients who take GTN tablets be aware of?
Tablets only last for 8 weeks after opening the bottle
What should patients be advised to do if chest pain occurs?
Take GTN spray and ring for ambulance immediately
