NITRATES Flashcards
What are nitrates used for and how do they work?
- They are used to treat Angina and have a role in ACS
- They are vasodilators (dilate blood vessels)
- They work by reducing venous return
Examples
Glyceryl trinitrate (GTN)
- Short-acting
Isosorbide dinitrate
- Long-acting
Isosorbide mononitrate
- Long-acting
What is GTN used for?
- for immediate relief of an episode of angina
- or before activities that are likely to precipitate angina
- Available as sublingual spray or tablets
How should patient’s be counselled on use of GTN for relief of angina?
- ONE DOSE under the tongue on onset of angina symptoms
- ANOTHER DOSE under the tongue if there is no relief 5 minutes after first dose
- Call 999/seek immediate medical attention if no relief 5 minutes after second dose or earlier if patient’s pain is intensifying
DOSE = 1-2 sprays OR 1 tablet
How should GTN S/L tablets be supplied? i.e. packaging
- Glass containers
- No more than 100 tablets in a bottle
- Contain NO cotton wool wadding
- Closed with a foil-lined cap
When should GTN s/l tablets be discarded?
After 8 weeks from opening
Which nitrate provides rapid relief and how long do its effects last for?
Sublingual Glyceryl Trinitrate
It lasts 20-30 minutes
What is one thing you need to be aware of for the GTN transdermal patches formulation specifically regarding the duration of action?
Although they have a longer duration of action, there is a higher risk for tolerance.
What does “tolerance” to nitrates mean?
- When the same dose is not producing the same clinical effect
- So clinic effect is reduced at the same dose
Which formulations of Nitrates can patients develop tolerance to?
How do you limit this?
- Many patients with long-acting nitrates (isosorbide mononitrate or Isosorbide
dinitrate or transdermal) nitrates develop tolerance - Reducing the blood-nitrate concentration to low levels for 4-12 hours a day maintains effectiveness in such patients and reduces tolerance
What if tolerance develops for those who are on
transdermal patches?
- Patches should be left off for 8-12 hours (usually overnight) in every 24 hours
- so every day leave it off at night
Isosorbide dinitrate vs isosorbide
mononitrate
- Active metabolite of isosorbide dinitate is isosorbide mononitrate
- Isosorbide dinitrate can be given sublingually
- dinitrate is ideal for infrequent use
- both are effective by mouth for prophylaxis against angina
- Mononitrate MR preparation e.g. tablets is OD instead of BD
Which has a longer half-life, isosorbide dinitrate or isosorbide mononitrate?
MONO
- Isosorbide mononitrate MR OD
- Isosorbide nitrate MR tablets BD
What if tolerance develops whilst taking modified release isosorbide dinitrate?
- Usually, patients take TWICE daily doses whilst on isosorbide dinitrate MR
- The second dose should be taken about 8 hours after the first dose (rather than 12 hours) to reduce tolerance
Does tolerance occur with MR isosorbide mononitrate?
- NO
- MR Isosorbide mononitrate are mainly given ONCE DAILY (OD)
- If patients take as prescribed then tolerance will not occur
