Nitrates

Question 1

Background

Answer 1

Useful in angina
- Potent coronary vasodilator - reduces venous return that reduces left ventricular work.

3 common forms of GTN:
Spray, Patches, Tabs

-Sublingual GTN 1 of most effective drugs in giving rapid symptoms relief BUT effect lasts only 20-30 min

IF use >2/week Long term prophylaxis needed.
- 300mcg Tabs appropriate when GTN 1st used.
Spray is ALT to tabs

Transdermal patches give prolonged action but can develop tolerance to it.

Question 2

AEs

Answer 2

Headaches,
Postural Hypotension
Flushing

Rare - palpitations, syncope

Question 3

GTN Doses (EXAM Q)

Answer 3

Prophylaxis of angina
Sublingual Tabs:
- 1 before activity which can cause angina

Spray:
1-2 doses under tongue

Treatment of angina
(Rule of 3 - take 1 tab if dont work after 5 min try again - do this for 3 doses if dont work then call 999)

Spray:
1-2 doses under tongue

Patches:
One patch every 24 hrs

Routines
- Take B4 exertion
- Take PRN
DOSE usually 1 tab or 1/2 sprays (NB No >3 doses advised at any time)

• Take sitting down to avoid postural hypotension

How to take
- Take 1st dose and wait 5min, 2nd then wait 5 min, 3rd then wait 5 min
THEN CALL 999.

Question 4

Nitrates (isosorbide dinitrates)

Answer 4

I Dinitrate - active sublingually and effective for PTs needing nitrates frequently.

By mouth effective prophylaxis
- Effect persists over several hrs.

Question 5

Dinitrate MR VS Mononitrate MR

Answer 5

Mononitrate MR = OD dose
Dinitrate MR = BD dose

Mono is used more BC di needs to break down in the body when digested and has duration of action of 12 hrs. SO MONO = SHORTCUT

I Mono - given for angina prophylaxis.

IV GTN or IV Iso. Dinitrate - For more SEVERE symptoms OR when Sublingual ineffective.

Question 6

Caution

Answer 6

Constant use of nitrates can lead to your body growing a tolerance and getting used to the dose therefore requiring a stronger dose for the same effect.

TO PREVENT Tolerance:
- Take isosorbide MR OD tabs
- For BD tabs take 2nd dose after 6-8 hrs and not 12
- Leave patch off for 8-12 hrs (usually overnight) each day

[Nitrate free period]
- Taking dinitrate a few hrs earlier gives the body a nitrated free period.
(same applies to patch)

Question 7

Prescribing/Dispensing info (EXAM Q)

Answer 7

Sublingual GTN tabs
Doses 300, 500 & 600mcg

Supply tabs in a glass container no >100 tabs.

Closed with foil line cap

NO cotton wool wadding

Discard after 8 weeks

Rectal ointment should be discarded 8 weeks after opening. (Rectogesic)