During an unscheduled night in A&E (false alarm in the end) the attending junior? cardiologist thought I might be immune to my prescribed Isosorbide mononitrate dose (2x20mg daily) no action was taken at that time and I was discharge with no fault found (again) I'm scheduled to see the team as an out patient in late Nov. So since that night in I've tested my BP pre and post (30 & ~50mins) past a Iso tablet and I have noticed there is no alteration in BP . when I 1st started on these I had noticed a regular 15/10 drop in BP readings so it seems to indicate I could we be suffering from Isosorbide immunity, Has anyone had this occur is it reversible after a time of abstinence? Just pondering the time between now and my next scheduled cardio consultant chat I could just toot on the GTN regularly (joy) . PS the ISO was prescribed as a treatment for possible MVA and not major artery angina as my current stents are patent.
Immune to Isosorbide ?: During an... - British Heart Fou...
Immune to Isosorbide ?
I was told very clearly to take them first thing in the morning, then second dose around 2pm, and not the usual 12hr spacing. The body needs to be clear of them for some hours each day or it will adjust and they will no longer have any effect.
They work on a very quick cycle, and I struggled with the up and down effect, so I now have a single slow release 40mg tablet, which lasts about 10 hours.
Hi BillyMct
I have coronary vasospastic angina, spasms in my microvessels and coronary arteries.
HectorsDad has already mentioned the importance of having a break in nitrates for sometime in 24 hours.
I get most of my pain at rest and in the night so I take my Isosorbide mononitrate extended release 60mgs at 6pm, between 30- 60mgs at 11pm.
I also put on 20 mgs GTN patches at 6pm and remove them in the morning.
In 7 years I have never developed a tolerance to nitrates.
The NICE guidelines have some advice about how to avoid developing nitrate tolerance.
bnf.nice.org.uk/drug/isosor...
Ta for the link, I had thought my consumption was within that guidance range ie there was always a 12hr period between taking the tablets but I'm now wondering if that should be a 12hr period between the effects of the last does and the next one is needed in every 24hr period. for info I started on the 7am and 1pm schedule but found my issues were more likely to occur at rest so swapped to a late evening (post 8pm) and early morning dose. (pre 8am)
My Cardiologist encouraged me to work out the best time to take my nitrates.
I also take my Calcium channel blockers and nicorandil at 8am/ 8pm.
I have to time all my tablets to avoid my blood pressure dropping too much.
It might be worth asking your GP for some GTN patches to use overnight if you are getting pain at rest.
I hope you are more at ease soon!
Actually your dose is not that high and it may need increasing. I think in the weeks before my bypass it reached 80mg! Mind you my LAD was 85% blocked and three others over 75%! ☹️
My dose was low as I tend to run a fairly low (in the acceptable range) BP and they tended to pull that down to the getting in the "a bit low" ranges , though if they aren't doing that now then there could be room for movement. One for my next GP apt chat before my scheduled Cardio out patients slot if they don't cancel 1st (as has happened on prior out patient visits :/ )
I've been asked to take Isosorbide Mononitrate 
RESISTANCE TO GTS UNDER TONGUE SPRAY?
Could I be harming my heart & vascular system with my consistently high BP, despite being on lots of cardiac and BP meds?
Stopping isosorbide mononitrate 
