Antihistamines and PMR

[Specialised]

Hi All,

I was wondering if anyone has any knowledge/experience/comments around the use of antihistamines in the treatment of PMR.

I did read on a post that someone takes a daily antihistamine along with other meds. I have done a little reading online ( not too far down the rabbit hole!!) where Loratadine showed promise as an anti inflammatory drug.

I would be interested to hear if anyone has any experience around this. I have not discussed it with my Rheumatologist yet. I thought I would ask the experts first!😀

Thanks for all your wisdom and knowledge.

Specialised.

[piglette]

Loratadine is an anti inflammatory. I would not have thought it would be much good for a PMR though, unless you had hay fever or an allergy as well. It is in a different drug class to a corticosteroid such as pred.

[Bcol]

Agree with Piglette, that unless you have Hayfever or an allergy of some sort as well as PMR I can't see that it, or an antihistamine, would help at all.

[123-go]

I am sure that if anti-histamines were effective in PMR management they would already be widely prescribed. PMR is an autoimmune disorder not an allergic reaction.

[Specialised in reply to 123-go]

Thanks for your thoughts. I am always looking for something better than steroids to treat this frustrating illness.

I wondered if there was any commonality between allergies and PMR. Both involve our immune system over reacting.

Anyway….fingers crossed that one day there will be a simple effective treatment that can cure the disease.🙏

[DorsetLady PMRGCAuk volunteer in reply to Specialised]

The disease isn’t curable, but it is self-limiting.. and there is a simple effective treatment that manages it… steroids.

[bookish in reply to Specialised]

I should say that I do not have PMR but have other autoimmune conditions. Some people do find that they have increased reactivity alongside autoimmunity and there are links between overactive mast cells and autoimmunity (such as here ncbi.nlm.nih.gov/pmc/articl... ). I have been using mast cell stabilisers for a few years with some benefit, especially magnesium, vit C, ginger, quercetin (watercress, apples, capers), vit D and vit B12 (also an anti-inflammatory). Always worth checking that you don't have another condition or deficiency alongside, confusing the overall picture. Histamine is only one of many chemicals released by trigger-happy mast cells. I found that I reacted to the fillers in antihistamines, which is why I ended up with a food and supplement solution, but I am also aiming upstream, to try to calm the whole reaction, not just the histamine part. Triggers can be wide and varied! Cheers

[krillemy]

I have taken antihistamines daily for up to 3 months at a time due to severe episodes of itching on the tops of my feet and ankles. It helped, and I did not experience any side effects. I don't remember if my PMR symptoms improved, but you never know…

[PMRpro Ambassador]

I have required loratidine for allery problems in the past and took it daily for some years. It did zilch for the PMR.

Antiinflammatories do not all have the same mechanism of action and I think loratidine has a fairly specific mechanism that may work for various end result inflammations by interfering with the pathway much higher up the chain. If that chain is not one involved in PMR - then loratidine is unlikely to do much.

Believe me - if there were a useful cheap alternative to steroids, someone in a biochemistry lab somewhere would have thought of repurposing it!

[AtopicGuy]

I was born atopic and had developed eczema, rhinitis, asthma, hay-fever and several other allergies by my teens. I use 5 or 6 medications every day to keep the symptoms under control, including a double-dose of antihistamines all year round. They have never cured my autoimmunity, they just tone down one little strand of the inflammatory response: the release of histamine that makes tissues leaky, weepy and itchy.

A while ago I came off all my atopy medications for a couple of weeks to see if it made any difference to my CRP and ESR levels. It didn't. All my blood tests remained stubbornly normal, despite the fact my eczema flared up something rotten (see photo). I was so relieved to get back on my usual pills, ointments, eyedrops, nasal spray and inhalers! I taper their usage (especially the amount of steroid cream) so as to just keep the symptoms in remission.

Eczema flare after treatment stopped. CRP and ESR remained normal.

[calibriel]

I’ve been taking Fexafenadine for about 4 months now (in conjunction with another drug) for spontaneous urticaria/andgiodoema: it’s been effective in controlling that, but I haven’t noticed any effect one way or another on the PMR

[PMRnewbie2017]

I wonder if it would help if I explained the pharmacology of anti-histamines and corticosteroids?

Histamine is released in an immune response reaction to an allergen which may be pollen or any number of other things. The histamine released in this situation comes from mast cells and a type of white blood cell called a basophil. The central role of histamine here is itching. Anti-histamines block this response. There are two different types of Histamine receptors - H1 and H2. Drugs which bind to H1 receptors are used to treat allergies. Drugs which bind to H2 receptors are used to treat conditions caused by excess stomach acid. Within the H1 category we have 1st generation and 2nd generation anti-histamines. The first generation anti-histamines (Chlorpheniramine) cross into the brain and therefore cause drowsiness. They are metabolised fairly quickly and are given three times a day. The 2nd generation anti-histamines (Cetirizine, Loratidine, Fexofenadine) do not cross the blood-brain-barrier and have a longer duration of action and have therefore become more popular as they don't cause drowsiness and can be given once a day.

Corticosteroids are synthetic equivalents of natural steroid hormones produced by the adrenal cortex, namely glucocorticoids and mineralocorticoids. We are interested in glucocorticoids and harness their potent ability to have anti-inflammatory effects. The most common corticosteroid in use is Prednisolone. Some countries use Prednisone but this is converted into Prednisolone by the liver. The drug exerts its mode of action on structures deep within the cells and reduces their ability to produce the pro-inflammatory cytokines and other enzymes which are involved in the inflammatory response. In PMR we are interested in Interleukin-6 and it is overproduction of IL-6 which causes the symptoms which we describe as PMR. IL-6 and all of the other cytokines have a really useful purpose and we couldn't survive without them. The problem is, and we don't know why, some of us start churning out too much IL-6 and currently Prednisolone is the only accepted mainstream treatment for PMR. New drugs are being developed, but have restrictions in their use. We refer to PMR as an auto-immune condition because no external allergen is responsible.

Some may say "Ah well I developed PMR after a vaccination", but the vaccine itself didn't cause the PMR. The vaccine creates an immune response to an antigen it contains. The body produces antibodies in response to this. These antibodies will recognise the antigen in future and produce all the substances required to fight the infection. One of these substances will be IL-6 but we cannot predict why in some people the "IL-6 tap" doesn't turn off.

I hope this explains why anti-histamines won't be of use in treating PMR. The 2nd generation anti-histamines do have some some anti-inflammatory effect but it is inflammation associated with histaminic reactions eg insect bites or hayfever.

[PMRpro Ambassador in reply to PMRnewbie2017]

Brilliant - thank you!!!!!!!!!

[tangocharlie in reply to PMRpro]

Can this go in the saved posts? it's really useful even though a bit beyond me as a non-scientist/chemist

[PMRpro Ambassador in reply to tangocharlie]

Not quite as simple as you'd think but I shall confer!

[DorsetLady PMRGCAuk volunteer in reply to tangocharlie]

You can save this post yourself, or just link the reply from PMRnewbie2017 - and keep it in your own records,

[tangocharlie in reply to DorsetLady]

Thanks, I have done, but I can't even find where I've put my glasses so no chance of finding it when I need it again. I tend to copy and paste useful bits I find on here and put them in Word documents, but I've got hundreds of them now

[DorsetLady PMRGCAuk volunteer in reply to tangocharlie]

You need a secretary.. sorry PA nowadays!

[tangocharlie in reply to PMRnewbie2017]

Wow, how do you know all this? Thank you for sharing your knowledge

[PMRpro Ambassador in reply to tangocharlie]

Pharmacy modules in large numbers as a pharmacist!!!!!!

I'm just grateful they wrote it out - I know it too but so nice to have someone else who does and is willing to write the essay

[tangocharlie in reply to PMRpro]

PMRnewbie2017 pretty please could you copy and paste all that info into a separate new post so I can find it again when I need it?

[PMRpro Ambassador in reply to tangocharlie]

Why don't you keep a file of your own? C&P it into a document on your computer

[tangocharlie in reply to PMRpro]

I do but I've got 7 years of saved things now. Just in case I ever write a book lol I find myself shouting at the computer No I don't want to save it in the cloud, I want it on my computer,

[PMRpro Ambassador in reply to tangocharlie]

Yes - but the same thing happens in the FAQs. They get unwieldy and no-one uses them

[DorsetLady PMRGCAuk volunteer in reply to tangocharlie]

You can save it in the cloud, and still have it available on your PC..

[tangocharlie in reply to DorsetLady]

If I ever get round to buying a 'cloud solution'. Anyway I'm digressing far away from the original topic so will shut up or confuse search engines looking for antihistamine posts 😆

[PMRnewbie2017 in reply to tangocharlie]

I know it because i am/ was a Pharmacist. Retired now so I double check my knowledge via Google searches as research improves our understanding and sometimes totally debunks what i was taught 40 years ago!

[tangocharlie in reply to PMRnewbie2017]

Aha, thought you must be a medical professional you gave such a good answer. I see from the name you got PMR in 2017, has it gone now or where are you at with it?

[Specialised in reply to PMRnewbie2017]

Thank you for the explanation. Am glad I asked the question. Every bit of information helps to understand how this condition works.

Cheers,

😀

[tangocharlie in reply to Specialised]

A final thought, you might have read that some of us take an anti-histamine of the H2 blocker kind and this also does the job of protecting the stomach so I don't need to take Omeprazole

[Mfaepink1973 in reply to PMRnewbie2017]

Thanks so much for your very clear explanation

[tangocharlie]

I take Cimetidine once or twice daily but that's for the strange reactions I get to loads of different foods which I think are probably a mast cell reaction to histamine overload, but I can't get anyone to confirm if that is the case so it's just self-diagnosis, albeit the Cimetidine was prescribed originally by a bladder consultant and endorsed by Immunology. It acts as a histamine blocker so stops gut, stomach bladder, skin and other reactions. I think it's possible that as it works to block reactions in that respect because it does the same job as the steroids would do for 'dampening down' reactions but never really thought more about it than that. I noticed it a few years ago now. I was on a high dose of steroids and everything was under control and ticking along nicely. Then I reduced the dose of steroids and loads of other non-PMR symptoms surfaced. It doesn't take the place of Pred when it comes to inflammation from PMR.

[PMRnewbie2017 in reply to tangocharlie]

It works because Cimetidine is a Histamine H2 antagonist. I prefer H2 antagonists to PPIs for controlling stomach acid production because they have fewer side effects and for us steroid takers don't cause issues with calcium absorption and hence possible osteopenia/porosis. Unfortunately since Ranitidine (H2 antagonist) was withdrawn, PPIs have become the "go to" drug for most prescribers.

[tangocharlie in reply to PMRnewbie2017]

Yes I used to use Ranitidine it worked fine and you could easily buy it OTC but now that's withdrawn I have to get the Cimetidine prescribed and it is often hard to get hold of. Must be better for people than Omeprazole though as that's only really meant for short term use isn't it, not for use for years as a stomach protector. Did yo see the talk by Christian Selinger at the online AGM, he said you probably don't need if if your're on low doses of steroids anyway.

[PMRnewbie2017 in reply to tangocharlie]

TBH, I took Lansoprazole initially when i was taking 30mg Pred for ?GCA. After a couple of weeks I stopped it once I developed side effects. Plus I didn't want the problem of impaired calcium absorption as I refused alendronic acid. I've never taken any so called stomach protectors save for an odd gulp of Gavisco. If I get heartburn it's usually from a very spicy curry!