I don't understand why antihistamines work

[catlover11]

I've read alot of information about IC and it seems that antihistamines, like Benadryl, help. How does this help the bladder or lower back from being irritated?

[traceann]

Here's an excerpt on Hydroxyzine from a Q&A:


http://www.ic-network.com/guestlectures/theoharides1205.html

Jill Osborne: Janie asks "What is your opinion of using hydroxyzine and other antihistamines for mast cells?"
Dr. Theoharides: It's an obvious question with a difficult answer. Firstly, in numerous studies about 40-60% of IC patients have some form of allergy or sensitivity. These patients should be taking an antihistamine for that problem alone because any flare up of these symptoms could also effect IC symptoms. However, in IC patients that do not have allergies, typical antihistamines such as Benadryl don't seem to help.
Hydroxyzine is unique because it has four actions. (1) It is an antihistamine, of course. (2) It is also able to reduce anxiety. The word ATARAX is Greek and means to calm down. (3) It also blocks the release of histamine from mast cells (about 30% ). (4) When used in combination with opioid pain killers it creates better pain relief. There are many studies that compared morphine vs. morphine with hydroxyzine for pain or headache. The two used together were better than either one.
So, my initial recommendation for younger, newly diagnosed patients or those that haven't had symptoms more than a year or two, is to start with hydroxyzine at 25 mgs at night and build it up over a few months to 75 mgs at night together with Cystoprotek. If you only take hydroxyzine every now and then, it’s sedating. But if you take it every day, it's far less sedating.
Hydroxyzine is available in pill, capsule or as a liquid elixir. Atarax starts at 10 mgs, Vistaril at 25 mgs and the elixir starts at 5 mgs per teaspoon. As with Cystoprotek, you have to take it for 3 to 4 months. I do not recommend that it be used with anyone who has tremor in their hands because if you take more than 75 mgs per day, sometimes the tremor can get worse.


http://www.ic-network.com/guestlectures/theotranscript.htm

Jill Osborne) Would you describe, briefly, mast cells and what they do?
Dr. Theoharides Mast cells technically belong to the immune system and they come from bone marrow. But, until about five years or so ago, we only thought that they were important for allergic reactions. I sometimes describe the cells to students as soccer balls filled with about 500 ping pong balls. Each ping pong ball contains about 30 important molecules and when these cells are stimulated (i.e. by an allergic reaction, for example) all of those molecules come out along with about ten more which are not inside the ping pong balls. These last ten are known as secretory granules and are made during the reaction.
All of these can cause detrimental effects, such as itching, difficulty breathing, pain, diarrhea, when they are released. In the bladder, they cause pain and inflammation, as well as frequency and urgency because some of the molecules released stimulate the local nerve endings which make you go to the bathroom. In addition, some molecules released act like meat tenderizers and destroy the lining of the bladder and, therefore, create additional problems since the bladder is not protected anymore.
This doesn't mean to say that the mast cell is the beginning and the end of IC but once they get stimulated, they continue to promote all of the problems regardless of what might have been originally the cause. So we took the approach that the best way to reduce IC symptoms, if not hopefully treat, would be to combine some drug that can inhibit mast cells along with something that might help the bladder create new lining.
Seven years ago, our first approach was to use hydroxyzine (aka Atarax or Vistaril) because of the ability of this drug to do four different things.
1. It inhibits mast cells somewhat.. but not 100%
2. It inhibits the activation of local nerves, somewhat.. also not 100%
3. It blocks the neurotransmitter acetydcholine which makes the bladder go – Hydroxyzine is anti-cholinergic like other drugs we use to reduce frequency.
4. It can reduce anxiety.
5. It is sedating so that people who get up at night often can be helped.
Now that doesn't mean that all of the patients will respond to this drug but it was so cheap and we felt we had nothing to lose by starting to use it.
One of the problems from the beginning was (and is) that when physicians hear hydroxyzine, they prescribe patients with a high dose of 100 mgs a day. That dosage would put an elephant to sleep. Instead, what one should do is start a patient at 25 mg at night for a week and usually that sedation goes away within one to two weeks. Then advance the dosage to 50mgs at night and wait 1-2 weeks. That’s a critical point because if the patient still feels sedated after that they should stay at 50. If they aren't very sedated, then they can go to 75mgs. Usually it is 50mgs at night and 25mgs sometime before noon.
The second critical part is that you must stay on the drug for at least 3 months. Many physicians and/or patients don't know this and when they experience a slight sedation, they stop taking it. All they have to do is stick with it at the dose that they can tolerate for a few months. I would say that most of the patients, by six months, will get some relief though it may vary to what extent or symptoms
When the IC trials group was formed by the NIH, they asked for applications from which they would choose the first drug to use in this clinical trial. Our application to compare hydroxyzine to Elmiron was selected. This trial is currently ongoing and all the patients we were aiming to enroll have been enrolled. We should know the results about a year from now. These trials will tell us whether hydroxyzine by itself is effective and whether added to Elmiron, might give us better results. In other words, hydroxyzine compared to Elmiron, and the combination of the two as compared to a sugar pill (placebo).

Hope this helps a little bit as to what's going on and why they seem to work! :)

Hugs,
Tracey

[catlover11]

I wonder if an antihistamine like Alavert would work. I looked at Benadryl and I can't take that during the day because of drowsiness

[traceann]

I also use Zyrtec for my nasal allergies in addition to the Hydroxyzine. I suppose it helps a little bit too, as Dr. Theorides said "However, in IC patients that do not have allergies, typical antihistamines such as Benadryl don't seem to help. " - since I have allergies. I take the Hydroxyzine around 6-7 pm (and for some reason taking it at that time in the evening doesn't make me drowsy either), that way I don't have the groggies the next morning, and I take my Zyrtec right before I turn in. That schedule seems to work really well for me.

I would think it couldn't hurt to try one though, maybe discuss it with your doctor to be on the safe side. And as far at the drowsies, I don't take any of mine during the day - just in the evening and bedtime that way drowsiness side-effects aren't a big problem for me :) Good luck which ever way you decide to go!