Say, that is an excellent question. I'll look forward to reading the answer, I'm afraid I don't know.

Mestinon can cause weakness in anyone (MG patients as well as nonMGers). The dose at which this occurs can be different for everyone. Here's why (Probably more info than you want).

In normal nerve-muscle junction, nerve fires and releases acetylcholine (Ach) which crosses the junction and attaches to the Ach receptor on the muscle telling the muscle to move. There is an enzyme in the junction that very quickly breaks down the Ach. Usually not a problem because the body releases plenty of Ach to make it to the receptor.

In most cases of Myasthenia, the antibodies have destroyed the receptors so there a fewer and far between. When the nerve releases Ach, it takes longer for the molecule to find a receptor to bind to because there aren't many. Now there is a problem when the enzyme breaks down the Ach molecules before they can find a receptor.

Mestinon works to help Myasthenics because it prevents the enzyme from breaking down the Ach therefore it has more time to find one of the receptors.

If you don't need Mestinon or are taking too much, you can cause too much Ach to be in the junction and this leads to Cholinergic crisis and weakness.

Hope this helps.

Karen

There is never a silly question!!!
Barb,

I agree..As a teacher I always have to encourage many students to ask questions...It is the beginning of knowledge..Thanks .also to the quick response..it was very helpful..Dan

Also I have heard that mestinon can make someone without MG have a positive response. I have heard several doctors say that. Just not as positive as it is in someone who is depleted of acetylholine. If you take the self assesment test for MG for before and after mestinon, if you are one of the people it helps there will be a fair difference. I think they consider 3-5 points significant. Mine was 13. It was truly like a light switch had been flicked and that is rare.But some people with Musk antiodies are not helped as much by mestion and there may be others too with MG who are not helped at all. There are also other ways the neural junction area can have disfunction . We are all snowflakes so no two respond just the same. Marie

It takes a lot of Mestinon for anyone with MG to have a cholinergic crisis. Most younger physicians have never seen one. It occurred primarily during the time the oral Mestinon was the only treatment available under patient control, and patients kept pushing dosages to try and regain function. People who do not have a need for Mestinon would experience side effects with increasing dosage (as opposed to cholinergic crisis) to the extent that they would be unlikely to take those high dosages. The thirty mg once to three times a day given to military as prophylaxis for possible nerve gas poisoning resulted in complaints. Most of the problems with Mestinon at lower dosages,resulting in weakness, are also side effects, such as increased secretions interfering in swallowing and breathing.

Although doctors will comment that other conditions respond to Mestinon, getting a straight answer on which ones? is not usually forthcoming and especially if you ask which ones suspicious for MG would respond. Other conditions cobra bites, nerve gas poisoning, botulism are not easily confused and early response you might see in disease at the nerve side of the junction with poor release of acetylcholine are soon diagnosed on the basis of other findings. As MG progresses the muscle receptors become non functional for a variety of reasons depending on the type of autoimmune problem and Mestinon becomes less effective.

I greatly suspect you are requiring more treatment, not less, and are questioning yourself, your faith in your doctor, and your diagnosis-- that is a good way to get into trouble. Hang in there! b.