Myasthenia Gravis and Oxybutynin

Andrew Ray aray at emory.edu
Mon Jul 24 23:40:19 EST 1995


In article <3v0j8d$3gkf at ns4-1.CC.Lehigh.EDU>, x011 at Lehigh.EDU writes:

>In article <420402306wnr at tropheus.demon.co.uk>, Steve Wolstenholme 
<steve at trophe
>us.demon.co.uk> writes:
>>About 4 years ago I was showing symptoms of Myasthenia
>>Gravis. My GP was fairly certain of his diagnosis but he
>>sent me for tests just in case. I had various tests
>>including some antibody test (which I can't remeber the
>>name of) and an injection that immediately relieved the
>>facial symptoms and made me feel quite well for a few
>>seconds. The antibody test that was supposed to be a good
>>method of diagnosis proved negative.
>>
>>My symptoms continued to get worse for a month or so but
>>then I ran out of a tablet I was taking for a different
>>problem and I went without them for a few days. The
>>Myasthenia Gravis symptoms dissapeared within a week and
>>they have not returned. The tablets were 5mg Oxybutynin
>>hydrochloride. I no longer take the tablets.
>>
>>Steve Wolstenholme
>>
>Very interesting.  Oxybutynin may be useful as a medicine to
>treat the disease assuming an opponent reaction occurred.
>Ron Blue

I've never heard of oxybutynin (it's probably not on the market in the US), but
since the antibody test was negative, your GP was wrong in his diagnosis of 
Myasthenia Gravis.  However, since a drug that blocks activity at peripheral
nicotinic cholinergic receptors (i.e. at the neuromuscular junction) could 
cause symptoms similar to MG, that would be my "suspect".  Oxybutynin might
do that - if someone knows what it treats, that would be another clue.  If it
blocks cholinergic receptors, that would explain why you're not taking it 
helped the symptoms.  It may actually affect cholinergic metabolism, but it is
doubtful since you didn't mention any other symptoms of loss of cholinergic
function, and since this would probably cause general loss of muscle tone.
As for treating the disease, that would depend on where oxybutynin has its 
activity.

Andrew Ray
Emory University
Dept of Neuroscience
aray at emory.ed



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