I just came through my 2nd hip replacement and I am having severe problems with muscle spasms & involuntary muscle movement's. I have Flexeril 10 mg but it isn't helping me at all and I looked through my medicine and I have some chlorzoxazone 500 mg tablets and I was wondering how much would equal close to a half of a soma because that is what they had to finally put me on after the first surgery. Anybody with any information will be greatly appreciated and thanks in advance for your help and advice on this.