Is quinine the active ingredient in tonic water to alleviate leg cramps?

I have always fond it a great way of getting almost instant relief from cramps. Just have a big drink of tonic water made with quinine and the cramp goes. It would be a good idea to find out why you are getting the cramps however. simply taking a mineral supplement or a sports drink prior to or after strenuous exercise can often stop cramps from happening in the first place.