Prokarin (also known as Procarin) is a patented alternative medicine that consists of a mixture of histamine and caffeine. It is marketed as a treatment for multiple sclerosis, but there is no good medical evidence of its safety or effectiveness. The drug lacks any plausible basis in science and is very expensive.
Quackwatch lists Prokarin as one of the multiple sclerosis "cures" that people need to be wary of.
References
Prokarin Wikipedia(Text) CC BY-SA