The short acting form generally starts working about a half hour after it is given, peaks at 2 hours and is gone at 4 hours. It has a half life of 2-3 hours. It must be taken several times daily to maintain effectiveness.
It comes in 5 mg, 10 mg, and 20 mg tablets. The tablets tend to be bitter, and are best swallowed whole.
Common side effects are headache or stomach ache, usually minimized by taking the
medication after having food.