Like amphetamine, methylphenidate (MPH) is a chiral compound which is composed of two isomers: d-threo-methylphenidate (also known as dexmethylphenidate, d-methylphenidate, or d-MPH) and l-threo-methylphenidate (also known as l-methylphenidate or l-MPH). Both isomers have the same chemical formula but are mirror images of each other, the same way that a person's hands are the same but are mirror images of each other. Unlike amphetamine, the difference in pharmacological properties between d-MPH and l-MPH is significant, as l-MPH is markedly inferior to d-MPH in its effects, which is due to a number of major differences between the isomers.