A Prodrug is a substance that administered in an inactive or significantly less active form, once metabolized in the body into an active metabolite. There are many ways to introduce the substance into your body, known as a Route of administration. Some examples of prodrugs are Vyvanse, Codeine and Diacetylmorphine. An example of a prodrug is Diacetylmorphine, which when entered into the body, becomes Morphine. To put it simply, A prodrug is a substance that is not active until it is broken down by the body.