The difference between prodrugs and soft durgs The concepts of prodrugs and soft drugs are opposite, as follow a prodrugs is an inactive compound that requires a meta bolic conversion to the active form a soft drug is pharmacologically active and uses metabolism as a means of promoting excretionThe difference between prodrugs and soft durgs • The concepts of prodrugs and soft drugs are opposite, as follow: • A prodrugs is an inactive compound that requires a metabolic conversion to the active form; • A soft drug is pharmacologically active and uses metabolism as a means of promoting excretion