[proh-druhg] 
| an inactive substance that is converted to a drug within the body by the action of enzymes or other chemicals. |
| pro·drug (prō'drŭg') n. An inactive precursor of a drug, converted into its active form in the body by normal metabolic processes. |
prodrug pro·drug (prō'drŭg')
n.
A class of drugs, initially in inactive form, that are converted into active form in the body by normal metabolic processes.
