The invention provides a method of sustained delivery of a lactam, imide, amide, sulfonamide, carbamate or urea containing parent drug by administering to a patient an effective amount of a prodrug compound of the invention wherein upon administration to the patient, release of the parent drug from the prodrug is sustained release. Prodrug compounds suitable for use in the methods of the invention are labile conjugates of parent drugs that are derivatized through carbonyl linked prodrug moieties. The prodrug compounds of the invention can be used to treat any condition for which the lactam, imide, amide, sulfonamide, carbamate or urea containing parent drug is useful as a treatment.