Compositions and dosage forms for administering abusable substances are disclosed which have a reduced potential for abuse without diminishing the therapeutic or beneficial effects of the abusable substance. Topical compositions for application to the skin or mucosa contain the abusable substance in a form which is permeable to the skin or mucosa to which it is to be applied and an antagonist for the abusable substance is present in the composition in an abuse negating amount and in a form that is impermeable to the skin or mucosa to which the composition is to be applied. Controlled release dosage forms which release the abusable substance from a drug reservoir composition confined behind a release rate controlling barrier have the abusable substance and its antagonist in the drug reservoir. The abusable substance is present in a form that is releasable from the dosage form and the antagonist is present in an abuse negating amount in a form that is not releasable from the dosage form. Thus the compositions and dosage forms of this invention permit the therapeutic use, at substantially full potency, of an abusable substance when use as prescribed but reduce the abuse potential of the compositions and dosage forms by other routes of administration. Preferred embodiments of the invention utilize fentanyl as the abusable substance and naltrexone as the antagonist in a transdermal dosage form.