Methods of producing a transdermal delivery patches are described comprising the preparation of a uniform suspension of drug particles. A plasticizer is added to the suspension. A solution of an adhesive is add to the suspension to form a drug suspension in the adhesive mixture. The drug suspension is coated on a release liner and all solvents are evaporated to form a solid drug reservoir layer. A medical device for transdermal administration of a drug can include the solid drug reservoir layer. Suitable drugs include fentanyl and sufentanil.
