Disclosed is a transdermal composition for delivery of diclofenac comprising the use of a pharmaceutically acceptable acid or salt form in an admixture with a pharmaceutically acceptable adhesive matrix carrier. In a preferred embodiment, diclofenac is present as the free acid and potassium salt form in the adhesive matrix composition together with a dual permeation enhancer. The adhesive matrix composition is applied in a method of substantially increasing drug delivery for 24 or more hours.
