Mixed solvent mutually enhanced transdermal therapeutic system

Claim 1

A transdermal drug delivery system comprising (i) an occlusive, impermeable polymeric backing layer; (ii) a drug depot on one side thereof; (iii) a removable, occlusive covering layer over said drug depot; and (iv) an adhesive means by which said delivery system, absent said removable covering layer may be affixed to an intended patient; said drug depot containing a drug formulation comprising a transdermally administrable pharmaceutically acceptable pharmaceutically active agent or a precursor thereof, water and ethanol said active agent or precursor thereof being present in a pharmaceutically effective amount; said ethanol and said water being present in a volume:volume ratio of from 30:70 up to less than 95:5 such that said ethanol, water and drug are delivered to a patient's skin, which patient has applied said system absent said removable covering layer to said patient's skin, in amounts that said drug is delivered in a transdermally administrable efficacious amount, said water has an activity at said patients skin of about 0.4 to about 0.95 and said ethanol, at said patient's skin, has an activity of 0.3 to about 0.9, and wherein, once applied to said patient's skin, said ethanol has a flux from said system to said skin of at least 1500 mcg/cm 2 /hr and through said skin of at least 1500 mcg/cm 2 /hr.