transdermal spray transdermal spray a metered-dose transdermal spray (mdts) delivers a drug to the surface of the skin and is absorbed into the circulation on a sustained basis. it works in a similar manner to a transdermal patch or topical gel. the drug is delivered by a device placed gently against the skin and triggered, causing it to release a light spray containing a proprietary formulation of the drug that quickly dries on the skin to form an invisible drug depot. as it would be from a patch, the drug is then absorbed steadily for a predetermined amount of time.