Working in a similar manner to a transdermal patch, a metered dose transdermal spray (MDTS) delivers a drug to the surface of the skin which is absorbed into the circulation on a sustained basis. 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.
These methods can be used for symptoms of menopause, female androgen insufficiency, severe pain, central nervous system disorders, male androgen insufficiency, urinary incontinence, contraception and smoking cessation. 
- ^ Biotechnology.com