1. Now let’s discuss Transdermal Delivery of Drugs
1. Drug molecules diffuse across the skin
2. enter the systemic circulation
3. skin can be a BIG permeability barrier
4. best for drugs with high pharmacological activity (potent)
and good skin permeability (lipophilic)
Nictoine patch

2. Stratus corneum major
resistance for drug
transport
-15 layers of keratinocytes
-space between cells filled
with lipid bilayers

3. 3 issues with diffusion of the drug
1. diffusion in the device or patch
2. diffusion across the SC
3. disposition of drug in underlying tissue
4. distribution of drug throughout the body (PK)

4. Now look at pages and

5. Predicting the permeability of the skin or the SC
Useful for preliminary feasibility calculations in the absence of hard data