Page 40 - Pharmaceutics-II (02-06-01 203)

Transdermal drug delivery systems

1. Skin structure and functions
2. Definition of TDDS
3. Rational approach to drug delivery to and via the skin
4. Advantages and disadvantages of TDDS
5. Factors affecting transdermal delivery
6. Criteria for selection of drug candidate for TDDS
7. Drug transport through the skin &routs of penetration
8. Maximizing the bioavailability of drugs applied to the skin

1. Skin structure

The skin has three layers:
1. The epidermis, the outermost layer of skin, provides a waterproof barrier and creates our

skin tone
2. The dermis, beneath the epidermis, contains tough connective tissues, hair follicles, and

sweat glands.
3. The deeper subcutaneous tissue (hypodermis) is made of fat and connective tissues.

https://www.youtube.com/watch?v=ZYBYRIqY9Ps

Skin functions

The skin performs many varied functions:
1. Mechanical function

The dermis provides the mechanical properties of skin, with the epidermis playing a minor part.
2. Protective function (5 main functions)
• Microbiological barrier
The stratum corneum provides a microbiological barrier and the sloughing of groups of
corneocytes with their adhering microorganisms aids the protective mechanism.
skin glands also secrete short-chain fatty acids ………………………………………………
Nitric oxide,
…………………………………………………………………………………………………

39