L6 - Skin penetration and drug delivery

Question 1

The ______ is the rate determining barrier

Answer 1

SC

Question 2

SC is barrier to water, 70-80% ______ materials. KEEPS WATER OUT

Answer 2

Lipophillic

Question 3

Topical products, want drug to stay in ______ layer

Answer 3

Epidermis

Question 4

Dermis has ____ -> systemic.

Drug delivery here is called

Answer 4

blood vessels

transdermal

Question 5

Ideal drug topical drug properties?

Answer 5

Low molecular weight, balanced logP (1-3),
low melting point,
highly potent,
and not irritant to skin

Question 6

Factors affecting drug permeation - Physiochemical factors?

Answer 6

Molecule size, log P, permeability and diffusion coefficient, solubility, ph and pka

Question 7

Factors affecting drug permeation - Biological factors?

Answer 7

Anatomical site, age, skin hydration, temp, metabolism and pathological condition

Question 8

Factors affecting drug permeation - Formulation factors?

Answer 8

Drug properties, drug conc, drug release, penetration enhancers

Question 9

Transdermal delivery vs topical delivery

Answer 9

Transdermal: designed for delivering the drug past the skin to reach the circulation and exert systemic effect

Topical: Designed to deliver a drug into the skin to treat skin disorders (epidermal or dermal disorders)

Question 10

Enhancement of topical delivery? crossing SC hard..

Answer 10

1. Remove SC w/chemicals
2. Penetration enhancers
3. Advanced dosage form e.g microemulsion

Question 11

Topical drug delivery advangates?

Answer 11

1. Avoids first pass
2. easy application
3. reduced drug dosing (controlled/sustained)
4. Reduced side effects

Question 12

Topical drug deliver disadvantages?

Answer 12

1. not all drugs suitable
2. M in skin
3. Technical difficulties in adhesion
4. skin is strong barrier for drug permeation

Question 13

An example of physical penetration enhancers

Answer 13

Ultrasound = vibration to break skin

Question 14

Chemical penetration enhancers features:

Answer 14

1. reversibly reduced barrier resistance of SC
2. non toxic
3. work rapidly
4. no pharmacological activity

Question 15

Common chemical penetration enhancers

Answer 15

Water, alcohol, urea and surfactants

Question 16

3 Mechanisms of chemical penetration enhancement

Answer 16

1. polarity alteration by surfactant
2. fluidization, destroy bilayyer structure
3. surfactat micelle