Exam 2 - Powerpoint 4 (Transdermals)

Question 1

Epidermis

Answer 1

Stratum corner or horny layer is outer most layer

Composed of layers of dead, flattened keratinocytes surrounded by a lipid matrix which acts as a “brick and mortar system”

Question 2

Dermis

Answer 2

Below epidermis

typically between 3-5 mm thick

Blood vessels in dermis distribute drugs into systemic circulation and regulate temps

Question 3

Transdermal Pathways

Answer 3

Transcellular route:
Through cells, lipophilic drugs

Intercellular Route:
Between space between cells, hydrophilic drugs

Question 4

Transdermal Advantages

Answer 4

Controlled release
non invasive
Bypass first pass metabolism
Reduce side effect
Better patient compliance
Maintains desired level well

Question 5

Limitations of Transdermal drugs

Answer 5

Can cause skin irritation, need to change sites

Drugs have to have logP between 1 - 3.5, < 500 MW, highly potent

If logP >5, drug will form depot

Question 6

Transdermal Scop

Answer 6

First TTDS approved 1979

Behind ear due to thin skin and proximity to vein

Question 7

Factors Affecting Percutaneous Absorption

Answer 7

Molecular Weight
Partition coefficient and solubility
Dissociation constant
Nature of vehicle
Skin Condition
Drug Concentration
Surface area
Site of application
Duration of application

Question 8

Things Transdermal drugs have in common

Answer 8

Low molecular weight, well below 400

Small daily doses

Question 9

Basic components of TDDS

Answer 9

Polymer matrix / Drug reservoir
Drug
Permeation enhancers
Pressure sensitive adhesive (PSA)
Backing laminates
Release Liner
Other excipients like plasticizers and solvents

Question 10

Reservoir Types

Answer 10

membrane lies between drug and skin, controls rate of release

provides zero order release as long as drug solution in reservoir remains saturated

Question 11

Matrix Type

Answer 11

drug contained in polymeric matrix

Matrix controlled state of drug release

This type of patch does not provide controlled release

Question 12

Structure Reservoir Type

Answer 12

Backing layer
Drug reservoir
Rate-controlling membrane
contact adhesive
Protective Peel Strip

Skin

Question 13

Structure Matrix controlled

Answer 13

Film backing
Drug/adhesive layer
protective liner

Skin

Question 14

Chemical enhancers

Answer 14

Increase skin permeability by reversibly altering the physical chemical nature of the stratum corneum

Question 15

Nicotine Patch use

Answer 15

Don’t smoke while using
Apply to non-hairy clean area
move to different sites daily
If OD wash with water, no soap

Question 16

Fentanyl Patch use

Answer 16

apply dry, flat area, non hairy
remove old before applying new
do not cut patch
rotate application site

abdomen, upper arm, back, hip and thigh most common