Topical/Transdermal Exam 3

Question 1

What are the layers of the skin?

Answer 1

-stratum corneum (most superficial)
-living epidermis
-dermis
-hair follicles and sweat glands

Question 2

Characteristics of stratum corneum

Answer 2

-main barrier to permeation
-“brick and mortar” model
-cells are not permeable
-lipid bilayer
-state of hydration is linked to permeability

Question 3

Characteristics of living epidermis

Answer 3

-does not have capillaries
-get their nutrition from the dermis

Question 4

Characteristics of the dermis

Answer 4

-contains capillaries
-must reach this layer to reach systemic action/produce scarring
-has pain, thermal and tactile sensors

Question 5

Characteristics of hair follicles and sweat glands

Answer 5

-secondary route of drug absorption that bypasses the stratum corneum

Question 6

What are the functions of the skin

Answer 6

-containment
-microbial barrier
-chemical barrier
-radiation barrier
-electrical barrier
-thermal barrier and body temperature regulation

Question 7

Rationale for topical drug delivery

Answer 7

good for surface/localized effects

Question 8

Rationale for transdermal drug delivery

Answer 8

Help with reaching some systemic delivery without having to go through the GI tract (degrades faster in the GI tract)

Question 9

Platforms of topical systems

Answer 9

-ointments
-pastes
-creams
-gels
-rigid foams

Question 10

Different types of ointments

Answer 10

-hydrocarbon base
-silicon bases
-absorption bases
-water soluble bases

Question 11

Examples of hydrocarbon based ointments

Answer 11

petrolatum and polyethylene dissolved in mineral oil

Question 12

Examples of silicone based ointments

Answer 12

contains polydimethylsiloxane oil

Question 13

Examples of absorption based ointments

Answer 13

contains W/O emulsifiers

Question 14

Examples of water soluble bases based ointments

Answer 14

polyethylene glycol ointment (due to it’s good H-bonding)

Question 15

Characteristics of pastes

Answer 15

ointments where high concentration of insoluble particulate solids are added

Question 16

Characteristics of creams

Answer 16

O/W or W/O emulsions

Question 17

Characteristics of gel topical systems

Answer 17

liquid phase trapped in a matrix of a natural or synthetic polymer

Question 18

Examples of hydrogel topical systems

Answer 18

Tragacanth, pectin, carrageenan, methylcellulose, carboxymethylcellulose, carbopol

Question 19

Characteristics of rigid foams

Answer 19

air or gas emulsified in a liquid phase (which may contain the drug)

Question 20

What makes a drug suitable for transdermal delivery

Answer 20

-short systemic half life, undergoes first-pass metabolism
-high logK value
-<1000 Da in MW

Question 21

Factors affecting drug permeability

Answer 21

-hydration
-solubility of drug in the stratum corneum
-excipients (solvents, surfactants)
-pH

Question 22

How does hydration increase drug permeability

Answer 22

increased hydration loosens the lipid packing and makes the bilayer more fluid

Question 23

Methods to improve transdermal drug delivery

Answer 23

-penetration enhancement
-microneedles

Question 24

Iontophoresis

Answer 24

uses LOW voltage electrical current to drive charged drugs through the skin

Question 25

Electroporation

Answer 25

uses HIGH, SHORT to create transient pores in the skin

Question 26

Ultrasound

Answer 26

uses low frequency ultrasonic energy to disrupt the stratum corneum (sonic waves)

Question 27

Prodrugs

Answer 27

modifies the drug structure to make lipophilic

Question 28

Chemical Penetration enhancers

Answer 28

dissolves certain parts of the skin to increase permeability

Question 29

Examples of chemical penetration enhancers

Answer 29

alcohol, DMSO, surfactants, acetone, ethyl acetate

Question 30

Considerations when using chemical penetration enhancers

Answer 30

must rotate sites because if applied it can increase skin wear down and influence dose release rate

Question 31

Dissolving microneedles

Answer 31

-drug polymer matrix -degrades into the skin

Question 32

Hydrogel forming microneedles

Answer 32

-has cross linked hydrogel structure -swells with water and then releases the drug

Question 33

Separable microneedles

Answer 33

-drugs are in the tips of the needles -tips degrade and release the drug

Question 34

Hollow microneedles

Answer 34

-needles are hollow and allow for drug solutions to be injected

Question 35

Potential mistakes patients may make with transdermal patches

Answer 35

-preparation -removal -application -monitoring -storage and disposal

Question 36

What do patients not realize when using transdermal patches

Answer 36

-patch must be applied directly to the skin -must remove protective liner -use one patch at a time -where to place (rotate the area)

Question 37

Drugs in transdermal patches

Answer 37

-nicotine -clonidine -nitroglycerin -estradiol -scoplamine -fentanyl -rivastigmine