Transdermal Drug Delivery Systems

Question 1

Transdermal Drug Delivery Systems (TDDS)

Answer 1

Facilitate the passage of therapeutic quantities of drug substances through the skin and into the general circulation for their systemic effects

Question 2

Transdermal Drug Delivery

Answer 2

API should migrate through the skin to the underlying blood supply without building up in the dermal layers

Question 3

Topical Drug Delivery

Answer 3

API should reside in the skin, which is the target organ

Question 4

Stratum Corneum

Answer 4

10- to 15-µm-thick layer of flat, partially desiccated nonliving tissue

Question 5

Composition of stratum corneum

Answer 5

~40% protein
~40% water
~20% lipid

Question 6

Lipid content

Answer 6

1) is concentrated in the extracellular phase of the stratum corneum and largely forms the membrane surrounding the cells
2) Because a major route of drug penetration is through the intercellular channels, the lipid component is considered an important determinant in the first step of absorption

Question 7

When does drug becomes available for absorption into the general circulation

Answer 7

when it reaches the vascularized dermal layer

Question 8

Advantages of TDDS

Answer 8

1) Bypass hepatic “first-pass” and gastrointestinal incompatibility
2) Reduce side effects due to the optimization of the blood concentration-time profile
3) Provide predictable and extended duration of activity
4) Greater patient compliance due to the elimination of multiple dosing schedules
5) Reversibility of drug delivery

Question 9

Disadvantages of TDDS

Answer 9

1) Only relatively potent drugs are suitable candidates

2) Contact dermatitis

Question 10

TDDS shelf life

Answer 10

up to 2 years

Question 11

TDDS patch size

Answer 11

< 40 cm2

Question 12

TDDS dose frequency

Answer 12

once a day to once a week

Question 13

TDDS aesthetic appeal

Answer 13

clear, tan, or white color

Question 14

TDDS packaging

Answer 14

Easy removal of release liner and minimum number of steps required to apply

Question 15

TDDS skin adhesion

Answer 15

Does not fall-off during dosing

Question 16

TDDS skin reactions

Answer 16

Nonirritating and nonsensitizing

Question 17

TDDS Drug release

Answer 17

Consistent pharmacokinetic and pharmacodynamic profiles over time

Question 18

Factors Affecting Percutaneous Absorption ( listen to lec cap)

Answer 18

1) Drug concentration
2) Area of application
3) Lipophilic:Hydrophilic solubilities
4) Molecular weight
5) Skin hydration, needs to be dry
6) Skin thickness
7) Exposure time

Question 19

Percutaneous Absorption Enhancers: Chemical enhancers

Answer 19

1) increase skin permeability by reversibly damaging or altering the physicochemical nature of the stratum corneum to reduce its diffusional resistance
2) Increased hydration of the stratum corneum
and/or
3) A change in the structure of the lipids and lipoproteins in the intercellular channels through solvent action or denaturation

Question 20

Percutaneous Absorption Enhancers chemical enhancers’ selection is based on?

Answer 20

efficacy, low dermal toxicity and compatibility with other components

Question 21

chemical enhancers example

Answer 21

Acetone
Azone
Dimethyl sulfoxide (DMSO)
Ethanol
Oleic acid
Polyethylene glycol
Propylene glycol
Sodium lauryl sulfate

Question 22

Iontophoresis

Answer 22

delivery of a charged chemical compound across the skin membrane using an electrical field

Question 23

Sonophoresis

Answer 23

high frequency ultrasound to enhance transdermal drug delivery

Question 24

Monolithic systems

Answer 24

1) incorporate a drug matrix layer between backing and frontal layers
2) Drug is dispersed in a matrix layer composed of a polymeric material which controls the rate of drug release

Question 25

Monolithic TDDS matrix preparation

Answer 25

Matrix may be prepared either with or without an excess of drug with regard to its equilibrium solubility and steady-state concentration gradient at the stratum corneum.

Question 26

Monolithic TDDS are designed to contain

Answer 26

an excess of drug and thus have drug-releasing capacity beyond the time frame recommended for replacement ensuring continuous drug availability and absorption as used TDDSs are replaced on schedule with fresh ones.

Question 27

Membrane-Controlled TDDS

Answer 27

contain a drug reservoir or pouch, a rate controlling membrane, and backing, adhesive and protective layers

Question 28

How the release rate of drug through the controlling membrane remains

Answer 28

As long as the drug solution in the reservoir remains saturated

Question 29

Why A small quantity of drug is frequently placed in the adhesive layer ?

Answer 29

to initiate prompt drug absorption and pharmacotherapeutic effects upon placement on the skin

Question 30

If the drug is delivered to the stratum corneum at a rate less than the absorption capacity,

Answer 30

the device is the rate-controlling factor

Question 31

If the drug is delivered to the skin area to saturation

Answer 31

the skin is the rate-controlling factor

Question 32

Absorption

Answer 32

may vary with the site of application.

Question 33

TDDSs should be applied to

Answer 33

clean, dry skin that is relatively free of hair and not oily, irritated, inflamed, broken, or callused

Question 34

Use of skin lotion

Answer 34

should be avoided at the application site.

Question 35

TDDSs should not be physically

Answer 35

altered by cutting.

Question 36

How A TDDS should be removed from its protective package,

Answer 36

with care not to tear or cut into the unit.

Question 37

Place at a site that will

Answer 37

not subject it to being rubbed off by clothing or movement

Question 38

Wear for the full period stated in the product’s instructions

Answer 38

then remove and replace with a fresh system as directed

Question 39

Cleanse hands thoroughly before and after applying a TDDS and do not

Answer 39

rub eyes or touch the mouth during handling of the system

Question 40

if there is sensitivity or intolerance to a TDDS or if undue skin irritation results

Answer 40

Seek reevaluation

Question 41

Used TDDS should be folded in half with the adhesive layer together and reused or not?

Answer 41

not to be reused