mnsr 26

Question 1

transdermal drug delivery is the

Answer 1

delivery of drugs from the skin to the blood by the systemic circulation

Question 2

advantages of TDD

Answer 2

• reduces first pass drug degradation of metabolism effect
• reduces drug side effect ( estriol doesn’t cause liver damage as in oral formulation )
• sustained delivery of drugs ( patches last 1-7 days )
• drugs reservoir remains outside of the body
• allows removal or drug source
• non-invasive ( no needles or injection )
• permits self administration and improves patient compliance

Question 3

disadvantages of TDD

Answer 3

• potential skin irritation
• variability of the doses due to different levels of skin hydration, thickness and anatomical sites
• variation between the patient temp, skin type and skin diseases and age
• poor diffusion ion large and high molecule weight

Question 4

the skin minimises the water loss by

Answer 4

skin has naturally low permabilty to penetration of foreign molecules

Question 5

stratum corundum is

Answer 5

15 nano metre in thickness and has barrier properties

Question 6

the upper dead sublayer of the skin of the epidermis is called

Answer 6

stratum corundum ( from 10-20 um )

Question 7

a sub layer than is devoid from blood vessels

Answer 7

epidermis

Question 8

the lower portion of the skin, contain blood vessels and sweat glands and hair follicle

Answer 8

dermis

Question 9

stratum cornum composed of

Answer 9

vertically stacked coenocyte surrounded by lipid rich matrix.
coenocyte are comprise cross linked keratin fibres ( structural protein ) devoid of lipids
lipid rich matrix serves as primary barrier function. layers of lipids immediately adjacent to each corneocyte is covertly bound to it.

Question 10

the stratum corneum lipids are

Answer 10

20% of SC volume and are assembled into mutli lamellar bilayer.

Question 11

Transdermal transport of solutes is largely controlled by

Answer 11

SC lipid bilayer

Question 12

the two types of transdermal patches

Answer 12

1- reservoir: drug in solution or gel and drug delivery is controlled by the rate-controlling membrane . the control is good and its complex design.
2- matrix type combine drug and adhesive no rate controlling membrane. the skin permeability controls the rate drug delivery. simpler design and less control.

Question 13

Transdermal patches limitation

Answer 13

• low molecular weight required ( less than 500)
• good water and lipid solubility
• neutral rather than ionic drug
• small doses required ( less than 50 mg per day, ideally less than 10mg )
• melting point lower than 100 celsius

Question 14

Penetration techniques enhancement: chemical approach

Answer 14

the use of penetration enhancers, they r combined w drug in transdermal patches

Question 15

penetration enhancers can be

Answer 15

surfactants : surface active agents are usually organic compounds that are amphilatic aka hydrophilic and phobic
fatty acids and esters
solvents (ethanol propylene glycol )

Question 16

the function of penetration enhancers

Answer 16

It increases the skin permeability by:
- enhancing drug solubility
- fluidising structure of startup corneum
- dissolution of stratum corneum lipid

Question 17

Penetration enhancement: physical approach

Answer 17

• improves efficiency of traditional TTD system
• allow delivery of protein-based and dna based therapeutic macromolecules

Question 18

uses electric field to move both charged and uncharged species across the skin

Answer 18

iontophoresis
- low voltage
- long time ( 30 minutes )
- delivery for anti- inflammatory agents , local aesthetic
- can be used in reverse direction to draw a molecule as glucose through the skin
- it increases the skins permeability by the exposure of electric field

Question 19

Iontophoresis enhances transport by 2 different mechanisms

Answer 19

1- electrophotric: driving force: charged molelucles move away from electrode of liked charges
2- elctro- osmotic driving force
. small cationic ions as na are highly mobile
. cation move from anod to cathode
. cations are dissolved associated w layer of water
. cation flux indies a solvent water flow
. uncharged molecules are dragged by electrically induced solvent flow

Question 20

electroporation

Answer 20

• the creation of aqueous pores in lipid bilayer
• application of short micro/milli seconds
• high voltage ( tens to 100s) electric pulse
• electric field indues pores formation by disrupting the lipid bilayer and provides electrophoretic driving force
• large macromolecules can be dilvered as dna proteins and vaccines

Question 21

sonophorseis

Answer 21

ultrasound at frequncies 20khz-16mhz
forms microscopic aqueous channels in lipid bilayer of the intercellular space of the stratum cornuem by the application of ultrasonic waves.
formation of bubbles
can be used to transport high molecular mass drugs ( MW of 1203 as cyclosporin and immucosupression drugs )

Question 22

microneedles

Answer 22

needles of micron dimensions pierces the skin and creates holes large enough for the molecules to enter
the holes r small enough to not penetrate the skin ad cause pain used in:
- pre treatment before application of the patch
- micronnedles coated drugs
- increases permbabitly by order of magnitude for small drugs, large macromolicules and nanoparticles