Transdermal DDS

Question 1

What is the main barrier of the Epidermis?

Answer 1

Stratum Corneum; prevents endogenous substances and water loss

Question 2

Shu bi2alba el dermis

Answer 2

sweat, sebaceous glands, hair fllicles, nerves, blood vessels

Question 3

what are keratinocytes

Answer 3

Dead cells bl stratum corneum

Question 4

rate of Diffusion equation

Answer 4

m=(DKA/d) x (Cd-Cr)-t

Question 5

(DK/d)=1/resistance=Permeability coefficient cm.sec-1

Answer 5

Total permeability= 1/Rvehicle + 1/Rsc + 1/Repi +1/Rdermis

Question 6

What are the components of Resistance

Answer 6

Vehivle, Stratum corneum(aktr shi), Epidermis, dermis

Question 7

Methods for measuring absorption through skin

Answer 7

In vivo blood studies, In vivo clinical efficacy studies, In vitro Human skin or artificial memberane

Question 8

What are the biological factors affecting Drug delivery

Answer 8

Skin condition
Skin age
Regional Skin sites ( behind the ear aktr shi)
Blood flow ( increase bld flow = increase permeation
Skin metabolism

Question 9

Physicochemical Factors

Answer 9

Skin hydration= kl ma aktr kl ma ahsn
Temperature= more fluid more permeable
pH of vehicle= ionized cross aktr
Diffusion Coefficient
Drug concentration
Partition coef
Mioecular size

Question 10

What are the approaches used

Answer 10

Biochemical
Chemical
Physical
Formulation

Question 11

Biochemical approach uses what?

Answer 11

Bio-convertible products (prodrugs) with better permeation profile e.g. theophylline
Also the co administration of skin metabolic products

Question 12

What does the Chemical approach use?

Answer 12

Penetration enhancers that temporarily diminishes the impermeability of the skin

Question 13

E.g. Of penetration enhancer that acts by improving solvent property of SC

Answer 13

urea (for skin hydration)

Question 14

E.g. Of penetration enhancer that acts by Disrupting lipid matrix of SC

Answer 14

Dimethylsulfoxide (DMSO) and Azones

Question 15

E.g. Of penetration enhancer that acts by Promoting partitioning

Answer 15

Propylene glycol

Question 16

What are the 3 mechanism Penetration enhancers can act by:

Answer 16

Improving solvent properties (skin hydration)
Disrupting lipid matrix
Promote partitioning

Question 17

What is an advantage of physical approach

Answer 17

Active transdermal drug delivery used to overcome limitation of previous techniques and deliver problematic drugs

Question 18

E.g. of problematic drugs:

Answer 18

High conc of ionic molecules
Large molecular weight
High doses drugs ( low potency)

Question 19

What are the physical approaches:

Answer 19

Stripping SC
Sonophoresis
Electronporation
Iontophoresis
Microneedles

Question 20

How can the SC be removed

Answer 20

By the use of adhesive tapes
mechanical dermal abrasion
Laser

Question 21

One disadvantage of SC stripping

Answer 21

Costly may cause skin damage

Question 22

What is Sonophoresis

Answer 22

Use of ultrasound energy can lead to
Cavitation
Heating

Question 23

What is cavitation and heating

Answer 23

Cavitation: leads to formation of holes, enlargement of intercellular spaces and perturbations of lipid SC
Heating: increases fluidity of SC and the diffusivity of molecules

Question 24

What is Electroporation

Answer 24

The creation of aqueous pores in the lipid bilayer by the application of short electrical pulses ( micro to millisecond) of large voltage

Question 25

What is Iontophoresis

Answer 25

Charged Molecules (ions) are forced through the SC by the use of small voltage electro repulsion Drug diffusion is proportional to the current density

Question 26

What is Micro needling array

Answer 26

Minimally invasive technique SC is breached without pain using a device consisting of microneedles to insert the drug just below the barrirer without stimulating nerves in deep tissue Deghre btusal aal dermis Flux may increase by 1000 folds

Question 27

4 types of microneedles

Answer 27

Solid removable: Drug free Coated: Medicated; When the needle is inserted into the skin, the coating dissolves and releases the drug into the skin. Coated microneedles are often used for transdermal drug delivery, vaccination, and other medical applications. Dissolving; dissolve in the skin, delivering a drug or other substance as they dissolve Hollow; small hollow channel running through its center. This channel allows a drug or other substance to be delivered directly into the skin, bypassing the outer layers

Question 28

What is formulation approach

Answer 28

Uses colloidal carriers i.e nanoemulsions

Question 29

E.g. of colloidal carriers

Answer 29

Liposomes; 3andon lipid bilayer enclosing aqueous core Nanoemulsion; lipid monolayer lipid cre Solid lipid nanoparticles; lipid monolayer solid lipid core

Question 30

Transdermal Patches

Answer 30

Multilayer polymer based Two types matrix and reservoire

Question 31

Matrix Controlled Transdermal Patch Consists of

Answer 31

Impermeable occlusive baking layer Core polymer matrix Adhesive Layer Release Liner

Question 32

Impermeable occlusive baking layer

Answer 32

non absorptive, printable i.e. Vinyl Polyethylene, polyester Protection and promotes hydration

Question 33

Core polymer Matrix

Answer 33

Contains drug with permeation enhancer to control release i.e. HPMC, polymethylmethacrylate, Eudragit Sustained release

Question 34

Adhesive Layer e.g.

Answer 34

Polyacrylate Polyisobutylene Polydimethylsiloxane (Prolonged Duration)

Question 35

Release liner e.g.

Answer 35

Polyester Styrene based films ( removed mtl plaster)

Question 36

Matrix controlled is thin or thick? What drugs are most appropriate

Answer 36

Thinner that reservoir Appropriate for drugs that penetrate more readily and/or have low dose regimen

Question 37

Reservoir Controlled; What does it consist of

Answer 37

Impermeable occlusive baking layer Reservoirof gel containing drug and permeation enhancer Rate controlling membrane; i.e. microporous PP or PE membrane Adhesive Layer Release Liner

Question 38

When is Reservoir controlled used

Answer 38

used when Matrix system cannot penetrate skin Drug require high penetration enhancement or high dose level

Question 39

E.g. of Marketed Transdermal patches

Answer 39

Clonidine for ADHD Estradiol Fentanyl=Opioid Nicotine for Smoking cessation Oxybutynin= Antimuscarinic for urination control