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Drug Delivery Systems > Transdermal DDS > Flashcards

Transdermal DDS Flashcards

1
Q

What is the main barrier of the Epidermis?

A

Stratum Corneum; prevents endogenous substances and water loss

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2
Q

Shu bi2alba el dermis

A

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

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3
Q

what are keratinocytes

A

Dead cells bl stratum corneum

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4
Q

rate of Diffusion equation

A

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

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5
Q

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

A

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

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6
Q

What are the components of Resistance

A

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

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7
Q

Methods for measuring absorption through skin

A

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

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8
Q

What are the biological factors affecting Drug delivery

A

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

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9
Q

Physicochemical Factors

A

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

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10
Q

What are the approaches used

A

Biochemical
Chemical
Physical
Formulation

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11
Q

Biochemical approach uses what?

A

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

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12
Q

What does the Chemical approach use?

A

Penetration enhancers that temporarily diminishes the impermeability of the skin

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13
Q

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

A

urea (for skin hydration)

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14
Q

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

A

Dimethylsulfoxide (DMSO) and Azones

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15
Q

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

A

Propylene glycol

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16
Q

What are the 3 mechanism Penetration enhancers can act by:

A

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

17
Q

What is an advantage of physical approach

A

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

18
Q

E.g. of problematic drugs:

A

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

19
Q

What are the physical approaches:

A

Stripping SC
Sonophoresis
Electronporation
Iontophoresis
Microneedles

20
Q

How can the SC be removed

A

By the use of adhesive tapes
mechanical dermal abrasion
Laser

21
Q

One disadvantage of SC stripping

A

Costly may cause skin damage

22
Q

What is Sonophoresis

A

Use of ultrasound energy can lead to
Cavitation
Heating

23
Q

What is cavitation and heating

A

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

24
Q

What is Electroporation

A

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

25
Q

What is Iontophoresis

A

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

26
Q

What is Micro needling array

A

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

27
Q

4 types of microneedles

A

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

28
Q

What is formulation approach

A

Uses colloidal carriers i.e nanoemulsions

29
Q

E.g. of colloidal carriers

A

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

30
Q

Transdermal Patches

A

Multilayer polymer based
Two types
matrix and reservoire

31
Q

Matrix Controlled Transdermal Patch Consists of

A

Impermeable occlusive baking layer
Core polymer matrix
Adhesive Layer
Release Liner

32
Q

Impermeable occlusive baking layer

A

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

33
Q

Core polymer Matrix

A

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

34
Q

Adhesive Layer e.g.

A

Polyacrylate
Polyisobutylene
Polydimethylsiloxane
(Prolonged Duration)

35
Q

Release liner e.g.

A

Polyester
Styrene based films
( removed mtl plaster)

36
Q

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

A

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

37
Q

Reservoir Controlled; What does it consist of

A

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

38
Q

When is Reservoir controlled used

A

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

39
Q

E.g. of Marketed Transdermal patches

A

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

Drug Delivery Systems (5 decks)

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