Transdermal Drug Delivery Systems

Front 1

TDDS Percutaneous Absorption

Back 1

Absorption from outside the skin to underneath the skin into the blood stream

Front 2

3 Factors that influence percutaneous absorption

Back 2

1) Physical and chemical properties of the drug (solubility, particle size, pH)
2) Pharmaceutical vehicles/excipeints
3) Condition of the skin

Front 3

Name the skin layers

Back 3

Epidermis
Stratum Corneum (dead cells)
Stratum Lucidum (living epithelium)
Stratum germinativum (living epidermis, basal layer)
Dermis (vascularized, glandular)
Subcutaneous (fatty, injection sites)

Front 4

The Skin of TDDS general characteristics

Back 4

Several layer of epithelial cells at different stages of differentiation covered by emulsified film of sebum, sweat and dead cells

Front 5

Characteristics of the stratum corneum

Back 5

Outer layer (not continuous) composed of non-living cells, film and keratin.

Semipermeable artificial membrane to drug penetration by passive diffusion

Front 6

What is the rate limiting barrier to the transdermal drug transport

Back 6

The stratum corneum layer of the skin

Front 7

What are the 3 transdermal absorptions possible?

Back 7

1) Transcellular for lipid rich non-polar drugs
2) Intercellular for polar drugs, channels for drug penetration
3) Trans-appendigial: minor drug absorption across follicles and glands

Front 8

What are the 4 factors that affect absorption through the skin?

Back 8

1) related to the drug (concentration, particle size, solubility, etc)
2) related to the vehicle (adherence to the skin, miscibility)
3) related to the skin (intact vs broken)
4) related to physical factors (rubbing or exercise for vasodilation and saturation)

Front 9

Chemical methods for percutaneous absorption enhancers

Back 9

reduction of S. corneum's resistance, modification of hydration, modification of lipids in intracellular channels, through carrier mechanism

Front 10

Chemical absorption enhancers: solvents examples

Back 10

water, alcohol, alkyl methyl sulfoxides, pyrrolidones, laurocapram and miscellaneous

Front 11

Amphiphile examples of chemical absorption enhancers

Back 11

anionic surfactants: SDS, docusate sodium
cationic surfactants: quaternary ammonium salts
Amphoteric surfactants: lecithins, cephalins
Nonionic surfactants: mono-, di-, triglycerides
Fatty acids and alcohols: stearyl alcohols, PEG

Front 12

Micellaneous types of chemical absorption enhancers

Back 12

Urea
N,N-dietyhl-m-toluamide

Front 13

2 examples of physical absorption enhancers

Back 13

1) iontophoresis: electrical field
2) sonophoresis: high frequency ultrasound

Front 14

Rate controlling systems intended to: ??? (6 things)

Back 14

1) deliver drug at controlled rate without buildup on dermis
2) release drug prompt into S. corneum for penetration into circulation
3) cause occlusion of the skin for one-way flux of drug
4) non-irritating and non-sensitizing
5) increase patient compliance
6) design must avoid proliferation of bacteria

Front 15

Are patches applied to the same place?

Back 15

No because skin become delicate once patch is removed since skin has been occluded from rough environment and skin can remain saturated

Front 16

Advantages of TDDS (6)

Back 16

1) avoid GI difficulties
2) substitue for oral and parenteral admin
3) avoid first pass effect
4) provide multi-day therapy with single application
5) drug can be terminated by patch removal
6) fast identification during emergencies

Front 17

Disadvantages of TDDS (3)

Back 17

1) unsuitable for irritating and sensitizing drugs or highly sensitive persons
2) only relatively potent drugs can be used in TDDS
3) difficulties in TDDS preparation

Front 18

Monolithic System of TDDS (6)

Back 18

1) continual drug availability through excess drug
2) skin controls rate of absorption of drug (passive diffusion)
3) maintains wide range of plasma concentration over which drug is effective not toxic
4) drug + polymer matrix blended and dried to form gelled matrix
5) gelled matrix assembled between backing and frontal layers
6) prompt release drug in adhesive glue

Front 19

Membrane Controlled System of TDDS

Back 19

1) system controls rate of drug delivery
2) delivers uniform quantities of drug over time
3) drug in the reservoir (liquid or gel) remains saturated and release rate of drug is constant
4) adhesive layer contains prompt release drug
5) backing layer (impermeable) + drug reservoir (liquid or gel) + controlling semipermeable membrane controls drug release per time + adhesive layer with priming dose + protective peel strip
6) SHOULD NOT BE CUT: damage to reservoir

Front 20

Novel Transdermal Systems give 2 examples

Back 20

"not really a patch but penetrates the skin"
1) Omnipod insulin pump with PDM: tubing free, integrated blood glucose meter
2) Finesse Insulin Patch Pen: mechanical, deliver doses of rapid acting insulin by pressing a button a device, capacity is 200 units

Front 21

Drugs in Matrix System (10 examples)

Back 21

1) Estradiol alone and with other hormones
2) Fentanyl (membrane and matrix drugs): iontophoretic matrix delivery
3) Lidocaine and Lidocaine/Tetracaine (oxygen activated heating component)
4) Methylphenidate for ADHD
5) Nicotine
6) Nitroglycerin: must have free interval to decrease tolerability
7) Oxybutynin Chloride for incontinence
8) Rivastigmine for dementia
9) Rotigotine: parkinsons
10) Selegiline - MDD

Front 22

Drugs in Reservoir Systems

Back 22

1) Clonidin
2) Estradiol
3) Fentanyl (c2): duragesic
4) Buprenorphine (C3): moderate chronic pain with opioid analgesic
5) Nicotine (including CQ)
6) Scopolamine for motion sickness: transderm scop
7) Testosterone: andoderm (C3)