TRANSDERMAL DRUG DELIVERY SYSTEM B. PHARM 7TH SEM UNIT 3RD NOTES BY SHWETA PATEL ASSITANT RPOFESSOR UNIT 3 PPT OF B. PHARM 7TH SEM.pdf

TDDS (Transdermal Drug Delivery System) notes.
Including the following two diagrams will make your notes complete and visually clear:

Labeled diagram of the skin – showing Stratum corneum, Epidermis, Dermis, Sweat glands, Hair follicles, and blood vessels.
→ Helps explain permeation pathways and skin structure.

Structure of a Transdermal Patch – showing layers such as:

Backing layer

Drug reservoir or matrix

Rate-controlling membrane (if applicable)

Adhesive layer

Release liner

1. TRANSDERMAL DRUG
DELIVERY SYSTEMS
Unit: III
SUBJECT NAME: NOVEL DRUG DELIVERY SYSTEM
BP-704T
B Pharm VII Semester
SHWETA PATEL
IIMT COLLEGE OF
PHARMACY NOIDA
(Assistant Professor)
PART -1
ST
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2. COMPONENTS-
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1.INTRODUCTION PART OF TDDS
2.ADVANTAGE OF TDDS
3.DISADVANTAGE OF TDDS
4.SKIN STRUCTURE
5.ROUTS OF DRUG PERMEATION
6.FACTORS AFFECTING PERMEATION THROUGH SKIN
7.PHYSIOLOGICAL FACTOR OF DRUG
8.FORMULATION FACTORS
9.Permeation Enhancers
10.EXAMPLES OF PERMEATION ENHANCERS
11.BASIC COMPONENTS OF TDDS
12.FORMULATION APPROACHES OF TDDS
13.EVALUATION OF TDDS
14.IDEAL DRUG CANDIDATES FOR TDDS
15.APPLICATIONS OF TDDS
16.Future Perspectives
17.SUMMARY TABLE: KEY CONCEPTS
18.REFERENCES

3. INTRODUCTION PART OF TDDS
1.Introduction
Definition:
TransdermalDrugDeliverySystem(TDDS)isadosageformdesignedtodeliverdrugsthroughtheskin(transdermalroute)intothe
systemiccirculationatacontrolledrate.
Itbypassesthegastrointestinaltractandfirst-passhepaticmetabolism,offeringanon-invasive,controlled,andpatient-compliant
methodfordrugadministration.
Examples:
Nitro-Dur®(Nitroglycerin)
Catapres-TTS®(Clonidine)
TransdermScop®(Scopolamine)
Nicoderm®(Nicotine)
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4. ADVANTAGES OF TDDS
Avoids first-pass metabolism(increased bioavailability).
Prolonged and controlled drug release(steady plasma levels).
Improved patient compliance(non-invasive, less frequent dosing).
Reduced side effectsdue to avoidance of peak-trough fluctuations.
Easy terminationof therapy (patch removal).
Suitable for drugs with short half-livesor poor oral absorption.
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5. DISADVANTAGE OF TDDS
Disadvantages
Limited to potent drugs(dose < 10 mg/day).
Skin irritation or sensitizationpossible.
Variable skin permeabilityamong individuals.
Slow onset of action.
Difficult formulation designfor hydrophilic drugs.
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6. 2. SKIN STRUCTURE
The skinis a multilayered barrier—the main site of drug absorption in TDDS.
Layers of Skin
Stratum Corneum(SC)–Outermost, ~10–20 µm thick, made of keratinized cells embedded in
lipid matrix (“brick and mortar” model).
◦Primary barrierto permeation.
Viable Epidermis–Living cells; no blood supply; acts as a secondary barrier.
Dermis–Contains blood vessels, lymphatics, and nerves; once the drug reaches dermis, it
enters systemic circulation.
Subcutaneous tissue–Fatty layer, mainly for insulation and cushioning.
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7. SKIN STRUCTURE
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8. ROUTES OF DRUG PERMEATION THROUGH
SKIN
Drugs can penetrate the skin by three main pathways:
Transcellular (through cells):
◦Drug passes through corneocytes(keratin-filled cells).
◦Favored by lipophilic and small molecules.
Intercellular (between cells):
◦Drug diffuses through lipid matrix around corneocytes.
◦Main route for lipid-soluble drugs.
Appendageal(via appendages):
◦Through sweat glands or hair follicles.
◦Minor route (<0.1% of total area), but useful for ions or large molecules.
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9. ROUTES OF DRUG PERMEATION THROUGH
SKIN
Based on diagram
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10. 3. FACTORS AFFECTING PERMEATION THROUGH SKIN
Factor Effect on Permeation
Skin thickness
Thinner skin (eyelids) → higher permeation; thicker
skin (soles) → low permeation
Age
Elderly: decreased hydration; Infants: higher
permeability
Skin hydration Increases permeability (hydrated SC is more flexible)
Skin temperature
Increased temperature → enhanced diffusion &
blood flow
Skin metabolism
Enzymes in skin may metabolize drugs before
absorption
Site of application Variation in lipid content & blood flow affects rate
Diseases Psoriasis, eczema can increase permeability
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11. PHYSIOLOGICAL FACTOR OF DRUG
Property Effect
Molecular weight Ideal < 500 Da for passive diffusion
Partition coefficient (log P)
Optimal between 1–4 for balanced lipid-water
solubility
pKaand ionization Unionized form favors absorption
Solubility
Should have adequate solubility in both lipid and
aqueous phases
Polymorphism Different crystal forms affect solubility and diffusion
Drug concentration
Higher concentration gradient → increased
permeation
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12. C. FORMULATION FACTORS
C. Formulation Factors
Type of vehicle/base (hydrophilic/lipophilic balance)
Use of permeation enhancers
Presence of occlusive backing (enhances hydration)
pH and viscosity of formulation
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13. 4.Permeation Enhancers (Penetration
Enhancers)
Definition:
Compounds that increase the permeabilityof the skin by altering the stratum corneum
structurewithout damaging it.
Mechanisms of Action
Disruption of lipid structure–e.g., fatty acids, surfactants.
Interaction with keratin–changing protein conformation.
Increasing drug partitioninginto skin layers.
Improving skin hydration(swelling of SC).
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14. Permeation Enhancer
Ideal Properties of a Permeation Enhancer
Non-toxic and non-irritating.
Reversible effect on barrier function.
Compatible with drug and excipients.
Chemically stable.
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15. EXAMPLES OF PERMEATION ENHANCERS
Category Examples Mechanism
Fatty acids Oleic acid, linoleic acid Disrupt lipid packing
Surfactants Sodium lauryl sulfate, Tween 80Solubilize lipids, alter SC
Solvents Ethanol, isopropyl myristateExtract lipids, improve partitioning
Terpenes Menthol, limonene Interact with lipids and keratin
Azone (laurocapram) Synthetic enhancer Increases lipid fluidity
Urea / Propylene glycol Humectants Increase hydration
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16. 5. BASIC COMPONENTS OF TDDS
A typical transdermal patchconsists of four to six layers, as shown below:
A. Basic Components
Polymeric Matrix / Drug Reservoir:
◦Holds drug and controls release rate.
◦Polymers: Eudragit®, PVP, HPMC, EVA, silicone rubber.
Rate-Controlling Membrane:
◦Regulates drug diffusion from reservoir to skin.
◦Materials: Polyethylene, EVA, ethyl cellulose.
Adhesive Layer:
◦Keeps patch attached to skin and may contain drug.
◦Pressure-sensitive adhesives (PSA): polyisobutylene, acrylates
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17. 4. Backing Layer:
•Protects patch from environment and provides support.
•Made of impermeable materials (polyester, aluminum foil).
5. Release Liner:
•Removed before application; protects adhesive surface.
•Made of silicon-coated film.
6. Permeation Enhancer Layer (optional):
•Improves flux across skin.
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18. 6. FORMULATION APPROACHES OF TDDS
Type Description Example
1. Drug-in-Adhesive System
Drug is directly incorporated into
adhesive layer; simplest design.
Nicoderm®
2. Reservoir System
Drug is in a liquid/gel reservoir,
separated by rate-controlling
membrane.
Transderm Scop®
3. Matrix Diffusion-Controlled
System
Drug dispersed in polymer matrix
that controls release.
Nitro-Dur®
4. Microreservoir System
Drug dissolved in aqueous
suspension within lipophilic matrix.
Nitrodisc®
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A. Types of Transdermal Systems

19. B. NEWER FORMULATION APPROACHES
Iontophoresis:
◦Uses mild electric current to drive charged drugs through the skin.
◦Example: Lidocaine iontophoresis patch.
Sonophoresis(Ultrasound):
◦Uses ultrasonic energy to enhance permeability.
Microneedle Arrays:
◦Create microchannelswithout pain; useful for macromolecules.
Electroporation:
◦High-voltage pulses cause transient pores in SC.
Nanocarrier-based TDDS:
◦Liposomes, ethosomes, niosomes, solid lipid nanoparticles enhance penetration.
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20. 7. EVALUATION OF TDDS
Parameter Method
Thickness and weight uniformity Micrometer, weighing balance
Drug content UV/ HPLC analysis
Moisture content/uptake Gravimetric methods
Folding endurance Manual folding
Adhesive properties Peel adhesion test
In-vitro drug release Franz diffusion cell
Skin irritation study On animal or human volunteers
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21. 8. IDEAL DRUG CANDIDATES FOR TDDS
Dose:≤ 10 mg/day
Molecular weight:< 500 Da
Log P:1–4
Melting point:< 200°C
Half-life:Short (< 10 h)
Non-irritant and stable in skin conditions
Examples:Nitroglycerin, Scopolamine, Clonidine, Estradiol, Nicotine, Fentanyl.
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22. APPLICATIONS OF TDDS
. Applications of TDDS
Cardiovascular diseases:Nitroglycerin, clonidine
Hormone replacement therapy:Estradiol, testosterone
Smoking cessation:Nicotine patch
Pain management:Fentanyl patch
Motion sickness:Scopolamine patch
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23. STRUCTURE OF A TRANSDERMAL PATCH
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24. Future Perspectives
10. Future Perspectives
Smart TDDS with biosensorsfor feedback-controlled release.
Nanocarrierintegrationfor peptide/protein delivery.
3D printed patcheswith personalized dosing.
Combination therapy patches(e.g., analgesic + anti-inflammatory).
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25. SUMMARY TABLE: KEY CONCEPTS
Concept Key Point
Main barrier Stratum corneum
Ideal MW < 500 Da
Ideal log P 1–4
Enhancers Oleic acid, menthol, ethanol
System types Matrix, reservoir, adhesive
Evaluation Thickness, drug content, diffusion study
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26. REFERENCE
Robinson, J.R., & Lee, V.H.L. (Eds.)
Controlled Drug Delivery: Fundamentals and Applications(2nd Edition)
Publisher: Marcel Dekker, New York.
Guy, R.H., & Hadgraft, J.
Transdermal Drug Delivery(Drugs and the Pharmaceutical Sciences Series, Vol. 35)
Publisher: Marcel Dekker Inc., New York.
Khar, R.K., Vyas, S.P. (Eds.)
Controlled Drug Delivery: Concepts and Advances
Publisher: VallabhPrakashan, New Delhi.
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27. THANK YOU
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