TDDS

TRANSDERMAL DRUG DELIVERY

SYSTEM

PRESENTED TO PRESENTED BY MRS. MARY KOSHY REETU ASSOCIATE PROFESSOR M.PHARM (PHARMACEUTICS)

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The Skin

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Transdermal drug delivery system

Transdermal drug delivery system is defined as self

containing,discrete dosage forms which when applied to

the intact skin,deliver the drugs through the skin at a

controlled rate to the systemic circulation.

Transdermal delivery represents an attractive alternative

to oral delivery of drugs and is poised to provide an

alternative to hypodermic injection too.

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Advantages

Avoid gastrointestinal drug absorption difficulties caused by gasrtointestinal pH, enzymatic activity, drug interaction.

Substitute for oral administration of medication. Avoid first pass effect. Noninvasive in nature. Extended therapy with a single application. Improving compliance. May be terminated rapidly. Easily and rapidly identified in emergencies.

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Disadvantages Many drugs especially drugs with hydrophilic structures

permeate the skin too slowly may not achieve therapeutic level.

The drug, the adhesive or other excipients in the patch formulation can cause erythema, itching and local edema.

The barrier function of the skin changes from one site to another on the same person, from person to person and also with age.

Drug that require high blood levels cannot be administered

Adhesive may not adhere well to all types of skin

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Consideration of TDS development

Bioactivity of drug

Skin characteristics

Formulation

Adhesion

System design

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Properties that influence Transdermal delivery of the drug

Release of the medicament from the vehicle. Penetration through the skin barrier.

› Skin structure and its properties› The penetrating molecule and its physical-chemical

relationship to skin and the delivery platform› The platform or delivery system carrying the

penetrant› The combination of skin, penetrant, and delivery

system Activation of pharmacological response.

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Factors influence transdermal deliveryo Biological factors –

o Skin condition

o Skin age

o Blood flow

o Regional skin sites

o Skin metabolism

o Species differences

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Physicochemical factors –

Skin hydration

Temperature and pH

Diffusion coefficient

Drug concentration

Partition coefficient

Molecular shape and size

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Process of transdermal permeation

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Pathway of drug penetration

1.Through stratum corneum

2.Transfollicular

3.Through sweat gland

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Basic components of TDDS

The drug

Polymer matrix

Permeation enhancers

Adhesive

Backing layer.

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Drug

The drug is in direct contact with release liner. Ex: Nicotine, Methotrexate, and Oestrogen.

Some of the desirable properties of a drug for transdermal delivery:

Should possess an adequate solubility in oil and water. Should have a molecular weight less than approximately 1000

daltons. Require a balanced partition coefficient to penetrate the stratum

corneum. Should have low melting point.

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Polymer matrix

These polymers control the release of the drug from the drug reservoir.

Natural polymers: shellac, gelatin, waxes, gums, starch etc.

Synthetic polymers: polyvinyl alcohol, polyamide, polyethylene, polypropylene, Polyurea, polymethyl methacrylate.

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Permeation enhancers

Substances exist which temporarily diminish the

impermeability of the skin are known as accelarants or sorption promoters or penetration enhancers.

These include water, pyrolidones, fatty acids and alcohols, azone and its derivatives, alcohols and glycols, essential oils, terpenes and derivatives, sulfoxides like dimethyl sulfoximide and their derivatives, urea and surfactants

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Adhesive

Serves to adhere the patch to the skin for systemic drug delivery of the drug

Ex: Silicones, Polyisobutylene

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Backing layer

Backing layer protects patch from outer environment.

Ex: Cellulose derivatives, Polypropylene silicon rubber

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Transdermal drug delivery devices

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Types of TDDS

There are main four types of TDDS

Membrane moderated system

Adhesive diffusion controlled system

Matrix dispersion system

Micro reservoir system.

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Matrix dispersion type TDDS

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Transdermal controlled release products

Drug Trade Name Type of Device

Indication

Scopolamine Transderm scop Reservoir Motion sickness

Nitroglycerine Transderm nitro Reservoir Angina

Nitro dur Monolithic

Nitro disc Monolithic

Estradiol Estraderm Reservoir Hormone treatment

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References 1. Prausnitz MR, Mitragotri S, Langer R. Current status

and future potential of transdermal drug delivery.t Rev Drug Discov. 2004;3:115–124.

2. Bronaugh RL, Maibach HI, editors. Edn. 4th. New York: Marcel Dekker; 2005. Percutaneous Absorption.

3. Jain N.K. ,Pharmaceutical Product Development, First edition,CBS publishers

4. Aulton.M.E, Pharmaceutics; The science of dosage form design, second edition, Marcel Dekker;2002.502-505.

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5. Allen L.V.; Ansel.H.C ;Popovich.N.G ,Pharmaceutical dosage forms and drug delivery systems, Ninth edition, Lippincott Williams and Wilkins publication,2011,295.

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