transdermal drug delivery system

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Pharmaceutical Technology III ASSIGNMENT Submitted to Dr. Mohammad Shahriare Assistant Professor North South University Submitted by Shahnaz Jalil 1210675046 Sumaiya Sattar Chowdhury S.M. Nazmul Hauque 1210084046 Rafsan Ahmed 1030590546 Sidratul Jannat chowdhury MD.Hamza Naquib 1210098046

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Page 1: transdermal drug delivery system

Pharmaceutical Technology IIIASSIGNMENT

Submitted toDr. Mohammad ShahriareAssistant Professor North South University

Submitted byShahnaz Jalil 1210675046Sumaiya Sattar Chowdhury S.M. Nazmul Hauque 1210084046Rafsan Ahmed 1030590546Sidratul Jannat chowdhury MD.Hamza Naquib 1210098046

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Transdermal drug delivery system

Introduction:

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.

TDDS is also called transdermal therapeutic system or transdermal patches.

Transdermal drug delivery has made an important contribution to medical practice.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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Transdermal drug delivery system includesall topically administered drug formulations intendedto deliver the active ingredients into the circulation.They provide controlled continuous delivery of drugsthrough the skin to the systemic circulation. The drugis mainly delivered through the skin with the aid oftransdermal patch. A Transdermal patch is amedicament adhesive patch that is placed on the skinto deliver a specific dose of medication through theskin and into the bloodstream. A drug is applied in arelatively high dose to the inside of a patch, which isworn on the skin for an extended period of time.Through a diffusion process, the drug enters thebloodstream directly through the skin. Since there ishigh concentration in the patch and low concentrationin the blood, the drug will keep diffusing into theblood for a long period of time, maintaining theconstant concentration of drug in the blood flow

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Rational approach for transdermal drug delivery via skin

1. We can manipulate the barrier function of the skin; for example- topical antibiotics and antibacterials help a damaged barrier to ward off infection, sunscreen agents and the horny layer protect the viable tissues from ultraviolet radiation and emollient preparations restore pliability to a desiccated horny layer.

2. Or we can deliver drugs directly to the viable skin tissues without using oral, systematic or other routes of therapy.

3. The third approach is using skin delivery for systematic treatment.

For example- transdermal therapeutic systems provide systemic therapy for conditions such as motion sickness angina and pain.

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Advantages of Transdermal drug delivery over the conventional dosage forms:

1. The Transdermal drug delivery system(TDDS) can be defined as a delivery device,which upon application on a suitable skinsurface will be able to deliver the drug into thesystemic circulation at sufficient concentrationto ensure therapeutic efficacy, an additionallimitation to oral drug delivery, can be avoidedwith transdermal administration.

2. Steady permeation of drug across the skin,allowing consistent serum drug level, often agoal of therapy.

3. Similar to intravenous infusion, it alsoachieves consistent plasma levels, butnoninvasive in nature.

4. In addition, if toxicity develops from a drugadministered transdermally, the effects couldbe moderated by removing the patch.

5. Transdermal drug delivery can be used as analternative delivery system for patients whocannot tolerate oral dosage forms.

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6. It is of great advantage in patients who arenauseated or unconscious.

7. Drugs that cause gastrointestinal upsets can begood candidates for transdermal deliverybecause this method avoids direct effects onstomach and intestine.

8. Another advantage is convenience, especiallynotable in patches that require only onceweekly application. Such a simple dosingregimen can aid in patient adherence to drugtherapy.

9. Peaks and troughs in plasma level can beavoided, which reduce the risk of side effects.Thus, drugs that require consistent plasmalevels are very good candidates fortransdermal drug delivery.

10. Allows continued drug administrationpermitting the use of a drug with shortbiological half-life.

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Common disadvantages of TDDS:

1. Many drugs especially drugs with hydrophilicstructures permeate the skin too slowly may notachieve therapeutic level.2. The drug, the adhesive or other excipients in thepatch formulation can cause erythema, itching,and local edema.3. The barrier function of the skin changes fromone site to another on the same person, fromperson to person and also with age.

Properties that influence Transdermal delivery of the drug:

a. Release of the medicament from the vehicle.b. Penetration through the skin barrier.c. Activation of the pharmacological response.

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Stratum Corneum (topmost 15 μm layer) is the main barrier

Pathway of drug penetration:

1.Through stratum corneum 2.Transfollicular 3.Through sweat gland

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Mechanism of Drug penetration:

Hydrophilic drugs permeates by Intercellular pathway and Lipophilic drugs permeates by Intracellular (Transcellular) mechanism

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Strategies to enhance drug permeability by transdermal system:

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FACTORS THAT INFLUENCE TRANSDERMALDRUG DELIVERY:

Biological factors include:1. Skin condition2. Skin age3. Blood flow4. Regional skin sites5. Skin metabolism6. Species differencesPhysiological factors include:1. Skin hydration2. Temperature and pH3. Diffusion coefficient4. Drug concentration5. Partition coefficient6. Molecular size and shapeBASIC COMPONENTS OF TDDS:1. The drug2. Polymer matrix3. Permeation enhancers4. Adhesive5. Backing layer.

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Basic component of TDDS:1. DRUGThe drug is in direct contact with release liner.Ex: Nicotine, Methotrexate, and Oestrogen.

Some of the desirable properties of a drug fortransdermal delivery:

1. The drug molecule should possess an adequatesolubility in oil and water.2. The drug should have a molecular weight less thanapproximately 1000 daltons.3. The drug should have low melting point.4. The drug molecule would require a balanced partition co efficient to penetrate the stratum corneum.

2. POLYMER MATRIXThese polymers control the release of the drug fromthe drug reservoir.Natural polymers: shellac, gelatin, waxes, gums, starchetc.,Synthetic polymers: polyvinyl alcohol, polyamide,polyethylene, polypropylene, Polyurea, polymethyl methacrylate.

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3. PERMEATION ENHANCERS:Substances exist which temporarily diminish theimpermeability of the skin are known asaccelarants or sorption promoters or penetrationenhancers. These include water, pyrolidones, fattyacids and alcohols, azone and its derivatives, alcoholsand glycols, essential oils, terpenes and derivatives,sulfoxides like dimethyl sulfoximide and theirderivatives, urea and surfactantsSurfactants are proposed to enhance polar pathwaytransport especially of hydrophilic drugs. The abilityof a surfactant to alter penetration is a function of thepolar head group and the hydrocarbon chain length.Anionic surfactants: sodium lauryl sulphate,Decodecylmethyl sulphoxide etc.Lipid action The enhancer interacts with theorganized intracellular lipid structure of the stratumcorneum so as to disrupt it and make it morepermeable to drug molecules. Very many enhancersoperate in this way. Some solvents act by extractingthe lipid Components and thus make the horny layermore permeable.

Protein modification Ionic surface active moleculesin particular tend to interact well with the keratin in thecorneocytes, to open up the dense keratin structure andmake it more permeable.

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Partitioning promotion: Many solvents can enter the stratum corneum , changes its solventProperties and thus increase the partitioning of a socond molecule into the horny layer.the molecue may be drug, a coenhancer or a co solvent.For example ethanol has been used to increase thepenetration of the drug molecules nitroglycerin and estradiol.

4. ADHESIVEServes to adhere the patch to the skin for systemic drug delivery of the drug:Ex: Silicones, Polyisobutylene.5. BACKING LAYERBacking layer protects patch from outer environment.Ex: Cellulose derivatives, Polypropylene siliconrubber

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FACTORS AFFECTING TRANSDERMAL BIOAVAILABILITY

Two major factors affect the bioavailability of the drugthrough transdermal routes:(1)Physiological factors (2) Formulation factorsPhysiological factors include:i. Stratum corneum layer of the skinii. Anatomic site of application on the bodyiii. Skin condition and diseaseiv. Skin metabolismv. Skin irritation and sensitizationFormulation factors include:(i) Penetration enhancers used(ii) Vehicles and membrane used(iii) Physical chemistry of transport(iv) Method of application(v) Device used

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Transdermal drug delivery technologies are becoming one

of the fastest growing sectors within the pharmaceutical

industry.

Advances in drug delivery systems have increasingly

brought about rate controlled delivery with fewer side

effects as well as increased efficacy and constant drug

delivery.

The market value for transdermal delivery was $12.7

billion in 2005, and is expected to increase to $21.5 billion

in the year 2010 and $31.5 billion in the year 2015 –

suggesting a significant growth potential over the next 10

years.

Reference:

Conclusion:

http://sphinxsai.com/Vol.3No.4/pharm/pdf/PT=39(2140-2148)OD11.pdf

Controlled drug delivery –concepts and advances – by S.P.Vyas R.K.Khar.

Auton’s Pharmaceutics- the designand manufacture of medicines.