Targetted Drug Delivery

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History

The history of controlled release technology is dividedinto three time periods.

From 1950 to 1970 was the period of sustain drug

releaseFrom 1970 to 1990 was involved in the determination

of the needs of the control drug delivery

Post 1990 modern era of controlled releasetechnology

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Targeted drug delivery sometimes called as “smartdrug delivery”.

It is a method of delivering medication to a patient in

a manner that increases the concentration of

medication in some part of the body relative to

others.

It is highly selective.

It is very effective in treatment of cancer and tumor .

TARGETED DRUG DELIVERY SYSTEM

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Drug administration protocols may be simplified;

Drug quantity may be greatly reduced as well as the

cost of therapy;

Drug concentration in the required sites can be sharply

increased without negative effects on non-target

compartments.

ADVANTAGES OF DRUG TARGETING

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Oral Administration

•  Advantages

Easy

 Appropriate forpatient of any age.

No nursing isrequired.

• Disadvantages

Unconscious patientscannot take dose

Unsuitable in patients who are notcooperative

Unpredictableabsorption.

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Oral Administration 

• Traditional oraldelivery systems

 – Tablets

 – Capsules – Soft gelatin capsules

 – Elixirs

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Intravenous

•  Advantages

 – Rapid response – Total control of blood

concentration.

• Disadvantages – Suitable vein – Trained personnel – Possible toxicity due to

incorrect dosing

• Traditional deliverysystem/devices – Injection-bolus

 – IV bag– infusion

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Inhalers 

•  Advantages

 – Gases are rapidlyabsorbed

• Disadvantages

 – Solids and liquidscan be absorbed if

size is below 0.5um

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Release Profile

Drug delivery systems arose as a way to maintain blooddrug concentration levels between therapeutic limitsfor prolonged times

Their release profile is a consequence ofone or more

release mechanisms:(i) desorption of drug bound to the surface

(ii) diffusion through

(iii) diffusion through the capsule shell

(iv)  matrix erosion and

(v)  a combined erosion–diffusion process

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Types of drug release profiles

(A) Naked drug where the release profile is based onsimple diffusion and partition. (B) Zero-order releaseprofile, (C) Programmed release profile.

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Factors that affect the drug release

Drug-Material interaction

Morphologiesarchitectures of the encapsulated forms

biodegradability mechanisms

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Carrier materials used for DDSLipids

polymers

Metalsmagnetic substances

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Lipids

This group contains phospholipids and cholesterol,the main liposomal components.

They are amphiphilic molecules, a feature that allow

them to form the bilayered membranes present inliposomes.

cholesterol is used for fluidity regulation ofphospholipidic membranes.

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Many types of polymers are used in nDDS, bothbiodegradable and non-biodegradable

PLA is a biodegradable thermoplastic linear aliphaticpolyester that has been used for the manufacture of implants,stents, and medical devices.

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LEVELS OF DRUG TARGETING

Passive targeting

 Active targeting

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Passive targeting

Passive targeting is the employment of somepathophysiological features of targeted tissue that allowaccumulation of nDDS and drug release inside it, without

using any ligands or external stimuliIt involves extensive angiogenesis, high vascular density,

defective vascular architecture, impaired lymphaticclearance from the interstitial space of tumor tissue and

increased permeability induced by various vascularmediators

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Active targeting:

The facilitation of the binding of the drug carrier totarget cells by the use of ligands to increase receptormediated localization of the drug and target specificdelivery of drug is referred to as active targeting.

 Active targeting is not a targeting method and hence itcannot happen without the occurrence of passivetargeting first.

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1. Extravasation through endothelia followed by nDDS

uptake2. nDDS can also be decomposed during circulation andthe encapsulated drug gets degraded beforeinternalization

3. Non specific adhesion of cationic carriers to negativeendothelia of blood vessels leading to occlusion of the vessel

4. Platelet aggregation, an undesired event, whichincrease the risk of embolism

5. Opsonization with opsonin protein

6. activation of complement system leading todegradation and

7. phagocytosis

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Recent approaches

1. Quantum dots2. Transdermal Approach

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Quantum dot beads

Healthy cells

Cancer cells

Quantum dot beads

Healthy cells

Cancer cells

Quantum Dots Can Find Cancer Signatures

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Nanotechnology TreatmentTraditional Treatment

ToxinsDrugs

Cancercells

Noncancerous cells

Deadcancercells

Dead noncancerous cells

Cancercells

Noncancerous cells

Dead

cancer

cells

Intact noncancerous cells

Toxins

Cancer Treatment

Nanodevices

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Transdermal Approacho  It is topically administered medicaments in the

form of patches that deliver drugs for systemiceffects at a predetermined and controlled rate.

o  A transdermal drug delivery device, provides analternative route for administering medication.

o These devices allow for pharmaceuticals to bedelivered across the skin barrier.

 A 21mg dose 

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Hazards of nanoparticle.

 nanomaterials may contribute to the formation of free radicalsdamage of brain cells

undesirable penetration through the epidermis or other

physiological barriers into areas of the body that are more

susceptible to toxic effects quantum dots show cytotoxicity by induction of reactive oxygen

species, resulting in damage to the nucleus, mitochondria and

plasma membranes

it was reported that most cationic Nano-Particles can cause

hemolysis and blood clotting

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Thank you