IMPLANTABLE THERAPEUTIC SYSTEMS-I

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A warm wishes to all


And I am here presenting my first blog of this month on the introduction of the implantable therapeutic system.

Introduction: (1)

As the name suggests, here drug in a suitable dosage form is implanted in the subcutaneous tissue which provides the release of the drug for a prolonged period of time. This technique was initially pioneered by Lafarge in 1861.

Again this technique was rediscovered by Deanesly and Parkes in 1936. They compressed crystalline hormones to produce solid steroid pellets to
get steady, continuous release of hormones like that naturally happens from an active gland.

The first biomedical approach to get a continuous and prolonged drug administration was the subcutaneous implantation of drug pellets.

Subcutaneous tissue present underneath the skin is considered as a suitable route for implantable administration because it is very poor in blood circulation, nerves supply and rich in fat which facilitates slow absorption of the drug, easy assessment of implants and low reactivity to the inserted implant.

Advantages: (2)

1.Plasma drug level can be maintained continuously below.

2.The side effects can be minimized.

3.Improved patient compliance.

4.More economic as less amount of the drug is used.

5.Drugs having shorter biological half life can be administered.

Disadvantages (2)

1.Possible toxicity

2.Requirement of surgery for the implantation

3.Difficulty in immediate shutting off of release when required.

Applications:

(1) It is used in the HRT(Hormone
replacement therapy).

2. By using the intracranial base implants we can attain high drug levels in the blood in case

of the dexamethasone.

3.By the use of the infusion pumps we can control the blood glucose levels in case of Diabetes for a long period of time.

4.This is also used as subdermal contraceptive implants consisting of the drugs like

progestin.

5.Mitomycin when administered as implant by the intraperitoneal route provides more

tumoricidal effect.

6.It is used in the chemical castration during the treatment of prostate cancer.

7.Bone implants can be used in the treatment of bone infection.

8.In the treatment of Cytomegalovirus infection in the eye sclera implants containing the drug gancyclovir are being used.

Implants may be applied in the form of semisolids or thick liquids or drug pellets or rods or gel forming liquids.

Fabrication and release of the drug (1)

1.in many cases these consists of the drug pellet(solid) which is mixed with the

excipients(including polymer substances). The polymer substances may be either biodegradable or non-degradable.

2.Thick liquids or semisolids are administered into the area where the action is required with the help of the needle.

3.By forming the gel insitu.

Ideal Characteristics: (2)

1.It should increase the patient compliance.

2.It should have the ability to give sustained release during the period of treatment.

3.It should have less adverse effects.

4.It should be implantable readily without any major surgery.

5.It should be less costlier.

6.It should be easy to prepare.

References:

1.novel drug delivery by yie w.chien, 2nd edition, informa publishers, page no441 to 518

2.advances in controlled and novel drug delivery by n.k.jain, cbs publishers, 2008 reprint, page no 204 to 222

"This blog does not contain plagiarized material"

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