METHODS OF PROLONGING DRUG ACTION

Dr.RAGHU PRASADA M SMBBS,MDASSISTANT PROFESSOR DEPT. OF PHARMACOLOGYSSIMS & RC.

Advantages

Decrease the frequency of administration Improve patient compliance Decrease fluctuation in plasma concentration To maintain drug effects for longer time

Prolong absorption –from site of administration

Oral –sustained release tablets, controlled release tablets

Parenteral- sc and im injection of drugs in insoluble form-benzathine pencillin, lente insulin

Transdermal drug delivery system By increasing plasma protein binding- slow release-

sulfadoxine

Prodrugs

Inactive drug Levodopadopamine Procaine pencillin-G

Transdermal DDSActive ingredient is delivered across the skin for systemic distribution.

Example: transdermal scopolamine, transdermal nitroglycerine,

By retarding rate of metabolism Chemical modification Ethinyl group to estradiol –OCPs Allopurinol—6-Mercaptopurine Ritonavir –boosts level of Indinavir

BY RETARDING RENAL EXCRETIONProbenacid prolongs duration of action of pencillin

Targeted drug delivery systems Colloidal drug carriers

1. micro and nano particles

2. macro molecular complex

3. Liposomes and niosomes

Ligand mediated targeting

1. Vascular compartment

2. Cellular compartment3. Intracellular 4. Monoclonal

antibodies5. Resealed erythrocytes

Liposomes as drug carriers

Liposomes are spherical, self closed structures composed of curved lipid bilayers which entrap part of the solvent, in which they freely float, into their interior. They may consist of one or several concentric membranes; their size ranges from 20 nm to several dozens µm, while thickness of the membrane is around 4 nm.

Special drug delivery systems

Ocuserts –thin epithelial microunits Ex. Pilocarpine occusert-gloucoma

Progestaserts- intrauterine contraceptive device

Drug encapsulated in liposomes for intravenous infusion –Amphotericin B

THANK YOU

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