20-10-2012, 04:37 PM
Ocular Drug Delivery System
OCULAR DDS Vnips.pptx (Size: 1.26 MB / Downloads: 29)
Factors Affecting Intraocular Bioavailability:
Spillage of drug by over flow.
Dilution with tears.
Inflow & Outflow of Lacrimal fluids.
Naso-lacrimal drainage.
Conjunctival absorption.
Enzymatic metabolism.
Interaction of drug with proteins of Lacrimal fluid.
Approaches to Improve ocular delivery of drugs
Prolonged contact time of drug with corneal surface
Approaches to enhance corneal permeability either by mild structural alteration of corneal epithelium or by modification of chemical structure of drug molecules
Recent formulation trends
Polymeric solutions e.g: MC, PVA, HPC& PVP
Phase transition systems : Gelrite (gellan gum)
e.g: Lutrol FC-127& Polaxomer 407 viscosity increases when its temperature raised to 37oC
e.g: CAP pH sensitive
Mucoadhesive/Bioadhesive dosage forms
Hydrophilic colloids with hydrophilic functional groups
e.g: Polycarbophil(acrylic acid based polymer)
Collagen shields, Collasomes (Collagen protein from bones, ligaments, tendons, skin)
e.g: antibiotic impregnated soft contact lenses
Polymeric colloidal dispersions (o/w type emulsion)
Ocular penetration enhancers: surfactants, bile salts, chelators, organic compounds, actin filament inhibitors
Ocular Iontophoresis: Direct current derives ions into cells/tissues
Implantable silicone rubber devices
Drug delivery device for hydrophobic drugs
e.g.:-BCNU(1,3-bis(2-chloro ethyl)-1-nitroso urea)---- an intraocular malignancy agent
The device consists of two sheets of silicone rubber glued together only at the edges with silicone adhesive
A tube of the same material extends from device
The device released BCNU at a constant rate about 200-400mcg/hr
Advantages of vesicular systems
No difficulty of insertion as in the case of ocular inserts
No tissue irritation and damage as caused by penetration enhancers
Provide patient compliance as there is no difficulty of insertion as observed in the case of inserts
The vesicular carriers are biocompatable and have minimum side effects
Degradation products formed after the release of drugs are biocompatible
They prevent the metabolism of drugs from the enzymes present at tear/corneal epithelium interface
Provide a prolong and sustained release of drug
OCULAR DDS Vnips.pptx (Size: 1.26 MB / Downloads: 29)
Factors Affecting Intraocular Bioavailability:
Spillage of drug by over flow.
Dilution with tears.
Inflow & Outflow of Lacrimal fluids.
Naso-lacrimal drainage.
Conjunctival absorption.
Enzymatic metabolism.
Interaction of drug with proteins of Lacrimal fluid.
Approaches to Improve ocular delivery of drugs
Prolonged contact time of drug with corneal surface
Approaches to enhance corneal permeability either by mild structural alteration of corneal epithelium or by modification of chemical structure of drug molecules
Recent formulation trends
Polymeric solutions e.g: MC, PVA, HPC& PVP
Phase transition systems : Gelrite (gellan gum)
e.g: Lutrol FC-127& Polaxomer 407 viscosity increases when its temperature raised to 37oC
e.g: CAP pH sensitive
Mucoadhesive/Bioadhesive dosage forms
Hydrophilic colloids with hydrophilic functional groups
e.g: Polycarbophil(acrylic acid based polymer)
Collagen shields, Collasomes (Collagen protein from bones, ligaments, tendons, skin)
e.g: antibiotic impregnated soft contact lenses
Polymeric colloidal dispersions (o/w type emulsion)
Ocular penetration enhancers: surfactants, bile salts, chelators, organic compounds, actin filament inhibitors
Ocular Iontophoresis: Direct current derives ions into cells/tissues
Implantable silicone rubber devices
Drug delivery device for hydrophobic drugs
e.g.:-BCNU(1,3-bis(2-chloro ethyl)-1-nitroso urea)---- an intraocular malignancy agent
The device consists of two sheets of silicone rubber glued together only at the edges with silicone adhesive
A tube of the same material extends from device
The device released BCNU at a constant rate about 200-400mcg/hr
Advantages of vesicular systems
No difficulty of insertion as in the case of ocular inserts
No tissue irritation and damage as caused by penetration enhancers
Provide patient compliance as there is no difficulty of insertion as observed in the case of inserts
The vesicular carriers are biocompatable and have minimum side effects
Degradation products formed after the release of drugs are biocompatible
They prevent the metabolism of drugs from the enzymes present at tear/corneal epithelium interface
Provide a prolong and sustained release of drug