ocular drug delivery


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ocular drug delivery

  1. 1. A Seminar on Ocular Drug Delivery System Presented by : V.Srujana M.Pharm Iyr(IIsem) Dept. Of P’ceutics KLR College.
  2. 2. CONTENTS <ul><li>Introduction </li></ul><ul><li>Human eye anatomy </li></ul><ul><li>Mechanism of ocular absorption </li></ul><ul><li>Factors affecting Intraocular bioavailability </li></ul><ul><li>Pharmacokinetics of ocular drug administration </li></ul><ul><li>Ophthalmic preparations </li></ul><ul><li>Classification of Ophthalmic dosage forms </li></ul><ul><li>Ocular control release system </li></ul><ul><li>Advances in ocular drug delivery </li></ul><ul><li>Conclusion and future outlook </li></ul><ul><li>Reference </li></ul>
  3. 3. INTRODUCTION <ul><li>Ocular administration of drug is primarily associated with the need to treat ophthalmic diseases. </li></ul><ul><li>Major classes of drugs used are </li></ul><ul><li>Miotics - cholinergic agents (ACh) </li></ul><ul><li>Mydriatics – anticholinergics (atropine) </li></ul><ul><li>anti-inflamatories </li></ul><ul><li>Anti-infectives </li></ul><ul><li>Surgical adjuvents </li></ul><ul><li>Diagnostics </li></ul><ul><li>These drugs are meant for local therapy and not for systemic action. </li></ul>
  4. 4. Human EYE Anatomy
  5. 5. <ul><li>Human eye </li></ul><ul><ul><li>Diameter of 23 mm </li></ul></ul><ul><ul><li>Structure comprises of three layers </li></ul></ul><ul><ul><li>Outermost coat : The clear, transparent cornea and the white, opaque sclera </li></ul></ul><ul><ul><li>Middle layer : The iris anteriorly, the choroid posteriorly, and the ciliary body at the intermediate part </li></ul></ul><ul><ul><li>Inner layer : Retina (extension of CNS) </li></ul></ul><ul><li>Cornea </li></ul><ul><ul><li>Epithelium-stroma-endothelium </li></ul></ul><ul><ul><li>(fat-water-fat structure) </li></ul></ul><ul><ul><li>Penetration of the drug depends on Oil-water partition coefficient </li></ul></ul><ul><li>Corneal cross section </li></ul>
  6. 7. <ul><li>Fluid systems in eye- </li></ul><ul><li>Aqueous humor: </li></ul><ul><li>Secreted from blood through epithelium of the ciliary body. </li></ul><ul><li>Secreted in posterior chamber and transported to anterior chamber. </li></ul><ul><li>Vitreous humor: </li></ul><ul><li>Secreted from blood through epithelium of the ciliary body. </li></ul><ul><li>Diffuse through the vitreous body. </li></ul><ul><li>Lacrimal glands: </li></ul><ul><li>Secrete tears & wash foreign bodies. </li></ul><ul><li>Moistens the cornea from drying out. </li></ul>
  7. 9. General Pathway For Ocular Absorption
  8. 10. <ul><li>Factors Affecting Intraocular Bioavailability: </li></ul><ul><li>Includes- </li></ul><ul><li>pre corneal </li></ul><ul><li>corneal </li></ul><ul><li>interior of the eye </li></ul><ul><li>1. Inflow & Outflow of Lacrimal fluids. </li></ul><ul><li>2. Efficient naso-lacrimal drainage. </li></ul><ul><li>3. Interaction of drug with proteins of Lacrimal fluid. </li></ul><ul><li>4. Dilution with tears. </li></ul><ul><li>5. Corneal barriers </li></ul><ul><li>6. Physico-chemical properties of drugs </li></ul><ul><li>7. Active ion transport at cornea, </li></ul>
  9. 11. Pharmacokinetics of ocular drug administration <ul><li>Tear fluid </li></ul><ul><li>Precorneal epithelial corneal stroma </li></ul><ul><li>Drug pool surface epithelium epithelium </li></ul><ul><li>aqueous </li></ul><ul><li>Nasolacrymal conjunctiva metabolism humor </li></ul><ul><li>Drainage system </li></ul><ul><li>Elimination </li></ul>
  10. 12. <ul><li>Ophthalmic preparation: </li></ul><ul><li>Ophthalmic preparations are sterile products that are intended to be applied topically to cornea or instilled in the space between the eyeball and lower eyelid. </li></ul><ul><li>Conventional ocular formulations for ocular drug delivery: </li></ul><ul><li>Solutions </li></ul><ul><li>Suspensions </li></ul><ul><li>Ointments </li></ul><ul><li>Gels </li></ul><ul><li>Emulsions </li></ul>
  11. 13. <ul><li>Solution </li></ul><ul><li>Dilute with tear and wash away through lacrimal apparatus. </li></ul><ul><li>Usually do not interfere with vision of patient. </li></ul><ul><li>To be Administered at frequent intervals. </li></ul><ul><li>Suspension </li></ul><ul><li>Longer contact time. </li></ul><ul><li>Irritation potential due to the particle size of the drug . </li></ul><ul><li>Ointment </li></ul><ul><li>Longer contact time and greater storage stability. </li></ul><ul><li>Producing film over the eye and blurring vision. </li></ul><ul><li>Interfere with the attachment of new corneal epithelial cells to their normal base. </li></ul>
  12. 14. Classification Of Ophthalmic Dosage Forms:
  14. 17. Ocular Control Release System: Ophthalmic Inserts Definition:- Solid or Semisolid in nature. - Placed in lower Fornix - Composed of Polymeric vehicle containing drug. Role Of Polymer In ODDS . Solution Viscosity : Solution Drainage. Polymer Mucoadhesive Vehicle: Retained in the eye due to non-covalent bonding with conjuctival mucine. Mucine is capable of picking of 40-80 times of weight of water.
  15. 18. Drug Administration: <ul><li>“ Pulse entry ” of the drug. </li></ul><ul><li>Rapid , 1 st order decline of drug concentration. </li></ul>
  16. 19. Requisites For Control Release Ocular delivery systems
  17. 21. Approaches to improve topical delivery of drugs <ul><li>To prolong the contact time of drug with corneal surface </li></ul><ul><li>To enhance corneal permeability either by mild or transient structural alteration of corneal epithelium or modification of chemical structure of drug molecules. </li></ul><ul><li>Recent trends: </li></ul><ul><li>Polymeric solutions </li></ul><ul><li>Phase transition systems </li></ul><ul><li>Mucoadhesive/ bioadhesive dosage forms </li></ul><ul><li>Collagen shields </li></ul><ul><li>Pseudolatices </li></ul><ul><li>Ocular penetration enhancers </li></ul><ul><li>Ocular Iontophoresis </li></ul>
  18. 22. Ocular drug delivery devices: <ul><li>Matrix type DDS – Hydrophilic soft contact lens </li></ul><ul><li>SODI </li></ul><ul><li>Capsule type DDS – ocusert </li></ul><ul><li>Implantable DD pumps – osmotic mini pumps </li></ul><ul><li>Other devices – lacrisert </li></ul><ul><li>minidisk ocular therapeutic system </li></ul><ul><li>The new ophthalmic delivery system </li></ul><ul><li>Particulate systems – microspheres & Nanoparticles </li></ul><ul><li>Vesicular system – liposomes </li></ul><ul><li>niosomes </li></ul>
  19. 23. Types Of Ocular Control Release System
  20. 24. A) Non-Erodible : <ul><li>1.Ocusert: </li></ul><ul><li>Developed by Alza Corporation, </li></ul><ul><li>Oval flexible ocular insert, </li></ul><ul><li>Release Rate: 20-40mg/hr </li></ul><ul><li> for 7day </li></ul><ul><li>Consist of- </li></ul><ul><li>Annular ring : Impregnated with Ti0 2 : For Visibility </li></ul>
  21. 25. 2. Contact Lens : <ul><li>Presoaked Hydrophilic lens. </li></ul><ul><li>Drug Release : within 1 st 30 Min. </li></ul><ul><li>Alternate approach : incorporate drug either as sol n or suspension of solid monomer mixture. </li></ul><ul><li>Release rate is up to : 180 hr. </li></ul><ul><li>3. Diffusional Inserts : </li></ul><ul><li>Central reservoir of drug enclosed in Semi permeable or micro porous membrane for diffusion of drug. </li></ul><ul><li>Diffusion is controlled by Lacrimal Fluid penetrating through it. </li></ul><ul><li>It prevents continues decrease in release rate due to barrier. </li></ul><ul><li>Release follows : Zero Order Kinetics . </li></ul>
  22. 26. B) Erodible Inserts <ul><li>1.Lacrisert: </li></ul><ul><li>Sterile, Rod Shaped device. </li></ul><ul><li>Composition: HPC without preservative. </li></ul><ul><li>Weight:5mg, </li></ul><ul><li>Dimension:Diameter:12.5mm, Length:3.5mm </li></ul><ul><li>Use:-Dry eye treatment, Keratitis Sicca. </li></ul><ul><li>2.SODI: Soluble Ocular Drug Insert. </li></ul><ul><li>Small water soluble developed for Cosmonauts who could not use their eye drop in liquid condition. </li></ul><ul><li>Composition : Acryl amide, Vinyl Pyrolidone, Ethylacrylate. </li></ul><ul><li>Weight 15-16 mg. </li></ul><ul><li>In 10-15 sec Softens; </li></ul><ul><li>In 10-15 min. turns in Viscous Liquids; </li></ul><ul><li>After 30-60min. Becomes Polymeric Solution. </li></ul>
  23. 27. Advantages of SODI : <ul><li>Single SODI application :replaces 4-12 eye drops Instillation, </li></ul><ul><li> or 3-6 application of Ointments. </li></ul><ul><li>Once a day treatment of Glaucoma & Trachoma . </li></ul><ul><li>3)Minidisc: </li></ul><ul><li>It is made up of counter disc with Convex front & Concave back surface in contact with eye ball. </li></ul><ul><li>4-5mm in diameter. </li></ul><ul><li>Composition : Silicon based pre polymer. </li></ul><ul><li>Hydrophilic or Hydrophobic. </li></ul><ul><li>Drug release from 170 hr. </li></ul>
  24. 28. C) Nanoparticle:
  25. 29. D) Liposome
  26. 30. The New Ophthalmic Delivery System (NODS) <ul><li>Delivers precise amount of drug to the eye. </li></ul><ul><li>Device consists of medicated film attached to paper cover and handled by a short and thin membrane. </li></ul><ul><li>All components are packed individually and sterilized by gamma irradiation. </li></ul><ul><li>Membrane dissolves in lacrimal fluid and delivers the drug. </li></ul><ul><li>Study result: NODS produced 8-fold increase in bioavailability for pilocarpine with respect to standard eye drop formulation. </li></ul>
  27. 31. RETROMETABOLIC DRUG DESIGN CONCEPT (RMDD) <ul><li>Metabolism: Molecules introduced into body are modified by enzymes. </li></ul><ul><li>Basic principle: Drug metabolism consideration. </li></ul><ul><li>Metabolism results in structural changes to molecule which inturn causes changes in physioco-chemical properties of parent molecule </li></ul><ul><li>New Drug design: SAR (structural activity relationship), and SMR (structural metabolic relationship) are used in combination. This approach of drug design is called RMDD. </li></ul>
  28. 32. Advances in ocular drug delivery <ul><li>1. Ophthalmic gel for pilocarpine </li></ul><ul><li>Poloxamer 407 (low viscosity, optical clarity, mucomimetic property) </li></ul><ul><li>2. Ophthalmic prodrug </li></ul><ul><li>Dipivalyl epinephrine (Dipivefrin) </li></ul><ul><li>Lipophilic  increase in corneal absorption </li></ul><ul><li>Esterase within cornea and aqueous humor </li></ul><ul><li>3. Continuous delivery system based upon the osmotic property </li></ul><ul><li>Thin flat layer, contoured three-dimensional unit </li></ul><ul><li>Conform to the space of the upper cul-de-sac </li></ul><ul><li>Delivery of diethyl carbamazine in ocular onchocerciasis </li></ul>
  29. 33. 4. Gel delivery system <ul><li>Biodegradable polyisobutyl-cyano acrylate (PIBCA) colloidal particulate system of pilocarpine to incorporate it into a Pluronic F127 (PF 127)-based gel delivery system. </li></ul><ul><li>5. Mucoadhesive Polymer. </li></ul><ul><li>Mucoadhesive polymer, the tamarind seed polysaccharide, as a delivery system for the ocular administration of hydrophilic and hydrophobic antibiotics. </li></ul>
  30. 34. CONCLUSION & FUTURE OUTLOOK <ul><li>Ocular drug delivery has to overcome unique barriers. </li></ul><ul><li>Development of ophthalmic drug delivery systems at present include polymeric gels, colloidal systems, cyclodextrins, collagen shields. </li></ul><ul><li>Activated gel-forming systems are preferred to hydro gels. </li></ul><ul><li>Colloidal systems have convenience in maintaining drug activity at the site of action & is suitable for poorly soluble drugs. </li></ul><ul><li>New tendency of research in ophthalmic drug delivery system is directed towards combination of several drug delivery technologies. </li></ul>
  31. 35. Reference <ul><li>S.P.Vyas Roop K.Khar ; Controlled Drug Delivery, concepts and advances, Pg No: 383-410. </li></ul><ul><li>Remington & Gennaro ; The Science & Practice Of Pharmacy. Mack Publication Company. Easton, Pennsylvania. Pg. No. 1563-1567. </li></ul><ul><li>Web Sites: </li></ul><ul><li>www.vision-care-guide.com </li></ul><ul><li>www.google/images/eye/anatomy& physiology </li></ul>
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