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APPROACHES OF DRUG DELIVERY TO EYES
 

APPROACHES OF DRUG DELIVERY TO EYES

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Eye diseases are commonly encountered in day to day life, which are cured or prevented through the conventionally used dosage forms. Delivery to the internal parts of the eye still remains troublesome ...

Eye diseases are commonly encountered in day to day life, which are cured or prevented through the conventionally used dosage forms. Delivery to the internal parts of the eye still remains troublesome due to the anatomical and protective structure of the eye. Drugs may be delivered to the eye through the application of four primary modes of administration: topical, systemic, intravitreal, and periocular.

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APPROACHES OF DRUG DELIVERY TO EYES APPROACHES OF DRUG DELIVERY TO EYES Presentation Transcript

  • 1 APPROACHES OF DRUG DELIVERY TO EYES
  • 2 CONTENTS • • • • • • • • • • INTRODUCTION ANATOMY AND PHYSIOLOGY OF EYE BARRIERS FORMULATION CONSIDERATIONS IDEAL CHARACTERISTICS DRUG DELIVERY SYSTEMS EVALUATION ADVANTAGES AND DISADVANTAGES CONCLUSION REFERENCES
  • 3 INTRODUCTION • Eye diseases are commonly encountered in day to day life, which are cured or prevented through the conventionally used dosage forms like eye drops, ointments, etc., Ocular drug delivery systems are intended for installation into the cul-de-sac, i.e., the space between the eye ball and the eye lids. Delivery to the internal parts of the eye still remains troublesome due to the anatomical and protective structure of the eye. Drugs may be delivered to the eye through the application of four primary modes of administration: topical, systemic, intravitreal, and periocular.
  • 4 ANATOMY AND PHYSIOLOGY OF EYE
  • 5 BARRIERS FOR DRUG ABSORPTION • Tears • Cornea • Conjuctiva • Sclera • Retina
  • 6 FORMULATION CONSIDERATIONS • Physicochemical characteristics polymers. • Buffering capacity and pH. • Instillation volume. • Osmotic pressure. of drug and
  • 7 Ideal characteristics of ocular drug delivery system • Good corneal penetration. • Prolong contact time with corneal tissue. • Non irritative and non toxic. • Good rheological properties. • Non greasy • Patient compliance.
  • DRUG DELIVERY SYSTEMS TO EYE: IMPLANTS DENDRIMERS IONTOPHORESIS MICROEMULSION MICRONEEDLE NANOSUSPENSION CONTACT LENSES 8
  • 9 1.CONVENTIONAL SYSTEMS • EYE DROPS: To prolong the retention time of topically applied drugs, anterior DDSs for eye-drops utilizing interaction physiological between drug environment carrier of (excipients) cornea and/or and sub- conjunctiva are being developed. These are administered in the form of Solutions, Emulsion and Suspension eye drops and are used only for anterior segment disorders.
  • 10 •OINTLENTS AND GELS Prolongation of drug contact time with the external ocular surface can be achieved using ophthalmic ointment vehicle but, the major drawback of this dosage form like, blurring of vision and blinking of eyelids can limits its use. These products will stay on eyes longer than eye drops. •INSERTS Ocular insert are sterile preparation that prolong residence time of drug with a controlled release manner and negligible or less affected by naso-lacrimal damage. The ocular inserts maintain an effective drug concentration in the target tissues and yet minimize the number of applications.
  • 11 2.VESICULAR SYSTEMS • LIPOSOMES: Liposomes are vesicles composed of lipid membrane enclosing an aqueous volume. These structures are formed simultaneously when a matrix of phospholipids are agitated in an aqueous medium to disperse the two phases. They are having an intimate contact with the corneal and conjunctival surfaces which is desirable for drugs that are poorly absorbed. • NIOSOMES AND DISCOMES : Niosomes are nonionic surfactant vesicles that have potential applications in the delivery of hydrophobic or amphiphilic drugs. Discomes are discoidal vesicles and may act as potential drug delivery carriers by releasing the drug in a sustained manner at the ocular site.
  • 12 •PHARMACOSOMES: Drugs possessing a free carboxyl group or an active hydrogen atom can be esterified to the hydroxyl group of a lipid molecule, thus generating an amphiphilic prodrug. This amphiphilic prodrug is converted to pharmacosomes on dilution with water. pharmacosomes show greater shelf stability, facilitated transport across the cornea, and a controlled release profile.
  • 13 3.CONTROLLED RELEASE • IMPLANTS: implants are effective drug delivery system for chronic ocular diseases like cytomegalovirus (CMV), retinitis. Intravitreal implants of fluocinolone acetonide were developed for the treatment of posterior segment. • DENDRIMERS: Dendrimers are repetitively branched molecules and can be successfully used for ocular drug administration and have better watersolubility, bioavailability and biocompatibility.
  • 14 •IONTOPHORESIS: Iontophoresis is a noninvasive technique for ocular drug delivery. In iontophoresis the drug solution is in contact with the cornea in an eye-cup bearing an electrode and the diffusion of drug occurs by electrical potential difference. •MICROEMULSION: Microemulsion is dispersion of water and oil stabilized using surfactant and co-surfactant to reduce interfacial tension and usually characterized by small droplet size(100 nm), higher thermodynamic stability and clear appearance. They reduce the frequency of administration as compared to the conventional systems.
  • 15 •NANOSUSPENSION: Nanosuspensions have emerged as a promising strategy for the efficient delivery of hydrophobic drugs because they enhanced not only the rate and extent of ophthalmic drug absorption but also the intensity of drug action with significant extended duration of drug effect. •CONTACT LENSES: Water soluble drugs soaked in drug solutions can be absorbed through Contact lenses. The drug saturated contact lenses are placed in the eye which releases the drug in eye for a long period of time. For prolongation of ocular residence time of the drugs, hydrophilic contact lenses can be used.
  • 16 4.PARTICULATE SYSTEMS (NANOPARTICLES AND MICROPARTICLES) • Nanoparticles are prepared using bioadhesive polymers to provide sustained effect to the entrapped drugs. An optimal corneal penetration of the encapsulated drug was reported in presence of bioadhesive polymer chitosan. • Microemulsions have a transparent appearance, with thermodynamic stability and a small droplet size in the dispersed phase (aqueous and nonaqueous phase) (<1.0μm). Microspheres of poly lacto gylcolic acid (PLGA) are prepared for topical ocular delivery.
  • 17 5.ADVANCED DRUG DELIVERY SYSTEMS • Several kinds of viruses including adenovirus, retrovirus, adeno-associated virus, and herpes simplex 140virus, have been manipulated for use in gene transfer and gene therapy applications. The advanced delivery systems such as gene delivery, SiRNA, stem cells that prolong the contact time of the dosage form with the surface of the eye and facilitate noninvasive administration.
  • 18 Evaluation of ocular drug delivery system • Thickness of the film. • Drug content. • Irritancy test. • Percentage moisture loss. • In vitro drug release.
  • 19 ADVANTAGES • Localized drug delivery is possible. • Drops are easy to apply and have good patient acceptance. • Intravitreal , periocular sub-conjuctival injections improve drug absorption and have no systemic toxicity. • Micro particles , Nanoparticles, liposomes increase half life of drug. • ocular inserts increased ocular residence releasing drugs at a slow and constant rate.
  • 20 DISADVANTAGES • Physical instability of the dosage form. • Frequent administration reqired with conventional systems. • Leaking of entrapped drug.
  • 21 CONCLUSION • Ocular drug delivery systems provide local as well as systemic delivery of the drugs. The novel advanced delivery systems offer more protective and effective means of the therapy for the nearly inaccessible diseases or syndromes of eyes. Further developments are preferable which will eliminate the cons of these available advanced delivery systems and acceptable with the regulatory authorities as well. readily
  • 22 REFERENCES • Text book of pharmaceutical sciences by Remington. • Novel and controlled drug delivery by N.K Jain. • Patel Vishal, Agrawal Y.K. CURRENT STATUS AND ADVANCED APPROACHES IN OCULAR DRUG DELIVERY SYSTEM, Journal of Global Trends in Pharmaceutical Sciences, Vol.2, Issue 2, pp -131-148.
  • 23