Download Free Medical Ocular Pharmacology PowerPoint Presentation

Ocular Pharmacology PowerPoint Presentation

DOWNLOAD MEDICAL POWERPOINT PRESENTATION

About This Presentation

Description : Check out this medical presentation on Pharmacology, which is titled "Ocular Pharmacology-I", to know about pharmacokinetics and pharmacodynamics of ocular drugs, ocular routes of drug administration, and topical antibiotic and cycloplegic agents.

Tags : Pharmacology, Ocular Pharmacology, pharmacokinetics, pharmacodynamics

Published on : Jul 18, 2021 | Views : 3176 | Downloads : 8

Shareable Url :

Embed Code :

Comment

Transcript

Slide 1-

Ocular Pharmacology-I Dr. Ajai Agrawal Additional Professor Department of Ophthalmology A.I.I.M.S., Rishikesh
Slide 2-

Learning Objectives At the end of this class students shall have a basic understanding of : pharmacokinetics and pharmacodynamics of ocular drugs Ocular routes of drug administration Topical antibiotic and cycloplegic agents 2
Slide 3-

Overview 3
Slide 4-

Anatomy of Eye 4
Slide 5-

Tear Film 5
Slide 6-

6
Slide 7-

Pharmacodynamics It is the biological and therapeutic effect of the drug (mechanism of action) Most drugs act by binding to regulatory macromolecules, usually neurotransmitters or hormone receptors or enzymes If the drug is working at the receptor level, it can be agonist or antagonist If the drug is working at the enzyme level, it can be activator or inhibitor 7
Slide 8-

Pharmacokinetics It is the absorption, distribution, metabolism, and excretion of the drug A drug can be delivered to ocular tissue as: Locally: Eye drop Ointment Periocular injection Intraocular injection Systemically: Orally IV 8
Slide 9-

Pharmacokinetics of Ocular Drugs Classical pharmacokinetic theory based on systemically administered drugs does not fully apply to all ophthalmic drugs Topical route – most commonly used 9
Slide 10-

Absorption Rate & extent of absorption of topically instilled drugs depends upon – “Drug penetration into the eye is approximately linearly related to its concentration in the tear film.” Time the drug remains in the cul-de-sac & precorneal tear film Elimination by nasolacrimal drainage Drug binding to tear proteins Drug metabolism by tear & tissue proteins Diffusion across cornea & conjunctiva 10
Slide 11-

Distribution Transcorneal absorption Accumulation in aqueous humor Distribution to intraocular structures Trabecular meshwork pathway Distribution to systemic circulation 11
Slide 12-

Distribution Melanin binding of certain drugs – - Eg: 1. Mydriatic effect of alpha adrenergic agonists slower in onset - darkly pigmented irides compared to those with lightly pigmented irides 2. Atropine’s mydriatic effect – long lasting in non-albino rabbits than in albino rabbits 3. Accumulation of chloroquine in retinal pigment epithelium – Bull’s eye maculopathy 12
Slide 13-

Metabolism Enzymatic biotransformation of ocular drugs- significant Esterases – particular interest Eg: Development of prodrugs for enhanced ocular permeability Dipivefrin hydrochloride Latanoprost 13
Slide 14-

14
Slide 15-

Drug Delivery in Eyes Topical Periocular Intraocular Systemic drop ointment gel Soft contact lens Subconjunctival Subtenon Peribulbar Retrobulbar Intracameral Intravitreal Oral intravenous Intramuscular
Slide 16-

Ocular Routes of Drug Administration 16
Slide 17-

Factors influencing local drug penetration into ocular tissue Drug concentration and solubility: higher concentration -- better penetration e.g pilocarpine 1-4% but limited by reflex tearing Viscosity: addition of methylcellulose and polyvinyl alcohol increases drug penetration by increasing contact time with cornea and altering corneal epithelium Lipid solubility: higher lipid solubility- more penetration 17
Slide 18-

Factors influencing local drug penetration into ocular tissue Surfactants: preservatives alter cell membrane in cornea and increase drug permeability e.g. benzylkonium and thiomersal pH: the normal tear pH is 7.4 If drug pH is much different, this will cause reflex tearing Drug tonicity: when an alkaloid drug is put in relatively alkaloid medium, the proportion of the uncharged form will increase, thus more penetration Molecular weight and size 18
Slide 19-

TOPICAL Drop (Gutta)- simplest and most convenient mainly for day time use 1 drop=50 microlitre Conjuctival sac capacity=7-13 micro liter so, even 1 drop is more than enough Method hold the skin below the lower eye lid pull it forward slightly INSTILL 1 drop measures to increase drop absorption: -wait 5-10 minutes between drops -compress lacrimal sac -keep lids closed for 5 minutes after instillation 19
Slide 20-

Ointments Increase the contact time of ocular medication to ocular surface, thus better effect It has the disadvantage of blurring vision The drug has to be highly lipid soluble with some water solubility to have maximum effect as ointment 20
Slide 21-

Peri-ocular injections They reach behind iris-lens diaphragm better than topical application E.g. subconjunctival, subtenon, peribulbar, or retrobulbar This route bypass the conjunctival and corneal epithelium which is good for drugs with low lipid solubility (e.g. penicillins) Also steroids and local anesthetics can be applied this way 21
Slide 22-

Periocular Subconjunctival - To achieve higher concentration Drugs which cannot penetrate cornea due to large size Penetrate via sclera Subtenon—Ant. Subtenon– diseases anterior to the lens Post. Subtenon– disease posterior to the lens Retrobulbar- Optic neuritis Papillitis Posterior uveitis Anesthesia Peribulbar-- anesthesia 22
Slide 23-

Intraocular injections Intracameral or intravitreal E.g. Intracameral acetylcholine (miochol) during cataract surgery Intravitreal antibiotics in cases of endophthalmitis Intravitreal steroids in macular edema Intravitreal Anti-VEGF for DR 23
Slide 24-

Sustained-release devices These are devices that deliver an adequate supply of medication at a steady-state level E.g. Ocusert delivering pilocarpine Timoptic XE delivering timolol Ganciclovir sustained-release intraocular device Collagen shields 24
Slide 25-

Systemic drugs Oral or IV Factor influencing systemic drug penetration into ocular tissue: lipid solubility of the drug: more penetration with high lipid solubility Protein binding: more effect with low protein binding Ocular inflammation: more penetration with ocular inflammation 25
Slide 26-

Therapeutic applications of Drugs in Ophthalmology 26
Slide 27-

Common ocular drugs Antibacterials (antibiotics) Antivirals Antifungals Mydriatics and cycloplegics Antiglaucoma medications Anti-inflammatory agents Ocular Lubricants Local anesthetics Ocular diagnostic drugs Ocular Toxicology Corticosteroids NSAID’s 27
Slide 28-

Topical Antibacterial Agents Commercially Available for Ophthalmic Use H- Hypersensitivity ; D-RCD – Drug Related Corneal Deposits 28
Slide 29-

Topical Antibacterial Agents Commercially Available for Ophthalmic Use….. 29
Slide 30-

Antibacterials( antibiotics) Penicillins Cephalosporins Sulfonamides Tetracyclines Chloramphenicol Aminoglycosides Fluoroquinolones Vancomycin Macrolides 30
Slide 31-

Antibiotics Used topically in prophylaxis (pre and postoperatively) and treatment of ocular bacterial infections. Used orally for the treatment of preseptal cellulitis e.g. amoxycillin with clavulanate, cefaclor Used intravenously for the treatment of orbital cellulitis e.g. gentamicin, cephalosporin, vancomycin, Can be injected intravitrally for the treatment of endophthalmitis 31
Slide 32-

Specific antibiotic for almost each organisms Sulfonamides- Chlamydial infections like TRACHOMA INCLUSION CONJUNCTIVITIS TOXOPLAMOSIS Bacterial cell wall synthesis inhibitors- Penicillin Cephalosporins I) First generation- Gram + cocci eg cephazoline ii) Second generation —Gram – ve and antistaphylococcal— cefuroxime iii) Third generation– Gram –ve bacilli --ceftriaxones 32
Slide 33-

Side effects- allergic reaction neutropenia thrombocytopenia Amino glycosides Mainly against gram negative bacilli Bacterial protein synthesis inhibitors Gentamycin- 0.3% eye drops Tobramycin- 0.3% eye drop Neomycin— 0.3-0.5% eye drops Amikacin ----- 1% eye drops 33
Slide 34-

Tetracycline Inhibit protein synthesis active against both gram+ and gram -ve, some fungi and Chlamydia Chloramphenicol Broad spectrum ,bacteriostatic, gram+/gram-ve, Chlamydia 0.5% Eye drops, ointment 34
Slide 35-

Fluoroqinolones Most frequently used topical broad spectrum antibiotics Ciprofloxacin – 0.3% eye drops Ofloxacin - 0.3% eye drops Moxifloxacin - 0.5 % eye drops Levofloxacin and Besifloxacin eye drops 35
Slide 36-

Antibiotics Trachoma can be treated by topical and systemic tetracycline or erythromycin, or systemic azithromycin. Bacterial keratitis (bacterial corneal ulcers) can be treated by topical fortified cephalosporins, aminoglycosides, vancomycin, or fluoroquinolones. Bacterial conjunctivitis is usually self limited but topical erythromycin, aminoglycosides, fluoroquinolones, or chloramphenicol can be used 36
Slide 37-

Dacryocystitis - Infection of the lacrimal sac 37
Slide 38-

Hordeolum/ Stye – Infection of the meibomian, Zeis or Moll gland 38
Slide 39-

Conjunctivitis – Inflammatory process of the conjunctiva 39
Slide 40-

Blepharitis – Bilateral inflammatory process of the eyelids 40
Slide 41-

Antiviral Agents for Ophthalmic Use PK – Punctate Keratopathy ; H - Hypersensitivity 41
Slide 42-

Antiviral Agents for Ophthalmic Use… 42
Slide 43-

Antivirals Acyclovir- Most commonly used anti-viral 3% ointment 5 times-10-14 days 800mg oral 5 times 10-14 days Intravenous for Herpes zoster retinitis Others Idoxuridine Vidarabine Cytarabine Triflurothymidine Gancyclovir INDICATIONS HZ keratitis Viral uveitis 43
Slide 44-

VIRAL DENTRITIC ULCER 44
Slide 45-

CMV Retinitis 45
Slide 46-

Antifungal Agents for Ophthalmic Use 46
Slide 47-

ANTIFUNGAL INDICATIONS Fungal corneal ulcer Fungal retinitis/ Endophthalmitis Commonly used drugs are Polyenes damage cell membrane of susceptible fungi e.g. amphotericin B, natamycin, nystatin side effect: nephrotoxicity Imidazoles increase fungal cell membrane permeability e.g. miconazole, ketoconazole,fluconazole Flucytocine act by inhibiting DNA synthesis 47
Slide 48-

48
Slide 49-

Mydriatics and cycloplegics Dilate the pupil, ciliary muscle paralysis CLASSIFICATION Short acting- Tropicamide (4-6 hours) Intermediate- homatropine ( 24 hours) Long acting- atropine (2 weeks) Indications corneal ulcer uveitis cycloplegic refraction 49
Slide 50-

50
Slide 51-

Thank you 51