Ocular pharmacology
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Kuliah Farmakologi Blok 10 - Penglihatan
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Ocular pharmacology
- 1. M Fadhol Romdhoni Pharmacology Laboratory Faculty of Medicine, University Muhammadiyah of Purwokerto Ocular Pharmacology
- 2. Farmakodinamik • efek biologis dan terapi obat (mekanisme kerja) • Sebagian besar obat bekerja dengan mengikat makromolekul, seperti neurotransmiter, reseptor hormon atau enzim • Jika obat tersebut bekerja pada tingkat reseptor, itu bisa berupa agonis atau antagonis • Jika obat tersebut bekerja pada tingkat enzim, itu bisa menjadi aktivator atau inhibitor
- 3. Farmakokinetik • Proses absorbsi, distribusi, metabolism, dan ekskresi obat/zat • Obat dapat didistribusikan ke jaringan mata sebagai: • Obat lokal • Tetes mata • Ointment • Injeksi periocular • Injeksi intraocular • Sistemik • Oral • Intravena
- 4. Drug Delivery in Eyes Topical Periocular Intraocular Systemic drop ointment gel Soft contact lens Subconj. Subtenon Peribulbar Retrobulbar Intracameral Intravitreal oral intravenous Intramuscular
- 5. Faktor-faktor yang mempengaruhi penetrasi obat lokal ke dalam jaringan mata • Konsentrasi dan kelarutan obat • semakin tinggi konsentrasinya, semakin baik penetrasi mis. pilocarpine 1-4% • Kekentalan • penambahan metilselulosa dan polivinil alkohol meningkatkan penetrasi obat dengan meningk- atkan waktu kontak dengan kornea dan meng- ubah epitel kornea • Kelarutan terhadap lemak • membran sel epitel banyak mengandung lipid, sehingga semakin tinggi kelarutan dalam lemak maka semakin penetrasi semakin baik
- 6. • Surfaktan • bahan pengawet yang digunakan dalam sediaan okular mengubah membran sel dalam kornea dan meningkatkan permeabilitas obat mis. benzylkonium dan thiomersal • pH • pH normal air mata adalah 7,4 dan jika pH obat jauh berbeda, ini akan menyebabkan reflek pengeluaran air mata • Tonisitas • ketika obat alkaloid dimasukkan ke dalam media yang relatif al- kaloid, proporsi bentuk tidak bermuatan akan meningkat, sehin- gga lebih banyak penetrasi • Berat dan ukuran molekul Faktor-faktor yang mempengaruhi penetrasi obat lokal ke dalam jaringan mata
- 7. TOPICAL Drop (Gutta)- simplest and more 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 INSTALL 1 drop measures to increase drop absorption: -wait 5-10 minutes between drops -compress lacrimal sac -keep lids closed for 5 minutes after instillation
- 8. Ointments Increase the contact time of ocular medication to ocular surface thus better effect It has the disadvantage of vision blurring The drug has to be high lipid soluble with some water solubility to h ave the maximum effect as ointment
- 9. Peri-ocular injections They reach behind iris-lens diaphragm better than topical application E.g. subconjunctival, subtenon, peribu- lbar, or retrobulbar This route bypass the conjunctival and corneal epithelium which is good for dr ugs with low lipid solubility (e.g. penicil- lins) Also steroid and local anesthetics can be applied this way
- 10. Periocular Subconjunctival - To achieve higher concentration Drugs which can’t penetrate cornea due to large size Penetrate via sclera Subtenon— ant. Subtenon– disease ant to the Lens Post Subtenon– disease posterior to the lens Retrobulbar-Optic neuritis Papillitis Posterior uveitis Anesthesia Peribulbar-- anesthesia
- 11. Intraocular injections Intracameral or intravitreal E.g. – Intracameral acetylcholine ( miochol) during cataract su rgery – Intravitreal antibiotics in cases of endophthalmitis – Intravitreal steroid in macular edema
- 12. Sustained-release devices These are devices that deliver an adequate supply of medicat ion at a steady-state level E.g. – Ocusert delivering pilocarpine – Timoptic XE delivering timolol – Ganciclovir sustained-release i ntraocular device – Collagen shields
- 13. Common ocular drugs Antibacterials (antibiotics) Antivirals Antifungal Mydriatics and cycloplegics Antiglaucoma Anti-inflammatory agents Ocular Lubricants Ocular diagnostic drugs Local anesthetics Ocular Toxicology Corticosteroids NSAID
- 15. Antibiotics Used topically in prophylaxis (pre and postop eratively) and treatment of ocular bacterial in fections. Used orally for the treatment of preseptal cellulitis e.g. amoxycillin with clavulonate, cefaclor Used intravenously for the treatment of orbital cellulitis e.g. gentamicin, cephalosporin, vancomycin, flagyl Can be injected intravitrally for the treatment of endophthalmitis
- 16. Specific antibiotic for almost each organisms Sulfonamiodes- Chlamydial infections like TRACHOMA INCLUSION CONJUNCTIVITIS TOXOPLAMOSIS Bacterial cell wall syntheis inhibitors- Penicillin Cephalosporins I) first generation- gm + cocci eg cephazolone ii) second generation Gm –and antistaphylococcal cefuroxime iii) Third generation Gm – bacilli --ceftriaxones
- 17. Side effects- allergic reaction neutropenia thrombocytopenia Amino glycosides mainly against gm negative bacilli Bacterial protein synthesis inhibitors Gentamycin—0.3% eye drop Tobramycin- Pseudomonas 1% eye drop Neomycin—0.3-0.5% eye drop
- 18. Tetracycline Inhibit protein synthesis active against both gm+ and gm -, some fungi and Chlamydia Chloromphenicol Broad spectrum ,bacteriostatic, gm+/gm-, Chlamydia 0.5% Eye drop, ointment
- 19. Antibiotics Trachoma can be treated by topi cal and systemic tetracycline or e rythromycin, or systemic azithro mycin. Bacterial keratitis (bacterial corn eal ulcers) can be treated by topi cal fortified penicillins, cephalosp orins, aminoglycosides, vancomy cin, or fluoroquinolones. Bacterial conjunctivitis is usuall y self limited but topical erythro mycin, aminoglycosides, fluoroqu inolones, or chloramphenicol can be used
- 20. Antivirals Acyclovir 3% oinment 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
- 21. 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,fluconazile Flucytocine – act by inhibiting DNA synthesis
- 22. 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
- 23. Antiglaucoma drugs Beta blockers- Selective – betaxolol Non selective- timolol reduces aqueous humour production Reduces IOP Side effect systemic bradycardia, Sweating anxiety ocular Irritaion Frontal headache Iris cyst Follicular conjuctivitis
- 24. Carbonic anhydrase inhibitors Systemic topical acetazoamide Dorzolamide brinzolamide Mechanism of action---- reduce aqueous humour formation Side effect Paresthesiae Frequent urination GI disturbances Hypokalamia
- 25. Hyperosmotic agent--- iv mannitol when IOP is very high 60-70 Prostaglandins Latanoprost (0.005% eye drop) increased aqueous out flow Reduced IOP Side effect– conjunctival redness, iris and periocular pigmentation hypertrichosis, darkening of iris
- 27. Corticosteroids CLASSIFICATION Short acting hydrocortisone, cortisone, prednisolone Intermediate acting Trimcinolone, Fluprednisolone Long acting Dexamethasone ,betamethasone
- 28. Indications Topical allergic conjunctivitis, scleritis, uveitis, allergic keratitis after intraocular and extra ocular surgeries Systemic (pathology behind the LENS) Posterior uveitis Optic neuritis corneal graft rejection NEVER GIVE STEROID IF YOU ARE SUSPECTING ACTIVE INFECTION
- 30. Side effects OCULAR glaucoma cataract activation of infection delayed wound healing
- 31. Side effect SYSTEMIC Peptic ulcer Hypertension Increased blood sugar Osteoporosis Mental changes Activation of tuberculosis and other infections
- 32. Pre-requisite / prasyarat BP Blood sugar Mantoux TC,DC,ESR CXR
- 33. NSAIDS Topical use flurbiprofen indomethacine ketorolac Indications episcleritis and scleritis uveitis CME PRE operatively to maintain dilation of the pupil
- 34. Ocular Lubricants Indication ocular irritations in various diseases Dry eyes Commonly available commercial tear substitutes REFRESH TEARS TEAR PLUS MOISOL OCCUWET DUDROP
- 35. Ocular diagnostic drugs Fluorescein dye – Available as drops or strip s – Uses: stain corneal abrasio ns, applanation tonometry, detecting wound leak, NL D obstruction, fluorescein angiography – Caution: • stains soft contact lens • Fluorescein drops can be contaminated by Pseudo monas sp.
- 36. Ocular diagnostic drugs Rose bengal stain – Stains devitalized epithelium – Uses: severe dry eye, herpetic keratitis
- 37. Local anesthetics topical – E.g. propacaine, tetracaine – Uses: applanation tonometry, goniscopy, re moval of corneal foreign bodies, removal of sutures, examination of patients who cannot open eyes because of pain – Adverse effects: toxic to corneal epithelium, allergic reaction rarely
- 38. Local anesthetics Orbital infiltration – peribulbar or retrobulbar – cause anesthesia and akinesia for intraocula r surgery – e.g. lidocaine, bupivacaine
- 40. Complications of topical administration Mechanical injury from the bottl e e.g. corneal abrasion Pigmentation: epinephrine- adrenochrome Ocular damage: e.g. topical anes thetics, benzylkonium Hypersensitivity: e.g. atropine, ne omycin, gentamicin Systemic effect: topical phenylep hrine can increase BP
- 41. Amiodarone A cardiac arrhythmia drug Causes optic neuropathy (mild decreased vision, visual fie ld defects, bilateral optic disc swelling) Also causes corneal vortex keratopathy (corneal verticillat a) which is whorl-shaped pigmented deposits in the corn eal epithelium
- 42. Digitalis • A cardiac failure drug • Causes chromatopsia (objects appear yellow) with overdose
- 43. Chloroquines • E.g. chloroquine, hydroxychloroquine • Used in malaria, rheumatoid arthritis, SLE • Cause vortex keratopathy (corneal verticillata) which is usually asymptomatic but can present with glare and photophobia • Also cause retinopathy (bull’s eye maculopathy)
- 44. Chorpromazine • A psychiatric drug • Causes corneal punctate epithelial opacities, lens surface opacities • Rarely symptomatic • Reversible with drug discontinuation
- 45. Ethambutol • An anti-TB drug • Causes a dose-related optic neuropathy • Usually reversible but occasionally permanent visual damage might occur
- 46. Sekian File dapat diunduh di www.romdhoni.com