Ophthalmic Drugs PHAR1059 2024-2025 PDF

Ophthalmic Drugs PHAR1059 – 2024-2025 General Administration Concepts  Very few systemic drugs can cross the blood-eye barrier and reach therapeutic levels in eye tissue.  Ophthalmic drugs are administered locally. Advantage of local administration includes OPHTHALMIC 1. Agent a...

Ophthalmic Drugs PHAR1059 – 2024-2025 General Administration Concepts  Very few systemic drugs can cross the blood-eye barrier and reach therapeutic levels in eye tissue.  Ophthalmic drugs are administered locally. Advantage of local administration includes OPHTHALMIC 1. Agent administered directly to site of action. DRUGS - is more immediate 2. Effect GENERAL 3. Small doses can be used 4. Systemic effect is minimal to none General Administration Concepts There are 3 methods of administering drugs locally to the eye 1. TOPICAL  Drugs applied to the surface of the eye in the form of drops, lotions, ointments or impregnated filter paper.  Drugs enter the eye through the cornea. 2. PERIOCULAR  Drugs place alongside and external to the eyeball, allowing diffusion into the eye 3. INTROCULAR  Drugs instilled into either the anterior chamber (intracameral injection) or the posterior cavity (intra-vitreal injection). OPHTHALMIC DRUG CLASSES 1. Anti-glaucoma (Miotics & Mydriatics) 2. Anaesthetics 3. Antihistamines and Mast Cell Stabilizers 4. Corticosteroids 5. NSAIDs 6. Antimicrobials  We have covered most of the MEC of these drugs in previous Sem 3 lectures and in semester 2 – now apply to administration to the eye ANTI-GLAUCOMA DRUGS ANTI-GLAUCOMA DRUGS There are 3 classes of anti-glaucoma drugs 1. Miotics  Cholinergic – Replacing substance  Cholinergic – Blocking specific receptors 2. Mydriatics  Adrenergic (Sympathomimetic) 3. Others  Anti-adrenergic  Carbonic anhydrase inhibitors  Osmotic diuretics  Prostaglandin agonists ANTI-GLAUCOMA DRUGS - MIOTICS Cholinergic Agents – (Direct Acting) 1. Pilocarpine (Isopto Carbine, Pilocar) 2. Carbachol (Carbastat) Mechanism of Action  Ach or ACH-like substance that directly increases cholinergic activity  Activate the cholinergic receptors to produce dilation of trabecular meshwork ANTI-GLAUCOMA DRUGS - MIOTICS Cholinergic Agents – (Direct Acting) Therapeutic Effect  Miosis (Pupil Constriction)  Increase outflow of aqueous humor in glaucoma patients  Causes the reabsorption of more aqueous humor → ↓ IOP Adverse Effect  The drug may produce temporary blurred vision (cycloplegia) and accommodation defects (ability to change focus) ANTI-GLAUCOMA DRUGS - MIOTICS Cholinergic – (Indirect Acting - Cholinesterase Inhibitors) 1. Physostigmine salicylate (Eserins sulphate) Mechanism of Action  Inhibits the breakdown of ACh by Cholinesterase  This increases the amount of available in the PNS The Therapeutic Effect and Adverse Effect is the same as the direct acting Miotics - Textbook Fig 57.8 & 57.9 ANTI-GLAUCOMA DRUGS - MYDRIATICS Adrenergic 1. Apraclonidine (lopidine) 2. Brimonidine (Alphagan) Mechanism of Action  Alpha-2 adrenergic agonist  Mimic the Sympathetic neurotransmitters (epi, norepinephrine)  Stimulates SNS ➔ contracts pupil muscles ➔ increases pupil size/dilates (mydriasis) ANTI-GLAUCOMA DRUGS - MYDRIATICS Therapeutic Effect  Causes the pupil to increase which reduces intraocular pressure Indication  Used to treat open-angle glaucoma and ocular hypertension. Adverse Effect  Photosensitivity Mydriatics – Fig 57.11 ANTI-GLAUCOMA DRUGS Anti-Adrenergics (Beta Blockers) Mechanism of Action  Block beta receptors in the ciliary body of the eye  Beta receptors are responsible for the production of aqueous humor Therapeutic Effect  Reduction of the production of aqueous humor  Less fluid = less IOP Advantages!  Does NOT alter pupil size so does not cause cycloplegic effects  Dose of beta blockers used for ophthalmic treatment are generally not high enough to cause general circulation effects. ANTI-GLAUCOMA DRUGS Anti-Adrenergics (Beta Blockers) 1. Betaxolol  Beta-1 selective blocker  Indications  chronic open-angle glaucoma and ocular hypertension. 2. Timolol  Indications  Elevated IOP or ocular hypertension.  Patient who cannot use beta blockers and use carbonic-anhydrase or osmotic diuretics as alternatives  Also increases outflow ANTI-GLAUCOMA DRUGS Carbonic Anhydrase Inhibitors 1. Acetazolamide (Diamox, Sequels) 2. Methazolamine (Apo-methazolamide) 3. Brinzolamide (Azopt) 4. Dorzolamide (Trusopt) Mechanism of Action  Carbonic Anhydrase is and enzyme that is essential for aqueous humor production  These drugs inhibit (block) carbonic anhydrase and in turn reduce the production of aqueous humor  Like Beta Blockers – no pupil changes (no cycloplegic effects) ANTI-GLAUCOMA DRUGS Carbonic Anhydrase Inhibitors Therapeutic Effects  Decreases production of aqueous humor by inhibiting enzyme  Decreasing IOP in glaucoma patients = DIURETIC EFFECT Indications  Second choice if beta blockers are contraindicated or not effective.  More effective when used to treat open-angle glaucoma. Adverse Event  Allergy risk  Sulphonamide based drug = risk of allergic reaction ANTI-GLAUCOMA DRUGS Osmotic Diuretics 1. Mannitol (Osmitrol) 2. Glycerin Mechanism of Action  Osmotic agent  Large molecules that do not cross membranes easily  Cause a change in concertation gradient that then draws fluid (H2O) from the vitreous humor Therapeutic Effect  Reduce volume of vitreous humor = decreased intraocular pressure ANTI-GLAUCOMA DRUGS PROSTAGLANDIN ANALOG 1. Latanoprost (Xalantan) 2. Bimatoprost (Limigan) 3. Traprost (Travatan) Mechanism of Action  Analog = same as a prostaglandin  PGAs bind to prostaglandin F (FP) receptors in the eye  When stimulated prostaglandin receptors in the eye will relax the ciliary muscles in the eye ANTI-GLAUCOMA DRUGS PROSTAGLANDIN ANALOG Therapeutic Effect  Increases out flow and congestion in the trabecular meshwork  Results in decreased IOP Indication  First-line agents for glaucoma patients who do not respond to beta- adrenergic blocking Administration considerations  Should be given at night  Single dosing (daily) – long half life ANTI-GLAUCOMA DRUGS PROSTAGLANDIN ANALOG Adverse effect  Heighten pigmentation (brown iris)  Can turn other eye colours to brown permanently (10-15%)  Cycloplegia  Thickening of Eyelashes  Local irritation and stinging of the eye  prostaglandins are and inflammatory chemical mediator OPHTHALMIC DRUG CLASSES 1. Anti-glaucoma (Miotics & Mydriatics) 2. Anaesthetics 3. Antihistamines and Mast Cell Stabilizers 4. Corticosteroids 5. NSAIDs 6. Antimicrobials  We have covered most of the MEC of these drugs in previous Sem 3 lectures and in semester 2 – now apply to administration to the eye PHAR1059 2023 ANAESTETICS 1. Tetracaine (Pontocaine) 2. Lidocaine 3. Proparacaine (Ophthaine, Opthetic) Mechanism of Action  Block pain by stabilizing neuronal membranes  Less permeable to ions and do not transmit nerve impulses Indication  Used for diagnostic and therapeutic purposes such as:  Tonometry  Removal of foreign bodies  Removal of sutures  Minor eye surgery PHAR1059 2023 ANAESTETICS Nursing Considerations  Onset of anesthesia is fast  Within about 30 seconds of application  Duration is relatively short  Last about 30 min  Short term use only  Not for self administration  Known allergy is contraindication ANTIHISTAMINES & MAST CELL STABILIZERS Cromolyn (Opticrom) = Mast cell stabilizer  Inhibits the release of chemical mediators from mast cells  Indicated for use of vernal keratoconjunctivitis (seasonal) Olopatadine hydrochloride (Patanol®, Pataday) = Antihistamine  Antihistamines block H1 receptors  Indicated for the alleviation of the symptoms due to use of allergic conjunctivitis.  CORTICOSTERIODS 1. Betamethasone (Betnesol) 2. Dexamethasone (Maxidex) 3. Fluorometholone 4. Hydrocortisone (Cortamed) 5. Prednisolone (Pred-Forte, Predair-A)  Indicated for treatment of allergic and inflammatory ophthalmic disorders of conjunctiva, cornea, and anterior segment of the eye.  Are available as topical solutions, suspensions, or ointments  NSAIDs Similar meds covered in Semester 2 are available for ophthalmic use to treat mild to moderate inflammatory issues 1. Flurbiprofen Na (Ocufen, Acular)  Used to treat conjunctivitis and seasonal allergic ophthalmic pruritis (itching) 2. Suprofen (Proenal)  Used to treat conjunctivitis and seasonal allergic ophthalmic pruritis 3. Diclofenac (Diclotec, Novo-Difenac)  Used to treat postop. inflammation after cataract extraction. 4. Ketorolac Tromethamie  Used to treat conjunctivitis and seasonal allergic ophthalmic pruritis PHAR1059 2023 ANTIBIOTICS 1. Sulphonamides (sulfacetamide (Cetamide, Diosulf))  used to treat gram +ve and gram –ve infection. 2. Macrolides (Erythromycin)  prevents neonatal gonococcal or chlamydial conjunctivitis 3. Aminoglycosides (Gentamycin, Tobramycin and Moxifloxacin)  prevents neonatal gonococcal or chlamydial conjunctivitis, E coli infection and a wide range of gram –ve bacterial infection.  Note that some antibiotics can be combined with steroids for inflammation and infection neomycin and tobramycin are typically found in these combo drugs  ANTIVIRALs 1. Idoxuridine (Stoxil, Herplex)  treat herpes simplex virus keratitis 2. Trifluridine (Viroptic)  used to treat herpes simplex virus keratoconjunctivitis 3. Vidarabine (Vira-A)  used to treat herpes simplex infection.  ANTIFUNGALS 1. Natamycin (Natacyn)  used to treat fungal blepharitis, conjunctivitis and keratitis. 2. Verteportin (Visudyne)  used to treat ocular histoplasmosis and age-related macular degeneration. Nursing Considerations  Assess condition of eye, conjunctiva  Correct technique- never directly on eye, always to conjunctiva  Ensure solution is clear and not expired, shake before using  Keep tip sterile & do not touch to eye  Remove excess meds and apply pressure to inner canthus for 1 minutes  Awareness of side effects  Avoid touching/rubbing eyes after  Do not use contact lens while having treatment  Report signs of eye infection, eye pain, vision changes