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Jane Goodwin BSc, MSc Nurse Practitioner Drugs and the Eye A&P A&P Pharmacology • A solution is a liquid vehicle for drug delivery to the eye. • Solutions have a shorter contact time. • Drops drain into lacrimal apparatus, into the nose and are absorbed systemically. • Drops needs to be sterile therefore free from bacteria, viruses, and fungi. • Preservatives are added to inhibit the multiplication of organisms. • Some solutions oxidise when exposed to air which can alter their chemistry. • The shelf life of drops are 1 month •Preservative free drops are supplied in single dose units ‘Minims’ and used once • Most eye solutions are expressed as ‘per cent’. This translate to grams / 100ml. EG – 0.5% Chloramphenicol = 500mg of Chloramphenicol in 100ml of solution. • Advantages of administering the drug locally is that is delivers the agent directly to the site of action. • Its effects are more immediate. • Smaller doses are used. • Systemic side effects are minimised. Administration • Locally – direct into lower eye lid. Subconjunctival injection – space between conj and sclera Retrobulbar Injection - into muscle cone behind the eye • Peripubulbar – into space around the eye • Intraocular – into the eye eg Anterior Chamber Intraocular Lens •Contact lens – impregnated and placed on cornea Edge of lens Absorption • Drugs applied topically enter the eye through the cornea • There are 5 layers to the Cornea Descemet’s Membrane Internal Layer Endothelium • The outer most layer have a high lipid content (lipophilic) • The innermost layer have a high water content (Hydrophilic) • Drugs therefore have to require both lipophilic and Hydrophilic properties • PH of eye drops range between 3.5 – 10.5 which is to aid absorption • Factors that can influence absorption include trauma to the cornea – increasing the amount absorbed • Drugs can also bind to contact lenses therefore reducing their effectiveness and cause damage to the contact lens Other factors affecting absorption • Drops can be lost from the eye before they cross the cornea. Occlude Inner Canthus Types • • • • • • • • • • Antibiotics Antihistamines Anti-virals Mydriatics – dilation of pupil 2 types – parasympatholytic & Sympathomimetic Miotics – constrict the pupil Glaucoma drugs -Carbonic anhydrase inhibitors, Betablockers, Alpha 2 agonists Steroids Local anaesthetics Diagnostic Tear Replacement Mydriatics - are used to dilate the pupil for the following reasons • To examine the retina • To maintain dilatation of the pupil in uveitis, with corneal ulcers, severe corneal abrasions and after surgery • To break down posterior synaechiae in uveitis • To allow a cataract to be extracted and retinal surgery • Refraction in children 2 types • Parasympatholytics – which cause mydriasis and cycloplegia (relaxing circular iris muscle causing paralysis of the ciliary muscles) E.g. atropine, tropicamide and cyclopentolate • Sympathomimetics - mydriasis (stimulating the radial muscle of the iris to contract causing the pupil to dilate) E.g. adrenaline and phenylephine Side Effects and Cautions • Causes blurred vision therefore driving not advised • Systemic absorption can occur causing anticholinergic effects such as tachycardia, dizziness, dry mouth, constipation and hypertension • Due to risk of systemic absorption should be used with caution in people with hypertension, heart disease and thyrotoxicosis • Can cause a rise in intra ocular pressure (IOP) • Contraindicated in glaucoma especially narrow angle glaucoma • Contra-indicated with MAOI’s (monoamine oxidase inhibitors) – risk of hypertensive crisis Miotics • Miotic drugs constrict the pupil and ciliary muscle which opens up the drainage channel for aqueous flow. It main use is in the treatment of Acute Glaucoma • Pilocarpine 1% 2% and 4% (most common) Acute Glaucoma IS SIGHT THREATENING! Is a sudden rise in intra ocular pressure. This is caused by an acute blockage in the drainage system – stopping the aqueous humour drain from the eye. Symptoms include a red painful eye, reduced vision, nausea, headache and can be in one or both eyes. Normal Flow Acute blockage Miotics - Cautions • Causes - Headache/browache in long term use.. Usual burning itchy and sensitivity with drops. • Blurred vision and restricted vision - • Patient on long term treatment need monitoring for field s and IOP’s. • Avoid in conditions where a miosed pupil would be undesirable ie Iritis and Uvietis Chronic Open Glaucoma • The angle is open – but other parts of the drainage system can be affected. • Slow onset, irreversible sight loss, hereditary, more common in elderly and Afro-Caribbean's • Caused by a persistent low grade rise in intraocular pressures (normal readings are between10 - 21mmHg). Therefore readings above 22 - 35 mmHg may require monitoring and treatment. • It causes damage to the retinal nerve fibres known as cupping of the disc making the disc pale and a change in shape. Circulation of Aqueous = problem with aqueous drainage Other Glaucoma Drugs • • • • • • Carbonic anhydrase inhibitors Beta blockers Alpha 2 agonists Prostaglandin analogues Sympathomimetics Combinations of the above i.e. Carbonic anhydrase inhibitors and Beta blockers Carbonic anhydrase inhibitors • Carbonic anhydrase is an enzyme necessary for the production of aqueous. These drugs therefore reduce the production of aqueous. • Uses - Acute, Chronic and secondary Glaucoma • Ocular SE – Local eye irritation and taste disturbance • Systemic SE –drowsiness, GI, nausea, upset potassium levels and is a weak diuretic • Types – Oral and IV -Acetazolamide (Diamox) not used long term mostly in acute cases • Examples - Topical – Dorzolamide (Trusopt) and Brinzolamide (Azopt) Beta Blockers • Are relatively safe, efficacious and usually first line treatment. • Work by affecting the production of aqueous in the ciliary body and increase the outflow of aqueous in trabeculae meshwork • Uses – primary open angle glaucoma • Ocular SE – dry eyes, blurred vision, eye irritation • Systemic SE – bronchospasm in asthmatics, bradycardia and can mask manifestations of hypoglycaemia • Examples – Timolol (Timoptil), Betaxolol (Betoptic), Carteolol (Teoptic) and Levobunolol (Betagan). Alpha 2 Agonists • Is used as add on therapy when beta blockers are not enough to reduce IOP or when B’blockers are contraindicated. • Works by enhancing drainage from the eye and decreasing production of aqueous. • Uses – primary open angle glaucoma and pre op • Ocular SE – dry eyes, blurred vision, eye irritation and stinging • Systemic SE – Headache, changes in heart rate, rhythm an BP as well as anxiety and tremor • Examples – Apraclonidine (Iopidine) and Brimonidine (Alphagan) Prostaglandin Analogues • Work by increasing uveoscleral outflow • Uses – open angle glaucoma and *ocular hypertension • Ocular SE – brown colour changes in the iris and lengthening of the eyelashes • Examples – Bimatoprost (Lumigan) and Latanoprost (Xalatan) • *NB – ocular hypertension is when the IOP is normal but there is signs of the disease from the visual field tests and optic disc defects. Sympathomimetics • Dipivefrine is a pro drug of adrenaline. It is claimed to pass more rapidly than adrenaline through the cornea and is then converted to the active form. • Works by increasing the outflow of aqueous through the trabecular meshwork. • It is contra indicated in angle closure glaucoma because it is a mydriatic (dilating drug) • Ocular SE – severe smarting and stinging • Systemic SE – caution with pt’s with hypertension and heart disease. Tunnel Vision Coffee Time ! Microbiology of the eye Micro-organisms can gain access as a result of:• • • • • • • • Direct Contact e.g. Herpes simplex Air-Bourne infections Insect-Bourne infections e.g. Trachoma Migration of bacteria from nasopharynx Trauma Infected contact lenses Infected eye drops and lotions Infected instruments Conjunctivitis – most common cause of Red Eye Types of conjunctivitis • • • • • Bacterial Viral Allergic Secondary Chronic Bacterial Conjunctivitis • Acute onset • Bilateral • Red, gritty, sore, puffy lids and purulent discharge • Resolves within 5-10 days • Rx G.Chlor or Fusidic acid Viral • • • • Acute onset Related to other URTI Likely to be Unilateral Red, gritty sore, Watery discharge • Corneal staining with Fluorescien • Diagnosis difficult in Primary Care therefore refer a unilateral red eye if no improvement within 48hrs of Rx • Last for 3 -4 weeks Allergic • • • • • Acute onset Bilateral Hx of exposure to allergens Hx Atopy or Fhx Sx – very itchy,watery, chemosis (jelly like) of conj, puffy lids, follicles on Tarsal Plate (under eye lid) • Responds to antihistamines, remove from cause • Should respond immediately to Rx • Prophylactic treatment recommended. Drugs for allergic conjunctivitis • Topical antihistamine drops (H1 antagonists) – antazoline, azelastine and levocabastine provide rapid relief and can be used for up to 4/52. • If prolonged relief is required a mast cell stabiliser eg lodoxamide, nedocromil and sodium cromoglycate • Start their use ideally 1/12 before allergy season • Diclofenac is also licensed and steroids can be used only after examination on a slit lamp and seen by an ophthalmologist • Eye sx alone are best treated topically, however if a pt has other sx oral antihistamines are recommended Secondary Corneal Abrasion Corneal Foreign Body Herpes – Dendritic Ulcer Corneal Ulcer, with pus in AC Chlamydia • Serotypes D-K are genital • Serotypes A-C causes Trachoma – worlds leading cause of blindness • It attacks mucous membranes & inhibits host cell protein synthesis • Topical Rx tetracycline ointment QDS 6/52 • Systemic - Doxycycline, Tetracycline or Erythromycin Under surface of eye lid (sub tarsal plate) Chloramphenicol • Broad Spectrum Abx with least overall resistance • It is a bacteriostatic and inhibits bacterial syntheses by reversibly binding to ribosome's which disrupts peptide bond formation and protein synthesis • Acts on Gram +ve and –ve organisms • MUST be stored in the fridge • Bathe away discharge before use • Regime – 2 hourly in severe cases for 24 hours then QDS for 5 – 7 days. Side Effects/Cautions • Stinging, local discomfort • Greater chance of allergy than Fusidic acid • Aplastic anaemia (bone marrow suppression) check FHx and GH • Gray Baby syndrome • Avoid in pregnancy, breast feeding and with caution in under ones • Check bloods regularly if using long term • Not sensitive to Pseudomonas Fusidic Acid • Is a bacteriostatic and bactericidal agent with a steroidlike structure of no glucocorticoid activity. • Inhibits bacterial protein synthesis and prevents elongation of the peptide chain. • It is chemically unrelated to any other antibacterial in clinical use • There is no cross-resistance nor cross sensitivity between Fusidic acid and other antibacterials • It is microcrystalline giving it sustained release properties therefore concentration is maintained for 12 hours in lacrimal fluid and aqueous humour (BD dose regime) Side Effects/Cautions • Stinging, local discomfort, burning redness and watering on initial instillation • Allergic reactions are less than Chloramphenicol • Not known to be harmful in pregnancy • Is excreted in breast milk – not known to be harmful – weigh up risks/benefits. • Can be local variations of resistance Antibiotic efficacy against common ocular pathogens Pathogen * Known Activity Fusidic Acid Chloramphenicol Staph’ Aureus * * Staph’ epidermis * * Strep’ pyogenes Sensitive * Strep pneumoniae Sensitive * * * Escherichia coli Resistant * Haemophilus influenzae Sensitive * Pseudomonas Resistant Resistant Gonorrhoea OTC products for conjunctivitis • Brolene and Golden Eye are antiseptic not antibiotic • They are of little use • They commonly cause an allergic reaction which compounds the patients symptoms • They are used in acanthamoeba keratitis (organism grown on contact lenses) • Chloramphenicol is now OTC Advice to patients • Conjunctivitis is self limiting and will resolve without Rx in mild cases • Clean eyes with cooled boiled water • Avoid touching and rubbing eyes • Wash hands after touching eyes • Avoid sharing towels/face cloths • Throw away make up that may be contaminated • Contact Lenses SHOULD NOT be worn due episode and leave for 48hours after finishing Rx Contact Lenses • Types include soft, hard (gas permeable) disposable and extended wear. • Should not be worn during infections • Strict hygiene, cleaning and maintenance should be encouraged at all times • Soft CL are not compatible with drops that contain preservatives • Soft CL absorb Fluorescein and permanently stain Instilling eye medication • Drops contain preservatives to prevent micro-bacterial growth • 1/12 shelf life-throw out after • Clean discharge away first • Wash hands • Pull on lower eyelid to make a ‘well’ – drop solution or squeeze ointment into eye. • Avoid touching the tip of the bottle with the eye Anti-virals • Herpes Simplex and Zoster • Acyclovir (Zovirax) comes in tablet and oral form and used for both types of herpes. Ointment is used 5 x a day and compliance is essential to ensure disruption of the DNA synthesis. • Pt’s should be monitored by an ophthalmologist as corneal scarring will occur • Side effects from topical Rx include irritation, stinging, itching, inflammation, pain and photophobia Oral & Topical Steroids Overdose or prolonged use can exaggerate some of the normal physiological actions of corticosteroids leading to mineralocorticoid and glucocorticoid side effects • Adrenal suppression amongst many things can cause Conjunctivitis. • Suppression of infection therefore masks sx and exacerbates infections e.g. bacterial, viral and fungal • Causes – next slide Cataract Systemic steroids have a high risk (75%) of inducing a cataract Glaucoma Papilloedema Sclera Thinning Amiodarone • Used in Rx for arrhythmias • Has a very long half life extending to several weeks. • SE’s can cause reversible corneal deposits (causes night glare), Optic neuritis – causing blindness • Treatment MUST be stopped and expert advice taken Amiodarone Blurred Vision Optic Neuritis Corneal Deposits Antimalarials • Hydroxychloraquine and chloroquine are also used to treat Rheumatoid arthritis and SLE CAUSES Ocular Toxicity Retinal damage & Keratopathy (Corneal Deposits) Royal College of Ophthalmologists • Recommend regular ophthalmic examination • Arrangement should be made locally between prescriber and ophthalmologist and agreed management plan for those on long term treatment of 5 yrs or more. • Va - distance and near recorded before, during and after Rx • Any visual impairment needs to be assessed and recorded before, during and after Rx • Any deterioration in vision MUST be assessed by ophthalmologist • Children receiving treatment for Juvenile Arthritis should be screened for Uveitis TB Drugs Ethambutol is included in a Rx regime when there is resistance to other TB drugs • SE’s – Loss of VA • Colour Blindness • Reduction and restriction in Visual Field The dark patches show loss of vision • Side effects are more common when given in excessive doses • The drug should be stopped at the earliest presentation of ocular toxicity • Always advise pt’s to stop Rx and seek medical and ophthalmic help • Eye sight is nearly always restored if discontinuation of drug is early enough • Pt’s who may not understand warnings about visual sx should be given an alternative TB drug if possible • Children under 5 may not be able to report changes Visual Acuity should be tested before starting treatment Other Systemic Drugs • Tamoxifen – oestrogen antagonist Causes visual disturbances including corneal changes, cataracts and Retinopathy • Digoxin Toxicity – causes visual disturbance • MAOI’s (monoamine oxidase inhibitors) – causes blurred Va, Nystagmus and interacts with Sympathomimetics e.g. Phenylephrine (drug used to dilate pupil) Retinopathy Diagnostic Drops • Fluorescein – Orange die • Stains conjunctival and corneal epithelial damage e.g. corneal ulcers, erosions, and conjunctival or corneal abrasions • Assessment of dry eye • Tonometry • Fluorescein is available as drops or as paper strips • Fluorescein grows pseudomonas therefore is always used in single dose units • It is also used IV so photographs can be taken of retinal blood vessels, optic disc and macula Blood vessels Optic disc Scar Rose Bengal • Stains dead conjunctival and corneal epithelium in dry eye syndrome. • It causes pain and stinging on instillation Dead Corneal epithelium Dry Eyes 3 Layers of Tear Film Artificial Tears • Are used for dry eyes and must be used as often as possible to keep the eyes feeling comfortable. • Can be as often as every hour • Once diagnosed – drops will be necessary for life • Dry, hot, windy conditions exacerbate sx also reading, using PC (Starring for long periods) Types • Drops include – Hypromellose, Tears Naturelle, Liquifilm • Gel tears – ‘Viscotears’ – bind with own natural tears and stay in eye for longer • Ointments – used at night, stay in eye for longer, can cause blurring of vision. List 3 things you’ve learnt • 1 • 2 • 3 • Try and remember them!!!! Resources • http://www.goodhope.org.uk/departments/eyede pt/dropsfor.htm • http://www.bnf.org • Maclean H (2002) The Eye in Primary Care, Butterworth Heinmann. • Galbraith et al (1999) Fundamentals of Pharmacology, Addison Wesley Longman Ltd • Spalton et al (2006) Atlas of Clinical Ophthalmology 3rd Ed, Elsevier Mosby Any Questions