Ocular Pharmacology Flashcards
True or false: physiological barriers prevent the penetration of systemically-administered drugs into the eye at therapeutic concentrations.
True.
Although, in an inflamed eye, drug penetration may be greater.
Name the properties of a topical drug which permits penetration of corneal epithelium and stroma into the anterior chamber.
A molecule with hydro- and lipophilic properties gives best absorption.
Fat-soluble drugs readily cross the corneal epithelium but not the corneal stroma. Water-soluble drugs cannot penetrate the corneal epithelium but can cross the stroma.
The endothelium presents only a minor barrier.
Which two properties favour ocular absorption of systemically administered drug?i
High lipid solubility and low molecular weight.
Give two examples of eye disease where topical treatment may be supplemented by subconjunctival injection.
- Acute anterior uveitis
2. Bacterial keratitis
True or false: the treatment of intraocular bacterial infection does not frequently involve the injection of ABx directly into the globe.
False; it does frequently involve direct injection into the globe.
True or false: the risk of ocular side effects from drugs administered systemically (for non-ocular disease) is rarely great and is usually outweighed by clinical therapeutic necessity.
True.
What are the adverse effects of amiodarone on the eye?
Corneal deposits (vortex keratopathy) - Tom had these with his AF Rx
What are the adverse effects of antiepileptics on the eye?
Ocular motility dysfunction
What are the adverse effects of benzhecol, benztropine and atropine on the eye?
Pupillary dilatation (risk of angle closure glaucoma)
What are two adverse effects of systemically-administered corticosteroids on the eye?
- Cataract
2. Glaucoma
What are the adverse effects of digitalis on the eye?
Abnormal colour vision
What are the adverse effects of ethambutol and quinine on the eye?
Optic neuropathy
What are two adverse effects of hydroxychloroquine and chloroquine on the eye?
- Retinal degenerative change (“bull’s eye macula)
2. Corneal deposits
What are the adverse effects of opiates on the eye?
Pupillary constriction
What are three adverse effects of phenothiazines on the eye?
- Retinal oedema
- Pigmentary retinopathy
- Ocular motility dysfunction
What are the adverse effects of sulphonamides and NSAIDs on the eye?
Stevens-Johnson syndrome
What are the adverse effects of tamoxifen on the eye?
Pigmentary neuropathy
What are 5 types of drugs used in glaucoma treatment (where different types of glaucoma require different therapeutic approaches)?
- Beta blockers (timolol, carteolol, betaxolol, levobunolol)
- Muscarinic (parasympathetic) stimulants (pilocarpine)
- Alpha-2 stimulants (brimonidine, apraclonidine)
- Latanoprost
- Carbonic anhydrase inhibitors (systemic = acetazolamide; topical = dorzolamide).
*all are topical except where indicated
How do beta blockers work to treat glaucoma?
Reduce aqueous secretion by inhibitory action on beta-adrenoreceptors in the ciliary body.
How do muscarinic (parasympathetic) stimulants/agonists work to treat glaucoma?
Increase aqueous outflow via trabecular meshwork by ciliary muscle contraction.
How do alpha-2 stimulants/agonists work to treat glaucoma?
Reduce aqueous secretion by selective stimulation of alpha-2 adrenoceptors in the ciliary body and increase outflow vis uveoscleral route.
How does latanoprost work to treat glaucoma?
A prostaglandin analogue; increases aqueous outflow by uveoscleral route.
How do carbonic anhydrase inhibitors work to treat glaucoma?
Reduce aqueous secretion by the ciliary body.
In treating glaucoma with beta blockers, what are some of the ocular and systemic side effects of this drug?
Ocular: irritation
Systemic: bronchospasm, bradycardia, exacerbation of heart failure, nightmares.
In treating glaucoma with muscarinic (parasympathetic) stimulants, what are some of the ocular and systemic side effects of this drug?
Ocular: miosis (reduced vision in presence of cataract, retinal examination impaired); spasm of accommodation, brow ache.
Systemic: sweating, bradycardia, gastro-intestinal disturbance.
In treating glaucoma with alpha-2 stimulants, what are some of the ocular and systemic side effects of this drug?
Ocular: allergy, mydriasis, eyelid retraction.
Systemic: dry mouth, hypotension, drowsiness, headache.
In treating glaucoma with latanoprost, what are some of the ocular and systemic side effects of this drug?
Ocular: iris colour change, conjunctival hyperaemia
Systemic: bitter taste
In treating glaucoma with carbonic anhydrase inhibitors, what are some of the ocular and systemic side effects of this drug?
Ocular (topical drug): irritation, allergy.
Systemic (& generally with systemic version of drug): malaise, paraesthesia, urea and electrolyte disturbance, aplastic anaemia.
Name two types of drugs which act as mydriatics and cycloplegics [for retinal examination and objective refraction (retinoscopy)].
- Antimuscarinics (tropicamide, cyclopentolate, atropine).
- Alpha-stimulant (phenylephrine)
*all topically applied
By what mechanism do antimuscarinics work as a mydriatic/cycloplegic to enable retinal examination and objective refraction (retinoscopy)?
Anti-muscarinics inhibit muscarinic receptors of parasympathetic nervous system to paralyse pupillary sphincter and ciliary muscle.
By what mechanism do alpha-agonists work as a mydriatic/cycloplegic to enable retinal examination and objective refraction (retinoscopy)?
Alpha agonists work as a mydriatic to stimulate dilator muscle of the pupil; no cycloplegic affect.
What are some of the ocular and systemic effects of antimuscarinics, which act as mydriatics and cycloplegics for retinal examination and objective refraction (retinoscopy)?
Ocular: blurred vision (especially for near), glare, angle closure glaucoma.
Systemic: tachycardia, dry mouth, confusion, tremor.
What are some of the ocular and systemic effects of alpha-stimulants, which act as a mydriatics for retinal examination and objective refraction (retinoscopy)?
Ocular: blurred vision, glare, angle closure glaucoma.
Systemic: hypertension.
Name 4 types of lubricants which can be used for the treatment of dry eye?
- Carbomers
- Hypromellose
- Polyvinyl alcohol
- Liquid paraffin
*all topical; exact mechanism depends on agent.
Name some of the ocular and systemic side effects of eye lubricating agents?
Ocular: preservative allergy/toxicity, blurred vision (especially ointments).
Systemic: nil.
Name 5 categories of anti-inflammatory agents used for treating ocular disease.
- Corticosteroids (prednisolone, betamethasone, dexamethaxone)
* corticosteroids most important - Systemic immunosuppressants
- Topical mast cell stabilisers (cromoglycate, nedocromil, alomide)
- Antihistamines (topical = levocabastine; systemic = chlorpheniramine, terfenadine, cetirizine).
- NSAIDs (systemic = help to control ocular pain and inflammation; topical = increasingly used for pain of corneal abrasion, for inflammation after cataract surgery, and to maintain pupil dilation during cataract surgery).
By which three methods can corticosteroids be administered to treat eye disease?
Topical, periocular injection, systemic.
How do corticosteroids act to treat eye disease?
Suppression of a broad spectrum of inflammatory processes.
Name some of the ocular and systemic side effects of corticosteroids.
Ocular: glaucoma (especially with local administration), cataract (especially prolonged systemic use), exacerbation of some infections (eg. herpes simplex).
Systemic: negligible with topical use; common and varied with systemic administration.
Name some ocular and systemic side effects of topical mast cell stabilisers.
Ocular: irritation.
Systemic: nil.
By which mechanism do NSAIDs work?
They modulate prostaglandin production.
Name some ocular and systemic side effects of topical and systemic NSAIDs.
Ocular (topical): nil
Systemic (systemic): peptic ulcerstion, asthma.
Name 5 commonly used antibacterials in ophthalmology.
- Chloramphenicol
- Gentamicin
- Ciprofloxacin
- Neomycin
- Fusidic acid
Topically applied antibacterial and antiviral agents are very commonly prescribed; the use of antifungal and antiparasitic agents is much less frequent.
Name three methods by which antibacterials can be administered to treat eye disease.
- Topical
- Intra-ocular (occasional)
- Systemic
Name some ocular and systemic side effects arising from antibacterial treatment of eye disease.
Vary with agent.
Ocular: allergy, corneal toxicity common with intensive use.
Systemic: generally only with systemic use.
Name one common antiviral used in ophthalmology.
Acyclovir.
Inhibits herpes virus DNA synthesis.
Name three methods by which acyclovir can be given in ophthalmology?
- Topical
- Systemic
- Intravitreal
Name some ocular and systemic side effects of acyclovir.
Ocular: blurred vision, corneal toxicity.
Systemic: rashes, kidney, liver and other effects may occur with systemic use.
Name three local anaesthetics commonly used in ophthalmology.
- Oxybuprocaine
- Amethocaine
- Lignocaine
Major uses are to relieve pain and thereby assist with clinical examination, and the facilitation of surgical anaesthesia. They block conduction along nerve fibres.
Name two methods by which local anaesthetics can be administered in ophthalmology.
- Topical
2. Periocular injection
Name some ocular and systemic side effects associated with local anaesthetics in ophthalmology.
Ocular: irritation, corneal toxicity.
Systemic: generally accidental intravascular or intrathecal injection during surgical anaesthesia; cardiac arrhythmias; respiratory depression.
Name a compound/drug which is used for management of certain ocular motility disorders, blepharospasm, and to induce ptosis for corneal protection.
Botulinum toxin.
Always injected into the site of action.
What are three indications for the use of botulinum toxin in ophthalmology?
- Management of certain ocular motility disorders
- Blepharospasm
- To induce ptosis for corneal protection.
What is the mechanism of action of botulinum toxin, as well as side effects?
Prevents release of the neurotransmitter acetylcholine at neuromuscular junctions.
Side effects depend on the treatment site (eg. unwanted ptosis or double vision).
