Pharmacology Flashcards
How are drugs administered to the eye
Topically As drops or ointment Subconjunctival Subtenons (under fibrous layer below conjunctiva) Intravitreal Intracameral
What are the pros and cons to the two types of eye treatment
Ointments
- last longer so give better relief
- often blur the vision
Drops
- thinner and easier to administer
- Not as many visual effects - need to be given more frequently
Which part of the eye can lipid soluble drugs penetrate
The epithelium
It is lipophilic/hydrophobic
Limits the absorption of hydrophilic drugs
Which part of the eye can water soluble drugs penetrate
The stroma
It is hydrophilic/lipophobic
Limits the absorption of hydrophobic drugs
Name a drug that has both lipophilic and hydrophilic properties
Chloramphenicol
Can penetrate the cornea easily
What can make topical steroids more hydrophobic
Alcohol or acetate
What can make topical steroids more hydrophilic
Phosphate
Describe the use of prednisolone acetate
Topical steroid
Hydrophobic - due to acetate
Good penetration of an uninflamed cornea
Used post-operatively
Describe the use of prednisolone phosphate
Hydrophilic - due to phosphate
Poor penetration of uninflamed cornea
Used for cornea disease, surface inflammation or when want low dose steroids
What is Bezalkonium
Surfactant and antibacterial agent
Common in household cleaners
Used as a preservative is eye drops
It aids penetration of drugs by disrupting lipid layer of tear film
How can you prevent the systemic absorption of topical eye drugs
Punctal occlusion
After administration, press on the tear ducts for around 5 mins
This stops the drug flowing down the lacrimal system and entering the throat (this would be the site of systemic absorption)
What is bimatoprost
Drug used to lower IOP in glaucoma
contains benzalkonium
What are the subconjunctival and subtenons routes of administration used for
Putting drugs in the back of the eye
In subtenons you place a small catheter around the eye under the tenons layer
Used for anaesthetics and steroids
What is a major risk of injecting into the back of the eye
If the retina is punctured by the needle it can lead to a retinal detachment
What are steroids used for in eye disease
Topically given in post-op cataracts
Uveitis
Prevention of corneal graft rejection
May be given in allergic eye disease (if other drugs haven’t worked)
What is one of the first signs of corneal graft rejection
New vascularisation of the cornea
Vision will go hazy
What are keratic precipitants in the eye
White dots in the eye which are deposits of white cells
What are the local side effects of steroids in the eye
Cataracts
Glaucoma
Exacerbation of viral infection - such as herpes simplex
Impaired wound healing
What are the systemic effects of steroids
Gastric ulceration Immunosuppression Osteoporosis Weight gain AND many more
What anti-inflammatory agents can be used in eye disease
Steroids
Antihistamines and mast cell stabilisers (sodium chromoglycate) for allergic disease
NSAIDs are good for pain relief
Why might people not notice the vision loss in glaucoma
Slowly progressing
The brain compensates the missing parts of the image by filling it in with what it expects to be there
List drugs that can be used in the treatment of glaucoma
Prostanoids - prostaglandin analogues
Beta blockers
Carbonic anhydrase inhibitors - topical and systemic
Alpha adrenergic agonists - sympathomimetics
Parasympathomimetic drugs
Give an example of a prostanoid/prostaglandin analogue and explain how it helps treat glaucoma
Latanoprost
They increase uveoscleral outflow - open up the drains to reduce pressure
Give an example of a beta blocker and explain how it helps treat glaucoma
Timolol
Reduces secretion of aqueous humour
Give an example of a carbonic anhydrase inhibitor and explain how it helps treat glaucoma
Dorzolamide, other -mides and Trusopt
Reduces production of aqueous humour by blocking one of the enzymes in its production pathway
Give an example of an alpha adrenergic agonist/ sympathomimetic and explain how it helps treat glaucoma
Brimonidine and alphagan
Dilates pupil
Reduces production of humour
Increases uveoscleral outflow
Give an example of a parasympathomimetic and explain how it helps treat glaucoma
Pilocarpine
Constricts the pupil to help open up the trabecular meshwork = drain
Describe how the intravitreal route is used in eye medication administration
Delivers effective concentration of drug at target site instantly
Used for antibiotics for endophthalmitis, intra-ocular steroids and anti-VEGF
However many drugs are toxic to the retina
What is anti-VEGF treatment used for
Shrinking newly formed blood vessels
Useful in wet macular degeneration, diabetic maculopathy etc.
What is local anaesthetic used for in ophthalmology
Removal of foreign bodies Tonometry Corneal abrasions - pain relief and allows examination Corneal scraping Comfort Cataract surgery
How is fluorescein used
Dye that is placed in the eye and then a blue light is shone on it to illuminate de-epithelialised areas
Will show corneal abrasions, ulcers, leaks (suggestive of injury)
Can be used to diagnose duct obstruction
What is the effect of mydriatic drugs
They cause pupil dilation by blocking parasympathetic supply to the iris
Give examples of mydriatics
Tropicamide - most common but short acting
Cyclopentolate - lasts a whole day
Atropine - lasts up to 3 weeks
What are the potential side effects of mydriatics
Blurring
Acute angle closure glaucoma
How do Sympathomimetics work
Act on the sympathetic system to dilate the pupil
What drug must never be given to someone with herpetic keratitis
Steroids
Will cause a corneal melt
How do eye drop allergies present
usually symmetrical reaction around both eyes
redness and swelling
Steroids can cause cataracts - true or false
True
Even inhaled ones increase your risk
Why are mydriatic/dilating drugs used in ophthalmology
Used for diagnostic procedures - easier to visualize back of eye
Used to gain access in cataract surgery
Cyclopentolate can be used to reduce pain from cilliary muscle spasm as it paralyses this muscle
How are eye drops written in a prescription
G….drug name
How are eye ointments written in a prescription
Oc… drug name
List examples of topical antibiotics used in the eye
Most common is chloramphenicol
Ulcers cab be treated with gentamicin or quinolones as well
List examples of topical antivirals used in the eye
Aciclovir
Ganciclovir
Local anaethetic drops can be very toxic to the epithelium of the eye - true or false
True
What is Seidel’s test
A test used to show leaks from the cornea, sclera, or conjunctiva following injury or surgery.
You add fluroscein to the eye and if there is a leak the aqueous fluid coming through will dilute it and cause a colour change - Seidel positive
List side effects of prostanoids
Hyperpigmentation of iris, lashes and/or skin
List side effects of carbonic anhydrase inhibitors
For the systemic ones:
Parasthesia in the fingers, toes and/or lips
Renal calculi
Metabolic acidosis
Topical ones can cause local irritation
List side effects of beta-blockers
Systemic side effect - reduced by shutting eyes for a few minutes
Bradycardia
Fatigue
Contra-indicated in asthma and COPD
List side effects of sympathomimetics
Allergy Lethargy/drowsiness local irritation, hyperaemia cardiovascular side effects Contraindicated in kids – restricts their breathing
List side effects of parasympomimetics
Brow ache during first few weeks of use
Poor vision in low light
Due to persistent constriction of pupil
