Week 2.01 Adverse Reactions Flashcards
(60 cards)
What is mean by an adverse effect
Side effect: undesired effect of medication extraneous to the intended therapy
Adverse effect: negative side effect
If you have a rich blood supply and small mass of the eye are you more or less likely to have advserve effects
More likely
In the cornea what may the drugs bind to
In cornea – drugs may bond in the stroma to glycosaminoglycans which could result in swelling and decrease in transparency
What are the two ways drugs can enter the eye and leave the eye
When drugs enter eye via uveal circulation they exit eye via canal of schlemm or ciliary body
Drugs entering via retinal circulation may leave the eye by systemic circulation or diffuse into vitreous
What is the WHO scale
1) Certain – is a definite relationship between the time drug taken and which effects occurred/ cannot be explained by any other disease present
2) Probable/likely
3) Possible
4) Unlikely
5) Conditional/unclassified
6) Un-assessable/unclassifiable
What might you see in a px eye if u suspect drug adverse effects
- deposition of pigmentation on the eyelids or conjunctiva or changing transparency of the cornea or lens
- Deposits on px retina
- Drugs might affect ANS - changes to size of pupil, inhibit accommodation, deviation in position of eyes or eyelids (extraocular muscles/eyelids)
- visual hallucinations
- notice a change in VA, constriction of visual field, strange colour vision effects
- vascular effects - leakage or occlusion
Aye and adverse reactions
- Older px more likely to be taking systemic medications
- Polypharmacy – taking 4 or more medications
- Blood-retina barrier becomes less effective with age – usually the retinal vascular endothelium and retinal pigment epithelium blocks the drug molecules entering
- Reduced ocular perfusion pressure – a value calculated by taking 2/3rds of the mean arterial blood pressure and subtracting from that the interocular pressure and it gives an indication of ocular blood flow
- If this reduces then a sign that blood flow has reduced and eye more susceptible to ocular disease
What is ED50
Median therapeutic dose of a drug
Narrow therapeutic index
Drugs with a narrow therapeutic index are more likely to cause an adverse reaction
Narrow therapeutic index: when toxicity occurs at less than twice the ED50
What is the TD50 value
TD 50 value which is the dose of the drug which produces toxicity (e.g. unwanted side effects) again in 50% of individuals who have been given that specific dose
What does large therapeutic index tell us
Large therapeutic index means u would have to have a significant increase in dose, way above therapeutic levels to see any toxic effects
Need to consider drugs that may affect:
- cornea
- occulomotor system - eye movements, accommodation
- tear film
- intraocular pressure
- lens
- retina
- visual field
- colour vision effects
What are drugs that affect the cornea
- amiodarone
- chlorpromazine (Thorazine) - antipsychotic
What is amiadarone, side effects, progression
Drug that affects cornea
- used to treat cardiac arrhythmia- irregular heartbeat
- works by prolonging reploarisation in heart
- main ocular side effect is appearance of corneal micro deposits - corneal verticillata
Px taking 400 - 1000mg daily will probably develop keratopathy
- dose dependent
Therapy duration dependent
What are the 3 stages to development and progression of amiodarone keratopathy
Amiodarone keratopathy
Corneal deposits seen 6 days after
Increasing severity
Lower doses typically stage 1
Stage 3 more higher dose px
Bilateral
Px wont notice change in vision minority may notice halos
Stage 1: fine grey deposits on inferior cornea, linear pattern
Stage 2: additional horizontal lines, plus arborising (tree like branching deposits
Stage 3: verticillate “whorl-like” pattern
Do not fade away if stopped. Don’t usually stop this medication as heart more important than corneal deposits
What are the other ocular effects of amiodarone
Lens opacities
Retinal and optic nerve deposits
Optic neuropathy
What is amiodarone optic neuropathy
More serious
Occurs in 2% prescribed this med and more common in men
Swelling of disc - borders appears less distinct
Can lead to bilateral vision loss
Occur within first 12 months
What is chlorpromazine and what are the side effects
Antipsychotic medication - affects px cornea and lens
- treats schizophrenia
- can cause skin and ocular pigmentation at high doses over long period of time
- pigmentary deposits in descemets membrane and endothelium white, brown, black
- Changes are dose dependent
- IRREVERSIBLE changes - deposits
- may be see on surface of lens
Px can have a chlorpromazine stellate cataract - looks like a star shape
What are the drugs that affect anterior angle
- topiramate - aka topamax
What is topiramate and what are the side effects
Affects anterior angle
• Antiepileptic drug
• Has also been used for: migraine prophylaxis, trigeminal neuralgia, bipolar disorder, idiopathic intracranial hypertension
• Used in adults and children >2yrs
Side effects:
• Acute onset angle closure glaucoma – ciliary body oedema pushes iris forward blocking drainage
• Acute myopia
• Peri-orbital oedema
• Scleritis
• Blepharospasm
• Nystagmus
• Diplopia
Maj females age 34 who suffered glac attack, range of refractive errors, link with px prescribed SSRIs
Look out for headaches, blurred vision, vomiting
What drugs affect oculomotor
- tricyclic antidepressants - amitriptyline hydrochloride
- motion sickness drugs - hycosine, scopolamine
- over counter cough and cold - contains sympathomimetic phenylephrine
- thyroid hormone replacements - levothyroxine
- heroin - methadone
What’s are tricyclic antidepressants and what are the side effects
• Tricyclics exert antimuscarinic effect – therefore will have a cycloplegic and a mydriatic action
• Risk of closed angle glaucoma in “at risk” individuals
• Px may complain of blurred vision and photophobia
• May need near add, tinted spectacles
• Dry mouth, blurry vision, increased body temp
Effects are transient and reversible – so if stop med side effects will reduce
What are motion sickness drugs and what are the side effects
Hyoscine, scopolamine
- scopoderm - patch applied to skin behind ear
- help treat motion sickness or travel sickness
- exerts an antimuscarinic effect - therefore will have a cycloplegic and a mydriatic action
Side effects
- blurred vision and photophobia
- reversible when stop drug
What are over counter cough and cold and what are side effects
- contains sympathomimetic phenyelphrine
Side effects:
- dilation of the pupils
- photophobia
- risk of ACG
- reduces conjunctiva hyperaemia as blood vessels constricted however could then be masking an imp anterior eye sign