drugs Flashcards
ANTI-MUSCARINIC
(tropicamide, cyclopentolate, atropine)
acts on parasympathetic innervation of ciliary body + sphincter pupillary
blocks muscarinic receptor by preventing binding of acetylcholine
produces cycloplegia + mydriasis
SYMPATHOMIMETICS (phenylephrine)
acts on sympathetic innervation of dilator pupillae
stimulates sympathetic NS, acts on alpha-1 receptors + invokes response
parasympathetic NS neurotransmitter + receptor
major neurotransmitter - acetylcholine
acts on muscarinic receptor
sympathetic NS neurotransmitter + receptor
major neurotransmitter - noradrenaline
acts on alpha + beta receptors
MYDRIATICS RISKS
inducing ACG attack (1/5000)
blurred vision post instillation - TRO 4-6 hours until vision back to normal
glare - advise sunglasses
tropicamide indications
miosis (physiological, age, drug induced - pain meds)
H&S - flashes/floaters, sudden reduction in VA
specific px groups - >60, diabetic, cataract (esp. if referring), monitoring conditions e.g., naevus, drusen
tropicamide contraindications
hypersensitivity to tropicamide or any component of preparation
confirmed or suspected angle closure
multi-dose preparations contain benzalkonium chloride - should not be used when soft CLs worn (wait at least 15 mins before reinsertion)
tropicamide side effects
ocular - transient stinging + blurring, photophobia, raised IOPs
general - CNS disturbances, dry mouth
cyclopentolate refractive indications
under 16s
presenting strabismus in children
family hx squints
unequal/reduced VA in children
variable refraction
suspect latent hyperopes
cyclopentolate therapeutic indications
to break synechiae (when dilating anterior uveitis px)
reduce ciliary spasm (reduces pain if had trauma to eye e.g., corneal abrasion)
cyclopentolate side effects
ocular side effects - transient stinging + blurring, photophobia, raised IOP, conjunctival hyperaemia/ oedema
general side effects - CNS disturbances, dry mouth, flushing, tachycardia, urinary or GI symptoms
cyclo contraindications
hypersensitivity
confirmed or suspected angle closure
phenylephrine indications
when monotherapy is insufficient for mydriasis
differentiation between scleritis + episcleritis
phenylephrine contraindications
hypersensitivity to phenylephrine
px with cardiac disease, hypertension, aneurysms, asthma, long-standing insulin dependent diabetes, tachycardia
px taking tricyclic antidepressants + antihypertensive agents (beta blockers)
angle closure or narrow angles
phenylephrine side effects
ocular - transient stinging + blurring, photophobia, conjunctival allergic reaction, raised IOPs, punctate keratitis
general - tachycardia, palpitations, cardiac arrhythmias, hypertension, HAs
10% phenylephrine contraindicated age
contraindicated in children under 12 years and adults over 65 - increased risk of systemic toxicity
anaesthetic action
suppress action potentials in excitable tissues by blocking voltage-gated sodium channels which are involved in pain impulse transmission
local anaesthetic esters vs amide
esters - proxymetacaine 0.5%, oxybuprocaine 0.4%, tetracaine 0.5/1%
amide - lidocaine 4% with 0.25% fluorescein
LIDOCAINE indication, contraindication, side effects
used for measuring IOPs by Goldmann
contraindication - hypersensitivity
ocular side effects - transient stinging + blurring, punctate keratitis (no general)
ESTER LOCAL ANAESTHETIC indications, contraindications, side effects
used for short-term procedures (Goldmann, gonioscopy, minor surgery, FB removal, aid ocular exam if px in severe pain)
C/Is - hypersensitivity to ester type anaesthetics, pre-term neonates
side effects - transient stinging + blurring, punctate keratitis, hyperaemia
ocular anaesthesia indications
Goldmann/ perkins
gonioscopy
minor surgery
FB removal
blepharospasm - aid ocular exam if px in severe pain
RGP fitting
Schirmer test
ADVICE AFTER LOCAL ANAESTHETIC INSTILLATION
re-examine eye after use (check for reaction)
provide note with drug + ADR advice
do not rub eyes (30 mins after)
do not use CLs for 30 mins after
LOCAL ANAESTHETIC ADVERSE REACTIONS
delayed healing + tear flow
lower IOP
light headedness
tinnitus
