Medical Management of Glaucoma Flashcards
B adrenergic antagonist and prostaglandin analogue
- B adrenergic antagonist = was commonly used
- prostaglandin analogue = now is first line of treatment for glauc therapy as it has a sim pressure lowering effect to beta blockers but has a safety profile
target IOP
= upper limit of the IOP estimated to be compatible with a rate of progression suffciently slow to maintain vision related quality of life for the expected lifetime of the px
- no single target IOP that is appropriate for every px and needs to be determined individually
- all drugs licensed to treat glaucoma are licensed as IOP lowering agents
- IOP lowered by 20-35% (approx 5-7mmHg on avg)
LiGHT trial
- Lancet published a study earlier this year on the LiGHT trial, a multicentred double masked RCT comparing selective laser trabeculopasty (SLT) to eye drops for treat pxs with open angle glaucoma, which found SLT provided more robust IOP lowering while being a more cost efficient first line treatment
- SLT could be offered as a first line treatment for open angle glaucoma and ocular htn
classes of drugs (topical)
- prostoglandin agonists
- beta receptor antagonists
- alpha 2 receptor agonists
- carbonic anhydrase inhibitors
- cholinergic receptors
mechanism of action: topical drugs
- reduce aqueous production (CAI’s, a receptor agonists, and b receptor antagonists)
- increase outflow through the trab meshwork (cholinergics)
- increase uveoscleral flow (PGA, prostamide, brimonidine)
classses of drugs (systemic)
- tend to be used in px with acute angle closure
- carbonic anhydrase inhibitors eg acetzolamide (diamox)
- osmotic agents eg glycerol, mannitol
what to do before prescribing any new drop for glaucoma
- general medical history
- drug history
- history of topical allergy
- find out if the px can use eye drops (memory and dexterity, carers)
what to look for when choosing a drug
- efficacy
- safety
- compliance
- cost
order of efficacy of topical drugs
1) prostaglandin agonists 25-35%
2) beta antagonists 20-30%
3) alpha 2 agonists 18-25%
4) cholinergic agonists 20-25%
5) carbonic anhydrase inhibitors 20% - rarely used in first line, tend to be used in conjunction
which PGA to use
prostaglandin analogues:
1) Latanoprost (non proprietary and xalatan) - dose 50micrograms/ml
2) Travoprost (travatan) - dose 40 micrograms/ml
3) Tafluprost (saflutan) - dose 15 micrograms/ml - unit dose
prostamide
- bimatoprost (lumigan) - 100micrograms/ml - acts on uvoscleral pathway so similar mode of action to PGAs
PGA: side effects
- darkening, thickening and lengthening of the eyelashes
- increased iris pigmentation - doesnt tend to affect blue/green eyes
beta antagonists
1) Timolol maleate (non proprietary and timoptol 0,5% and tiopex 1mg/g)
2) Betaxolol (betoptic) 0.25% - available as unit dose
3) Levobunolol HCl (betagan) 0.5% - available as unit dose
timolol = non selective - binds to b1 and b2 receptors betaxolol = selective - B1 receptor blocker, avoids bronchoconstriction
fixed combinations of beta antagonists
- latanoprost with timolol (non proprietary)
- bimatoprost with timolol (ganfort)
- brimonidine with timolol (combigan)
- dorzolamide with timolol (corsopt)
beta antagonists side effects
- glacoma and airway disease frequently co exist
- glauc affects 5% of people over 65
- airways obstruction affects 40% of people over 75
- main side of beta blockers is they can cause bronchoconstriction esp in pxs with obstructive airways disease or asthma - lungs have b2 receptors and stimulating/ blocking these receptors causes bronchoconstriction
unrecognised respiratory impairment by topical b antagonists
- timolol may impair respiratory function and exercise tolerance of elderly pxs even if they have no history of reversible airways disease
if prescribing b antagonists
- ask about COAD/SOBOE (shortness of breath of exertion)/ inhalers
- check peak flow
- check pulse
- consider drug interaction
- recheck peak flow one month after starting treatment - stop if fall of 15%
alpha agonists
1) brimonidine tartrate (non proprietary and alphagan) 0.2% - reduces aq secretion and increases uvoscleral outflow
2) apraclonidine HCl (iopidine) 5mg/ml - often used in pre and post operative setting as it is an effective short term lowering agent
alpha agonists side effects
- a2 agonists have a high incidence of ocular and systemic side effects
- ocular side effects include folliclar conj
- systemic side effects include hypotension, syncope, dry mouth and nose, headache, anxiety, depression and fatigue
carbonic anhydrase inhibitors
1) dorzolamide Hcl (non proprietary and Trusopt which is available as unit dose) 2%
2) brinzolamide Hcl (non proprietary and Azopt) 10mg/ml
- dorzolamide / brinzolamide are both available as a fixed combination with 0.5% timolol and brinzolamide in a fixed combo with brimonidine (simbrinza)
- the oral carbonic anhydrase inhibitor acetazolamide mainly use in the treatment of acute angle closure
topical CAI side effectors
- mettalic taste
- rashes
- polyuria
- irritation
- blurred vision
oral CAI side effects
- allergy
- hypokalemia - low level of potassium, can cause cramps, weakness, constipaiton
- polyuria
- acidosis
- depression
- paresthesia
- kidney stones
- blood dyscrasia
cholinergic agonists
1) pilocarpine HCl non proprietary, dose 1%, 2% and 4%
2) pilocarpine nitrate minims 2%
- rarely prescribed
side effects of cholinergic agonists
- miosis
- myopia
- symblepharon - adhesion of palpebral and bulbar conjunctiva
- post synechiae
- ret detachment
- confusion
- vomitting
- nausea
compliance and issues
- simplicity of treatment regime
- memory
- manual dexterity
- understanding of disease
- topical and systemic side effects
- all eye drops sting - for most people this is the only symptom of their glauc
