Drugs used in Glaucoma Flashcards
What muscle constricts the pupil to cause miosis through activation of M3 receptors (GPCR coupled to Gq protein)
Iris circular muscle
What muscle dilates the pupil to cause mydriasis through activation of alpha1 adrenergic receptors (GPCR coupled to Gq protein) ?
Iris radial muscle
What Muscle causes accommodation of the eye to near vision through M3 receptor mediated contraction?
Ciliary muscle
What muscle opens trabecular meshwork, improves aqueous humor outflow in the canal of scheme and decreased IOP?
Ciliary m.
What produces aqueous humor?
Ciliary epithelium
What receptor activation increases humor production from ciliary epithelium?
Beta adrenergic
What receptor activation decreases humor production?
alpha2 adrenergic
Beta and alpha2 receptors activate what system?
sympathetic
What transports sodium and bicarbonate ions from the ciliary body to aqueous humor?
carbonic anhydrase
What increases transport of H2O to increase volume of aqueous humor?
carbonic anhydrase
What is the role of muscarinic receptors in aqueous humor outflow?
- contract ciliary M to improve outflow
- contract iris of circular muscle to cause miosis and improve outflow of aqueous humor to regulate IOP
What does Prostaglandin F2a do?
improves uveoscleral or unconventional outflow of aqueous humor to regulate IOP
What is the role of sympathetics in aqueous humor outflow?
Contract iris radial muscle (a1 receptor) causing mydriasis decreased outflow
-relax ciliary m via presynaptic a2 receptors to increase uveoscleral outflow
What is open angle glaucoma?
primary glaucoma that is chronic progressive disease with no apparent mechanical humor blockage
What is closed angle glaucoma?
primary glaucoma that is acute intermittent partial or completee blockage of outflow
- may have to be treated as an emergency to avoid vision loss
What is secondary glaucoma?
Glaucoma caused by other diseases, trauma surgery, or drugs
What drug classes reduce aqueous humor production to treat open angle glaucoma?
- Beta blocking drugs
- A2 adrenergic agonists
- Carbonic anhydrase inhibitors
What drugs increase aqueous humor outflow to treat open angle glaucoma?
- Prostaglanic analogs
- A2 adrenergic agonists
- direct cholinergic agonists
- inhibitors of cholinesterase
What is Betaxolol MOA?
reduces the production of aqueous humor by the ciliary body through blocking Beta receptors
What is timolol MOA?
reduces the production of aqueous humor by the ciliary body through blocking Beta receptors
What is metipranolol Moa?
reduces the production of aqueous humor by the ciliary body through blocking Beta receptors
What is Levobunolol MOA?
reduces the production of aqueous humor by the ciliary body through blocking Beta receptors
What is Carteolol MOA?
reduces the production of aqueous humor by the ciliary body through blocking Beta receptors
What beta blocker lacks local anesthetic effects, is available as generic, and a full antagonist?
Timolol–> is favored for these reasons as opposed to propranolol which possesses local anestethic effects and is not suitable for use in glaucoma
What drugs can have negative inotropic effects, Bradycardia, bronchospasm, hyperlipidemia, exacerbate hypoglycemia, increase risk of cardiac depression and heart block , ocular irritation dry eyes?
Beta blocker
Brimonidine MOA?
a2 agonist
- decrease rate of aqueous humor production
- increased uveoscleral outflow (esp. brimonidine) by relaxing the ciliary M.
Apraclonidine MOA?
a2 agonist
decrease rate of aqueous humor production
- increased uveoscleral outflow (esp. brimonidine) by relaxing the ciliary M.
What a2 agonist can develop tachyphylaxis and allergic rxns?
Apraclonidine
What are adverse effects of a2 agonists brimonidine and apraclonidine?
Headache
fatigue
dry mouth
allergic rxns (eyelid edema, itching, hyperemia
Topical: Brinzolamide and Dorzolamide
Systemic: Acetazolamide, Methazolamide
have what MOA?
- Carbonic anhydrase inhibitors
- decrease osmotic pressure of aqueous humor
What drugs have systemic adverse effects of
- nausea, diarrhea, loss of appetite, altered taste
- weightloss
- paresthesias
- renal stones
- decreased libido
systemic anhydrase inhibitors: acetazolamide and methazolamide
local carbonic anhydrase inhibitors( Brinzolamide and Dorzolamide) can cause irritation and redness
What is MOA of prostaglandin analogs?
reduce IOP by increasing uveoscleral and, lesser extent, outflow of aqueous humor
What is Latanoprost?
prostaglandin analog
what is bimatoprost?
prostaglandin analog - most effective in lowering IOP
what is travoprost?
prostaglandin analog
Are prostaglandin analogs or beta blockers better to reduce IOP?
Prostaglandin analogs more efficiently reduce IOP
Corneal erosions, conjunctival hyperemia, iris hyperpigmentation, hypertrichosis, and hyperpigmentation around the eyelashes and eyelids are local side effects of what?
Prostaglandin analogs (latanoprost, bimatoprost, travoprost)
What is the MOA of pilocarpine, carbachol and echothiophate?
cholinergic agonists, activated M 3 receptor directly or indirectly –> M3 receptor activation increases conventional humor outflow
Direct: Carbachol and pilocarpine
Indirect: echothiphate
What drug class can cause -headaches -miosis -eyelid twitching -myopia -cataracts iris- lens adhesions
Cholinergic agonists : pilocarpine, carbachol, echothiophate
How is open angle glaucoma treated?
- beta blocker or prostaglandin agent
2. if contraindicated, use brimonidine or topical anhydrase inhibitors
How is closed angle glaucoma treated for rapid reduction of IOP?
surgery prep: oral glycerin and IV mannitol
pilocarpine before surgery induces miosis
What agents reduce humor production in closed angle glaucoma?
- beta blockers
- a2 agonists
- carbonic anhydrase inhibitors
What promotes increase of IOP in open angle glaucoma?
- glucocorticoids (topical, systemic, inhaled)
- topical muscarinic drugs
What can trigger angle closure in patients with closed angle glaucoma?
drugs with alpha 1 adrenomimetic activity
antimuscarinc drugs (including tricyclic antidepressants
** can be triggered by any drug that causes mydriasis
