Ophthalmic Drugs Flashcards
What are the receptors of the Iris Sphincter?
- Muscarinic
2. Few Alpha and Beta
What are the receptors of the Ciliary Muscle?
- Muscarinic
2. Some Beta 1
What are the receptors of the Iris Dilator?
- Mostly Alpha 1
2. Few Beta
What are the receptors of the Ciliary Process?
- Mostly Beta 2
- Some Alpha 2 and Beta 1
- Muscarinic
What are the receptors of Mueller’s Muscle?
- Alpha 1
Which ocular muscles are mainly parasympathetic?
- Iris Sphincter
2. Ciliary Muscle
Which ocular muscles are mainly sympathetic?
- Iris Dilator
- Ciliary Process
- Mueller Muscle
What are 3 functions of Adrenergic Agonists for the eye?
- Mydriasis
- Treatment of Glaucoma
- Decongestant
What is Epinephrine?
An Alpha 1,2 and Beta 1,2 Adrenergic Agonist
What are the ocular uses of Epinephrine?
- Vasoconstriction
2. Glaucoma (not much anymore)
How does Epinephrine work to treat Glaucoma?
Alpha 1 and Beta 2 –> Increased Aq Production, but Beta 2 also increases Aq Outflow –> Decreased IOP
What are the side effects of Epinephrine?
- HA
- Hyperglycemia
- Tachycardia
- HTN
- Thyrotoxicosis
What are the ocular side effects of Epinephrine?
- Dilation
- Lid Retraction
- Lacrimation
- Pigmentation of the Iris/Lens (w/ Oxidized Epinephrine)
- Angle Closure
- Increased IOP
- Cystoid Macular Edema
What is significant about the cystoid macular edema caused by Epinephrine?
It can –> swelling of central part of the retina –> blindness if not treated early
What is Phenylephrine?
A Direct Alpha 1 Agonist
What are the ocular uses of Phenylephrine?
- Mydriasis
- Decongestant
- Breaking Posterior Synchia to the lens
How long does Mydriasis occur with Phenylephrine?
Onset- 1hr
Duration- 7hrs
What drug is commonly used for DFE?
Phenylephrine
What is the role of the decongestant use of phenylephrine?
To differentiate Episcleritis from Scleritis
What are the ocular side effects of Phenylephrine?
- Lid Retraction
- Lacrimation
- Angle Closure
Why is phenylephrine not used for narrow angle dilation?
Because phenylephrine may –> Angle Closure, and it is harder to reverse its mydriasis
Which drug class worsens the sympathomimetic side effects of Phenylephrine?
MAOIs
Does Phenylephrine induce Cycloplegia?
No- because the ciliary body muscle has few Alpha receptors
Is the Active Light reflex present with Phenylephrine?
Yes- because the Parasympathetics to the Iris Sphincter are still intact
What is Apraclonidine?
Direct Alpha Adrenergic Agonist; some specificity for Alpha 2
What is the ocular use of Apraclonidine?
- Treatment of glaucoma
- Fast reduction of High IOP
- Pre and Post-Op Glaucoma/Laser Treatment
How long does the reduction of IOP with Apraclonidine last?
3-5 hours - but fast acting
Why is Apraclonidine not used for long term use?
Significant Drift
What are the 3 Mechanisms by which Apraclonidine reduces IOP?
- Binds presynaptic A2 receptrs –> Decreased NE, so less stimulation of B2 on the Ciliary Process –> Decreased Aq Production
- Binds postjunctional A2 receptors in the Epithelium of the Ciliary Process –> reduction of intracellular cAMP –> Decreased Aq Production
- Binds A2 receptors on the episcleral veins –> Dilation –> increased Aq outflow through the uveoscleral pathway
What are the side effects of Apraclonidine?
Dry Mouth, HA, Lethargy
What are the ocular side effects of Apraclonidine?
- Allergic RXN and Red Eyes
2. Mydriasis, Conjunctival Vascular Constriction, Lid Retraction (mild- due to some Alpha 1 Stimulation)
What is Brimonidine?
A Direct acting Alpha 2 Agonist (Highly Selective)
What is the treatment for Normal Tension Glaucoma?
Brimonidine
What is the secondary function of Brimonidine?
Primary Open Angle Glaucoma
How does Brimonidine similar/different from Apraclonidine?
Similar- Reduces IOP (same mechanism)
Different- Less long term drift (b/c more selective for Alpha 2), less Allergic RXN
What are the side effects of Brimonidine?
- Dry Mouth
- HA
- Lethargy
What are the ocular side effects of Brimonidine?
- Allergic RXN (less severe than Apraclonidine)
* *No Alpha 1 effects because so selective