Sympathetic System Ocular Drugs - 10/3
What does the "P" stand for in Alphagan-P ? Is this drug still around today?
"P" stands for purite which was the preservative used in the drug when originally came out to market in 1996 after patent expired was brought to market wout the purite preservative and has been reformulated a few times
10% phenylephrine should avoid being used in which two patient populations? Phenyl in general should be avoided in what other populations?
10% avoided in neonates / elderly h/ myocardial infarctions, uncontrolled diabetes (esp TI), ateriosclerosis, etc
______% phenylephrine can be used for pre-LASIK vasoconstriction to prevent bleeding during sx ____ % phenyelphrine can be use to evaluate for Horner's
10% phenyl for pre-LASIK vasoconstriction 1% for Horner's eval
What are the two prominent concentrations Phenylephrine dilating gtt come in?
2.5% 10%
Phenylephrine mildly suppresses one's accommodation by about _______ diopters and causes ________ via Mueller's stimulation
2D LID RETRACTION
In general some adverse effects of sympathomimetic drugs on the central nervous system are ________ , fear, headaches, or the potential for ________ strokes
ANXIETY / fear potential for hemorrhagic strokes
_______ is an alpha2 adrenergic agonist drug originally approved for glaucoma treatment as "Alphagan-P" in 1996
Brimonidine
What are the 3 major mechanisms of sympathetic vasodilation? What about vasoconstriction? (name the structural mechanism and receptors present)
DILAITON: Endothelial cell receptors - alpha1/2/3 Smooth muscle cell receptors - beta Nerve cell terminal receptors - alpha2 / beta CONSTRICTION smooth muscle cell receptors - alpha1/2
T/F: Phenylephrine can cause a range of adverse side-effects such as photophobia, rebound miosis and congestion, allergic reactions, and systemic hypertension w tachycardia
FALSE --> causes BRADYCARDIA w systemic hypertension (heart slows down in response to increased bp when phenyl gets into circulation)
_______ is an indirect-acting sympathomimetic agent that promotes NE release from nerve terminals and reduces reuptake, causing contraction of the iris radial muscles and a mydriatic response
Hydroxyamphetamine **also has negligible direct recetpro activation of alpha/beta receptors
In general, some adverse effects of sympathomimetic drugs on the cardiac system are _______ heart rate, arrhythmias, and _______ blood pressure
INCREASE heart rate ELEVATED bp
__________ are the name of a class of adrenergic agonistic drugs (gtt) which have an enhanced selectivity for alpha-1 receptors of the eye ; what is one disadvantage of using this drug type?
Imidazolines **exhibit tachyphylaxis (dec. response to a drug after repetitive administration)
Does the 1% hydroxyamphetamine formulation cause any accommodative suppression for the patients?
NO
Can anticholinergic agents be used for sectoral dilations?
NO bc relaxes sphincter 360-degrees so need sympathomimetic Phenyelphrine for this job bc contracts only portion of iris dilator! **cannot use tropic or Paremyd for this then
_______ is an example of a sympathomimetic Imidazoline eye drop that works by acting as an alpha-2 adrenergic agonist
Naphazoline EX: Clear Eyes reduces output of sympathetic nervous system by inhibiitng release of sympathomimetics on ocular structures **is not 100% selective
Give 3 examples of imidazoline OTC gtt used to treat red-eye
Naphazoline EX: Clear Eyes 0.012 or 0.02% Tetrahydrozoline EX: Visine 0.05% Oxymetazoline
Which adrenergic agonist compound was originally used as the active ingredient in visine and then was d/c and eventually re-used by Upneeq? Why? What does Upneeq gtt do?
Oxymetazoline now used in Upneeq @ 0.1% (vs 0.025% in Visine LR) as first FDA approved drug for blepharoptosis as it is an adrenergic agonist which stimulates interpalpebral size to increase due to stimulation of Muller's muscle
_________ is an example of a sympathomimetic Imidazoline eye gtt that works as an alpha-1 agonist and an alpha-2 partial adrenergic agonist
Oxymetazoline EX: Visine LR 0.025% that was d/c in 2015
What are the two main sympathomimetic amine drugs used for ocular dilation ?
Phenylephrine **direct Hydroxyamphetamine (in Pyramed) **indirect-acting
_________ drugs are those that are antagonistic to the sympathetic nervous system
Sympatholytic drugs
T/F: Both phenylephrine and hydroxyamphetamine gtt can be used in the diagnostic process when detecting Horner's Syndrome
TRUE!
________ is an example of a sympathomimetic Imidazoline eye gtt that works by acting as an alpha-1 adrenergic agonist
Tetrahydrozoline EX: visine 0.05%
Does IOP reduction occur when using phenyelphrine gtt? Why or why not?
Yes but MINIMALLY bc phenyl is mostly an alpha1 selective agent but in case that binds alpha2 receptors is can decrease IOP / aq production
Why is Lumify's formulation as an adrenergic agonist so unique compared to the other "redness relieving" drugs out on the market such as Visin
bc Lumify uses low concentration of brimonidine which is an alpha2 agonist ==> causes constriction of ocular VENULES so reduces redness while still allowing O2 to reach ocular surface ; meanwhile drugs like Visine work as alpha1 agonists which constrict ARTERIOLES and thus also deprive the eye of O2 / nutrients necessary for proper maintenance
Why is phenylephrine never used along as a dilating drop?
bc its mydriatic response takes about 45-60 minutes and thus it is always combine w an anticholinergic for faster / greater dilation
Why should you check the AC for cells and flare BEFORE putting any dilating drops (such as phenyl) in one's eyes?
bc phenyl can cause anterior chamber pigment liberation and this may be confused w "cells & flare" if not previously documented before putting drops in!!
_______ receptor stimulation occurs when much higher doses of Phenylephrine are used which then causes the eyes to get red
beta receptor stimulation occurs @ much higher doses of PE (normal doses use alpha-1 receptor selectivity) ==> vasodilation and redness of eyes
Phenylephrine induces conjunctival ________ and can thus be used to distinguish episcleritis from scleritis cases
conjunctival BLANCHING (vasoconstriction) - alpha1 mechanism **if episcleritis, will see constriction when using this gtt... if scleritis, will not see constriction w this gtt
What is Pyramed?
dilating drop containing 1% hydroxyamphetamine (indirect acting sympathomimetic amine) and 0.25% tropicamide (parasympatholytic)
What is one adverse effect of sympathomimetic drugs on the hepatic system? What about the immune system? Respiratory system?
hepatic- elevated blood sugar immune - immunosuppression respiratory - pulmonary edema
What is the most recent reformulation of the original "alphagan-P" drops and how is this reformulation used today?
most recent ==> brimonidine sln is reformulated in 2018 as LUMIFY w brimonidine being at 0.025% instead of 0.1/0.15% Lumify is used to reduce ocular surface redness today
In general, some of the adverse ocular sympathomimetic drug responses include photophobia, _______ of accommodation, and _______ depth of focus
suppression of accommodation / near blur decreased depth of focus
Phenylephrine has synergistic effects with what 3 other drug classifications? What antagonistic effects does it have w 2 other drug classifications?
synergistic: - monoamine oxidase inhibitors (MAOIs) - tricyclic antidepressants (TCADs) - atropine antagonistic: - methyldopa (anti-hypertensive) - beta blockers
Briefly describe why phenyephrine is a useful adjunct dilating agent in older patients; is this drop needed for younger patients too?
with age the sympathetic tone of our muscles decrease causing age-related miosis thus, a simple parasympathetic paralytic drop (anticholinergic agent) alone does not provide enough dilation for a proper fundus exam so sympathomimetic drug phenyelphrine (2.5%) is used to heighten dilation by stimulating greater sympathetic response of dilator muscle this is NOT always needed w younger patients who have greater sympathetic tone and can just dilate w anticholinergic agent
