mydriatics and cyclopegics Flashcards
what are MAO and COMT?
enzymes of catecholamine metabolism ( e.g. breakdown epinephrine and norepinephrine)
what are catecholamines?
biogenic amines derived from tyramine (important in sympathetic pathway)
what are three catecholamines?
dopamine, epinephrine, norepinephrine
the sympathetic branch is also known as the _________ branch
adrenergic
the parasympathetic branch of autonomics is also known as the ______ branch
cholinergic
what neurotransmitters are responsible for adrenergic branch of autonomics?
adrenaline, epinephrine, norepinephrine
what neurotransmitter is primarily responsible for cholinergic branch of autonomics?
acetylcholine
____ is a precursor of E and NE
dopamine
epinephrine (E) is secreted into the ____ by the _____ gland
bloodstream, adrenal
which sympathetic neurotransmitter is classically blood borne and which is classically neuronal?
epinephrine, NE respectively
because norepinephrine is _____, it is the primary catecholamine generated by nerves responsible for sympathetic nerve impulses
neuronal
_____ is also found in the blood stream in __x higher concentrations than epinephrine
norepinephrine, 3x
which sympathetic neurotransmitter is secreted at synaptic clefts?
norepinephrine
acetylcholine in parasympathetics is made of a ____ group and _____ molecule
acetate, choline
the autonomic nervous system has ___ branches which are?
sympathetic adrenergic, sympathetic cholinergic, and parasympathetic cholinergic
do somatic nerves leaving the spine synapse with ganglia?
no
somatic nerves are myelinated or unmyelinated?
myelinated
the target receptor of somatic nerves are mainly what?
skeletal muscle
parkinson’s is treated with _____ drugs
anticholinergic
does the autonomic nervous system have myelinated ganglion fibers?
no
ganglia acetylcholine (ACh) stimulates ___ receptors in autonomic system
nicotinic
at end terminal organ, ACh neurons stimulate __ receptors in somatic system
nicotinic
at end terminal organ, ACh for which two pathways stimulates M receptors?
parasympathetic cholinergic and sympathetic cholinergic
at the end terminal organ, __ stimulates __ receptors in the sympathetic adrenergic pathway?
NE, alpha and beta
what are two examples of target tissue for sympathetic cholinergic?
sweat glands, some vessels
sympathetic ganglia are closer to the ___ where as parasympathetic ganglia are closer to the _____
spine, terminal organ
what 2 effects does alpha 1 have on the body?
mydriasis, vasoconstriction in GI tract
what 3 effects does alpha 2 have on the body?
decrease in aqueous outflow, decrease in signals (signal inhibition), decrease in insulin release
what 2 effects does beta 1 have on the body?
increase contractility and conduction of heart. remember B1= heart
what 6 effects does beta 2 have on the body?
increase in aqueous production, increase insulin release, vasodilation, bronchodilation, glycogenesis, relaxation of ciliary body
norepinephrine is best at what three things and why?
mydriasis, vasoconstriction, cardiac contraction/conduction b/c NE predominates over E for alpha 1 and = to E for B1 effects
epinephrine is stronger than NE at ___ and ___ receptor ?
beta 2 and alpha 2 (E=NE for B1). beta 2 for epinephrine is strongest!!
E and NE can be metabolized by which two enzymes?
MAO and COMT
in sympathetic nerve activity, ___is absorbed by the nerve in the first step
tyrosine
in sympathetic nerve activity, once in the nerve terminal, tyrosine is converted to ___ which is then converted to ____
dopa, dopamine
the dopamine is packed into ____ and then some is converted to ____
vesicles, NE
once the NE vesicles accumulate, you get an _____ that triggers ___ to enter the nerve terminal and cause the fusing of vesicles with nerve wall and the ___ of NE neurotransmitters into the external environment
action potential, calcium, release
what are three things that NE can do once released into the external environment?
- go into post-synaptic nerve terminal and COMT degrades it
- NE can stimulate post synaptic alpha/beta receptors or alpha receptors on the presynaptic receptors-causing inhibitory signal (which thus blocks calcium dependent degranulation
- some NE remaining in the synaptic cleft will be reabsorbed by nerve that released it and broken down by MAO
what is the amino acid for stress hormones?
tyrosine
phenylalanine is a precursor for ____ and ____
tyrosine, melanin
name 4 ocular adrenergic effects
mydriasis, increase in palpebral aperture (stimulation of meuller’s muscle), modulate aqueous generation by ciliary body, suppress accommodation
list best to least effective ways to find angle estimation
gonioscopy > van herick > shadow test
___ and ___ commonly have large angles
myopes and aphakes
name 6 factors that cause REDUCED sensitivity to dilation
age-related miosis, unstable diabetes, posterior synechiae, post-op pupils, dark irides, pseudoexfoliation syndrome
what is something that causes INCREASED sensitivity to dilation?
down syndrome
4 poor dilation candidates are?
pregnant women, homocystinuria and marfan’s syndrome (have week fibers and lens can dislodge and fall into eye), pigmentary/exfoliative glaucoma (leads to transient IOP elevation)
contraindications for dilation (4)?
very narrow angle, angle closure history, iris supported intraocular lens, subluxated lens or IOL
phenylephrine is mainly selective for which receptor type?
alpha receptors
phenylephrine activity includes what three things?
mydriasis, contraction of iris radial muscle, indirectly cause NE vesicles to fuse and release neurotransmitters
what are 5 phenylephrine indications for use?
used for mydriasis, conjunctival blanching, mild accommodation (~2D), lid retraction and IOP reduction
what are 4 special uses of phenylephrine?
posterior synechiae breakage (10% formula), pre-LASIK vasoconstriction (10% formula), inhibition of iris cysts caused by echothiophate, horner’s evaluation
3 synergistic phenylephrine drug interactions?
MAOIs, TCADs, atropine
2 antagonistic phenylephrine drug interactions?
methyldopa, beta blockers
7 phenylephrine adverse effects?
photophobia, blur, glare, allergic dermatoconjunctivitis, rebound miosis and congestion, anterior chamber pigment liberation, bradycardia
6 contraindications of phenylephrine?
avoid 10% in old/young, CVD, uncontrolled diabetes, aneurysm, advanced arteriosclerosis, idiopathic orthostatic hypotension
hydroxyamphetamine activity?
indirectly promotes NE release, contraction of iris radial muscles indirectly
M1 receptor in parasympathetic pathway is for what?
memory
M2 receptor is greater than M3 for what?
cardiac: decreasing contractility and conduction in the heart
M2=M3 receptor for what 2 things?
pancreatic acini/hormone secretion, respiratory increase in bronchoconstiction and secretion
M3 is greater than M2 for what two things?
iris miosis, ciliary body contraction and increase in aqueous outflow
M3 is the parasympathetic receptor that does what three functions?
emetic (vomiting), increase salivary gland secretion, vasodilation
what two enzymes break down acetylcholine?
acetylcholinesterase and butyrylcholinesterase (BChE)
where is BChE found?
circulating in plasma
where is acetylcholinesterase found?
at nerve terminals
what molecule in the parasympathetic nerve activity starts the process?
acetyl-CoA
in parasympathetic nerve activity, acetyl-CoA first comes in and combines with ___ to make ____
choline, ACh
ACh is packaged into vesicles and due to subsequent _____ entry into the nerve, it ___ with the membrane and ____ ACh into the external environment
calcium, fuses, releases
what acts by inhibiting calcium dependent degranulation of ACh?
botox (used for muscle paralysis)
how do anticholinergic agents function?
they block the parasympathetic response
name 5 anticholinergics
atropine, scopalamine, homatropine, cyclopentolate, tropicamide
is scopolamine a selective or nonselective drug used for _______?
non-selective, motion sickness
atropine is selective or non selective for __-receptors?
non-selective, for M receptors
homatropine is a semi-synthetic derivative of atropine meaning it is broken down ____ effectively and lasts ____ than atropine in the body
less, longer
tropicamide is moderately ____ receptor selective
M4
which is the most lipophilic anticholinergic?
cyclopentolate
which anticholinergic is the safest to use in clinic and most common dilated agent you use?
tropicamide
because atropine in non-selective for M receptors and some N receptors, it has less or more side effects?
more
cyclomydril is ______ + _____
cyclopentolate, phenylephrine
the cyclo drugs will _____ the ciliary muscle
paralyze
which anticholinegic do you use to dilate pts with uveitis and why?
atropine b/c it’s potent with long lasting effect
what anticholinergic is used as an alternative to patching in ametropic patients?
atropine
what are 3 ocular adverse effects of anticholinergics?
increase in IOP, angle closure risk, allergy
what are important systemic adverse effects of anticholinergics?
ABCDS: anorexia, blur, constipation, confusion, dryness, sedation, stasis of urine
what are two CNS medulla effects of anticholinergics?
decrease in parkinson tremor and decreased heart rate
4 synergistic drug interactions of anticholinergics? 2 others?
synergistic: anti-histaminics, tricyclic antidepressants, antipsychotics, botox
other: opioids, potassium supplements
7 contraindications for anticholinergics?
angle closure glaucoma and narrow angles, open angle glaucoma, down syndrome, albinism, cerebral palsy, spastic paralysis, iris supported IOL
3 classic indications for atropine?
anterior uveitis (for vasoconstriction b/c block parasympathetic actions), myopic progression (won’t accommodate and grow eye longer), amblyopia (penalizing good eye)
which anticholinergic has less flushing and dryness than atropine?
cyclopentolate
cyclopentolate can cause ____effects in darkly pigmented eyes
delayed/sustained effects that last longer
PAREMYD is a combo of which two drugs?
hydroxyamphetamine (adrenergic) and tropicamide (anticholinergic)
PAREMYD has a ____ recovery than phenylephrine+tropicamide and can be used for a ____ angle
faster, shallow
Do you need to pre-anesthetize cornea before using PAREMYD?
no
does age and iris pigmentation affect usage of PAREMYD?
no
unique adverse effect of PAREMYD
tachycardia
PAREMYD safer than tropicamide in what 3 situations?
diabetes, ideopathic orthostatic hypotension, chemical sympathectomy agents
2 tropicamide uses?
mydriasis, dose-dependent cyclopegia (can ramp up dosing)
which anticholinergic has less pigment-sensitivity than the others?
tropicamide
does hydroxyamphetamine surpress accommodation?
no! (phenylephrine does)
