2 - Autonomic Drugs Flashcards
Basics: SNS vs PNS
- location of cell bodies
- pre vs post ganglionic
- receptor types
SNS: thoraco-lumbar, shorter pre-gang, releases epi/norepi, alpha/beta receptors
PNS: cranio-sacral, longer pre-gang, releases ACh, muscarinic receptors
Cholinergic receptors in the eye
Iris sphincter (M3) = miosis
Ciliary muscle (M2/3) = accommodation
Lacrimal gland (M2/3) = tear production
Adrenergic receptors in the eye
Iris dilator (a1) = dilation
TM (B2) = relaxation, incr outflow
Ciliary muscle (B2) = relaxation (opposes accomm)
NPCE (B2, some B1) = incr AH formation
CB vasculature (a2) = constricts, reducing AH formation
Ocular cholinergic agonists
- promote __ acitivity
- 3 main structures that rec’v this innerv
- therapeutic uses
PNS
Sphincter, ciliary muscle, lacrimal g
Tx of glaucoma and accomm ET, less commonly for miosis prior to surgery or for pupillary testing
Pilocarpine
- type of drug
- use and effectiveness
Direct cholinergic agonist (PNS)
Decr IOP, 30% reduction
Pilocarpine
- MOA
- uses
Stimulate longitudinal muscle of CB -> pulls posteriorly on SS -> opens TM for incr corneoscleral outflow and decr IOP
After an angle closure attack (e.g. IOP is in low 20s)
Preparation for LPI
Fixed dilated pupil: 1% used to differentiate 3rd nerve palsy (will constrict) from sphincter tear
Acute dilated pupil: 0.125% diagnoses ADie’s (will constrict due to supersensitization)
Pilocarpine
-main SE
Browache/HA and myopic shifts - a ton of accomm turned on
Miosis
Cataracts: long-term use
RDs: rare, due to retinal break -> detachment from ciliary muscle pulling on ora
Secondary angle-closure: contraction of ciliary m + secondary relaxation of lens zonules -> lens moves anteriorly
Pupillary block: combo of forward movement and myopic shift, etc.
Edrophonium
- type of drug
- MOA
- use
Indirect cholinergic agonist (PNS)
AChase inhibitor = incr ACh
Diagnosis of Myasthenia Gravis
- rapid onset (30-60s), short duration (10m)
- if ptosis improves 1-2m after injection = (+) for MG
Neostigmine
- type of drug
- MOA
- use
Indirect cholinergic agonist (PNS)
AChase inhibitor = incr ACh
Treatment of Myasthenia Gravis
-also limb strength eval in MG suspects
Echothiophate
- type of drug
- MOA
- use
Indirect cholinergic agonist (PNS)
Irreversible AChase inhibitor = incr ACh
Diagnosis/treatment of accommodative ET
Rarely used for glaucoma
Pyridostigmine
- type of drug
- MOA
- use
Indirect cholinergic agonist (PNS)
AChase inhibitor = incr ACh
Treatment of Myasthenia Gravis
Recall ocular characteristics of Myasthenia Gravis
Ptosis - worse with BBs
Diplopia worse at end of the day
Drug that’s administered IV to reverse effects of irreversible AChase inhibitors
Drug that’s administered to reverse muscarinic effects of reversible AChase inhibitors
Pralidoxime/Protopam
Atropine
Ocular cholineric antagonists
- mnemonic to remember all
- mnemonic for order of cyclo and mydriatic effects
- MOA for all
- SE for all
- toxicity
STop ACH
ASH CiTy
Bloch ACh at muscarinic sites in CB/iris
Dry eye, mydriasis, incr IOP
Hot as a hare, red as a beet, dry as a bone, mad as a hatter, blind as a bat
Scopolamine
- type of drug
- use
- SE
- contraindications
Cholinergic antagonist (decr PNS)
Similar to atropine, but rarely used due to severe SE
CNS toxicity (penetrates BBB)= hallucinations, amnesia, unconsciousness, confusion, incoherence, vomiting, urinary incontinence
Same as atropine
Tropicamide
- type of drug
- use
- SE
- contraindications
Cholinergic antagonist (decr PNS)
Dilation: fastest onset (25m) and shortest duration (6h), stronger mydriatic than cycloplegic
-cycloplegic effects are dose-dependent, mydriatic are not
Very safe overall
Atropine
- type of drug
- use
- SE
- contraindications
Cholinergic antagonist (decr PNS)
Treatment of uveitis (homatropine better here)
Amblyopia penalization: mild-mod (acuity 20/100 or better)
Too prolonged for routine dilation: onset 60-180m, duration 7-12 days
Safe if correctly dosed
Toxicity = dry mouth (1st sign), dry flushed skin (vasoconstriction), rapid pulse, disorientation, fever (CNS hypothalamus effects)
-think SNS effects for toxicity
Special caution in pts with Down’s syndrome, small children, elderly
Cyclopentolate
- type of drug
- use
Cholinergic antagonist (decr PNS)
Cycloplegia: fastest onset (45m) and shortest duration (24h)
-better than homatropine, similar overall effects to atropine
-mydriasis max at 45m
Tx of anterior uveitis + synechiae prevention
Homatropine
- type of drug
- use
Cholinergic antagonist (decr PNS)
Standard for tx anterior uveitis
- dilates pupil + keeps it mobile = prevents synechiae
- paralyzes ciliary/sphincter m = reduces pain
- constricts iris/ciliary vasculature = stabilizes BAB, limit cells/flare
Prolonged mydriatic and cycloplegic (weak cyclo)
Botulina toxin
- type of drug/MOA
- use
Somatic drug, blocks ACh release at NMJ to inhibit muscle contraction
Blepharospasm treatment - temporary (few mo)
Strabismus correction - permanent
Phenylephrine
- type of drug
- MOA
- uses (4)
- 10% use, SE, contraindications
Adrenergic agonist (SNS)
Alpha1 agonist
Dilation of radial muscle without cycloplegia
- 2.5% used with tropicamide for routine dilation
- in isolation cannot produce fixed dilation
Palpebral widening: acts on Mullers, good for BIO
Differentiate scleritis and episcleritis: blanching of conj vessels
Horners diagnosis: 1%
10% = Breaking posterior synechiae
- limited due to adverse CV effects (HTN, arrhythmia)
- contra: MAOIs, TCAs, atropine, Grave’s disease
Naphazoline
- type of drug
- MOA
- use
- SE
Adrenergic agonist (SNS)
Alpha > beta effects
Topical ocular decongestant - constrict conj BVs
Potential to depress CNS
Tetrahydrozoline
- type of drug
- MOA
- use
- SE
Adrenergic agonist (SNS)
Alpha > beta effects
Topical ocular decongestant - constrict conj BVs
Potential to depress CNS
Fixed dilated pupil due to alpha effects on radial muscle
Brimonidine
- type of drug
- MOA
- use
- SE
- contraindications
Adrenergic agonist (SNS)
Highly selective alpha2 agonist = decr AH production, incr uveoscleral outflow
Glaucoma (TID, short duration): IOP lowering + long-term use
-neuroprotective properties shown in crushed rat nerve model
Miosis: reduce glare, halos, other night vision symp post-refractive surgery
Follicular conj-itis: largely eliminated SE with Alphagan-P (purite preservative)
Systemic = dry mouth
MAOIs
Apraclonidine
- type of drug
- MOA
- use
- SE
Adrenergic agonist (SNS)
Alpha2 agonist
Weak alpha1 = only dilates if Horner’s
Control IOP spikes before/after ocular surgery
Acute angle closure attack: rapid, potent decr in IOP
-IOP reduces 30-40%
-onset 1h, peak 3-5h
-not effective in chronic therapy due to SE
Diagnosis of Horner’s
Tachyphylaxis: loses efficacy over time
Long-term use =allergic response
Horner’s diagnosis
1) cocaine = no dilation, apraclonidine = dilation
2) hydroxyamphetamine = dilate if preganglionic, phenylephrine = no dilation if preganglionic
Beta-blocker effects
- CNS
- CV
- pulmonary
- GI
- reproductive
Fatigue, disorientation, depression
Bradycardia, arrhythmia, syncope
Bronchoconstrict = dyspnea, wheezing, spasm
Nausea, vomiting, diarrhea, ab pain
Erectile dysfunction
MOA of beta adrenergic receptor blockers for glaucoma
Block B2 at NPCE to decr AH production
Timolol
- type of drug
- MOA
- use
- dosing
- SE/pharmacokinetics
- contraindications
Adrenergic antagonist (decr SNS)
Non-selective BB
Most effective at lowering IOP (~25%)
- unstable
- also available in gel form as timoptic xe
0.25% once daily in the morning
Crossover effect (unique!): reduces IOP in contralateral eye Long-term drift: extended use -> IOP gradually rises Short-term escape: IOP initially lowers, but returns to normal within weeks of starting therapy
Caution in diabetes (masks hypoglycemia), hyperthyroidism (masks signs/symp), and myasthenia gravis (exacerbate fatigue)
Timolol combo drugs available
Cosopt = timolol 0.5% + dorzolamide 2.0%
Combigan = timolol 0.5% + brimonidine 0.2%
Both dosed Q12h
Carteolol
- type of drug
- MOA
- use
- SE
Adrenergic antagonist (decr SNS)
Non-selective BB
Not used clinically, poor IOP reduction vs other BBs
Intrinsic sympathomimetic activity: reduce nocturnal bradycardia, generally less stinging than timolol
Modest reduction in cholesterol (very small)
Potentially less SE than other BBs
Betaxolol
- type of drug
- MOA
- use
- SE
Adrenergic antagonist (decr SNS)
Cardioselective B1 blocker
-limits risk of respiratory effects
Questionable neuroprotective qualities
Overall less effective than timolol
Can worsen CHF
Levobunolol
- type of drug
- MOA
- use
Adrenergic antagonist (decr SNS)
Non-selective BB
Similar to timolol in effectiveness
Metipranolol
- type of drug
- MOA
- use
Adrenergic antagonist (decr SNS)
Non-selective BB
Not used due to ineffectiveness vs other BBs
