Test 2 part V Flashcards
Indirect Acting Cholinomimetics cause _____ nerve activation and effects on the ________.
Vagal; Vasculature
What are the effects associated with Vagal Nerve Activation via Indirect Acting Cholinomimetics?
- Decreased CO due to bradycardia, dec atrial contraction, and some decreased ventricular contraction
- Prejunctional inhibition of NE release due to negative feedback on SNS ganglia (!!!!)
- Post-junctional inhibition of SNS effects
What are the effects associated with Vasculature effects from Indirect Acting Cholinomimetics?
- Most lack cholinergic innervation
- Increase in SNS tone due to Ach on sympathetic ganglia (increased NE in vasculature). (Remember: we have a dominant PNS System. Ach acts on both SNS and PNS. Inc Ach can have an effect of vasoconstriction due to Ach on sympathetic ganglia)
MR > NR in ______ (all MR Subtypes)
NR > MR in _______
Brain; Spinal Cord
A moderate dose of an Indirect Acting Cholinomimetic will cause what effects on the CV system?
- Bradycardia
- Decreased CO
- Increased PVR
- Increased BP
A high (toxic) dose of an Indirect Acting Cholinomimetic will have what effects on the CV system?
- Marked bradycardia
- Significantly decreased CO
- Severe hypotension
What is the prototype drug for antimuscarinics?
Atropine
Is Atropine tertiary or quaternary?
Tertiary
What is the mechanism of action for antimuscarinics?
Reversible blockade of the muscarinic receptor.
Prevents the release of IP3 and blocks the inhibition of adenylyl cyclase.
Muscarinic Blockers block ________ cholinoreceptor agonists more effectively than _______.
Exogenously administered; endogenously released Ach
Low doses of Atropine result in initial ______ as a result of the pre-junctional ____ on vagal postganglionic fibers that normally limit Ach release.
Bradycardia; M1
Which Drug?
1. A competitive antagonist at all MR
2. Prevents release of IP3 and inhibition of adenylyl cyclase.
3. Tertiary Amine
Atropine
Which Drug?
1. A competitive antagonist at muscarinic receptors.
2.Tertiary amine
3. Transdermal patch given for PONV and/or motion sickness (patch education needed)
Scopolamine
Which Drug?
1. A competitive, non-selective antagonist at M receptors
2. Reduces/prevents bronchospasm.
Ipratropium
Which Drug?
1. Blocks Ach at PNS sites in smooth muscle, secretory glands, and CNS, preventing salivation
2. Quaternary amine
Glycopyrrolate
Which Drug?
1. inhibits Ach-E, increases available Ach.
2. Tertiary amine - well absorbed throughout
3. Given for reversal of CNS anticholinergic syndrome
Physostigmine
Which Drug?
1. Forms covalent bond with Ach-E
2. Increases PNS activity, longer-acting.
3. Quaternary amine - does not enter CNS
4. Used in tx of Myasthenia Gravis
Neostigmine
What causes Cholinergic Poisoning?
Too much Acetylcholine
What are the S/Sx of Cholinergic Poisoning?
SLUDGE: Salivation, Lacrimation, Urination, Diarrhea, inc Gi motility, Emesis, pulm edema
A Medical emergency due to Insecticides, Wild mushrooms, or Nerve Gasses. Has a rapid onset of 30 min.
Cholinergic Poisoning
What is the treatment for Cholinergic Poisoning?
- Tertiary Antimuscarinic (Atropine) for CNS and peripheral effects
- Benzos if seizures
- Cholinesterase Regenerators
What are the S/Sx if too much Muscarine?
N/V/D, urinary urgency, salivation, sweating, cutaneous vasodilation, bronchial constriction
What is the treatment for too much Muscarine?
Atropine
What are the S/Sx of too much Nicotine?
Seizure, coma, death, respiratory paralysis. Fatal dose = 40 mg
What is the treatment for too much Nicotine?
Symptom management (Nicotine is rapidly metabolized)
Which cholinergic drugs (agonists or antagonists) are Tertiary (Can cross the blood-brain barrier)
PAS:
Physostigmine
Atropine
Scopolamine
T/F: if you give a muscarinic blocker, you will inhibit/slow digestion
false; gut motility still active d/t modulation of local hormones and NANC within the ENS
What clinical conditions are treated with Cholinomimetics?
- closed angle glaucoma
- accomodative esotropia
- postop ileus
- congenital megacolon
- urinary retention
- neurogenic bladder
- reflux esophagitis
- dry mouth
- myasthenia gravis
- alzheimers
What medication is used in the Tensilon Test to differentiate between a Myasthenia Crisis and a Cholinergic Crisis?
Edrophonium (an indirect acting cholinomimetic - simple alcohol)
What clinical conditions would you use a Muscarinic Blocker for?
- mydriasis for eye exam
- travelers diarrhea
- urinary urgency and/or incontinence
- urolithiasis
- syncope
- chagas dz
- graves dz
- copd/asthma recovery
- parkinsons
- motion sickness
What is the treatment for Atropine Intoxication?
Neostigmine
What are the S/Sx of Atropine Intoxication?
- dry mouth
- mydriasis
- tachycardia
- hot/flushed skin
- agitation
- delirium
- fever
- behavioral disturbances
- lethal arrhythmias
There is no effective method for blocking the ______________ effect of cholinesterase inhibitors.
Nicotinic (remember: Nicotinic receptors are in SNS and PNS)
Which sympathetic receptor is most DOMINANT in the heart?
Beta 1
Adrenergic stimulation on the heart ___________ coronary blood flow
Increases
Direct Acting Cholinomimetics cause direct ______ of the SA and AV node.
Slowing
The slowing of the SA/AV node is opposed by what?
Reflex SNS discharge from the decrease in MAP
Indirect Acting cholinomimetics will cause prejunctional inhibition of _____ release, but secondarily will increase the _____ in the vasculature (as a response)
NE; NE
Which adrenergic receptor causes arterial and venous vasoconstriction = increased BP?
Alpha 1
What are the effects of Alpha 1 Stimulation?
- Increased arterial tone/resistance
- Decreased venous capacitance
- Decreased HR due to baroreceptor reflex
Ex: Phenylephrine
Stimulation of which Adrenergic receptor inhibits Renin secretion?
Alpha 2
Stimulation of Beta 1 receptors does what?
Increases CO by increasing contractility and direct stimulation of the SA node to increase HR.
Which adrenergic receptor stimulates Renin secretion?
Beta 1
Which adrenergic receptor decreases SVR through vasodilation of certain vascular beds?
Beta 2
What is the effect of Alpha 1 agonism on the eye?
Reduces outflow of aqueous humor and
increases intraocular pressure.
What is the effect of Beta Blocker administration on the eye?
Reduces intraocular pressure through decreasing the aqueous humor.
Why do you want to avoid stopping a beta blocker rapidly in a patient with HTN?
To avoid rebound HTN
What is the effect of Alpha Blockers on the CV System?
Lowers BP and SVR
Which drug often causes orthostatic hypotension and reflex tachycardia?
Alpha Blockers
You should avoid which class of drugs in asthmatic patients?
Beta Blockers (bronchoconstriction)
