topic 20 Flashcards
What are 6 types of cholinergic drug agents?
Directly acting muscarinic agonists
Muscarinic Antagonists
Anticholinesterases
Ganglionic Stimulant
ganglionic Antagonist
Neuromuscular blockers
What are two types of directly acting ACh agonists? Name 4 examples of one and 2 examples of the other.
Choline Esters: ACh, Methacholine, Carbachol, Bethanechol
Alkaloids: Pilocarpine, Cevimeline
What is the susceptibility to cholinesterases of the 4 choline esters? What is each primarily used for? Do they stimulate nicotinic receptors?
ACh-Very susceptible to Ach. the others not as much.
Methacholine-Used to diagnose bronchial hyperreactivity (not used in much else, acts strongly on heart)
Carbachol-Used mainly in research. Acts strongly on nicotinic receptors and thus can be used for that.
Bethanechol-The main one used clinically. It is not hydrolyzed by AChE. It is used to stimulate the motility of GI tract and contract the urinary bladder, often post-operatively.
What are the 2 alkaloids used?
Pilocarpine and Cevimeline
How is Bethanechol taken? What is its absorption? Distribution? What receptor does it favor? What does it do?
SC or PO
Poor lipid solubility
Does not cross BBB
Favors M3
Enhances function of GI tract and urinary bladder, especially post-op
How is Pilocarpine taken? What is its absorption? Distribution? What does it do? What is it used to treat?
PO or eyedrops
Well absorbed
Good lipid solubility
Marked stimulation of saliva and sweat
Used in both narrow angle and wide angle glaucoma
What receptor does Cevimeline work on? What drug is it simliar to? What does it do? What is sjogrens syndrome? Treatment of it?
Synthetic M3 selective agonist
Similar to Pilocarpine
Used for treatment of dry mouth associated with Sjogrens Syndrome (autoimmune where moisture producing glands are destroyed) or radiation damage of salivary glands.
Pilocarpine also used to treat sjogrens syndrome.
What is glaucoma? What are the two types? How are each treated?
Ocular disease characterized by an elevation of intraocular pressure leading to possible retinal damage
Primary open angle Glaucoma: More common. Problem in trabecular network so aqueous humor cant get out into schlemms canal. But angle is intact. This is usually treated step-wise with drugs. Pilocarpine is part of the 3rd step.
Narrow angle glaucoma: Less common. Iris bows forward and makes contact with cornea so aqueous humor cant get to anterior chamber. Emergency increased pressure. Pilocarpine used immediately followed by surgery.
What are the side effects of muscarinic agonists
Salivation, Lacrimation, Nausea and vomiting, bradycardia, diarrhea, sweating, urination, hypotension, bronchospasm, CNS activation, Headache and visual disturbances, Pupils constricted
What are the contraindications of muscarinic agonists?
Asthma/COPD, Hyperthyroidism, Coronary insufficiency, Peptic Ulcer Disease, Obstruction of urinary bladder or Gi tract.
What are 5 muscarinic antagonists or belladonna alkaloids? What are the prototypes? How do they work? What happens w/o parasymp tone?
Atropine, Scopolamine, Ipratropium, Tolterodine/Oxybutynin
They are competetive antagonists at muscarinic receptors. The more parasymp tone at a receptor, the greater their effect.
What are the routes of admin. of atropine? How is it absorbed orally? What is it distribution? How is it metabolized?
PO, IM, IV, SC, opthalmic drops
Well absorbed orally
Well distributed, crosses BBB
40% hydrolyzed and conjugated
60% excreted
What are the routes of admin. of Scopolamine? What is it distribution? How is it metabolized?
PO, IM, IV, SC, eyedrops,patches
Crosses BBB
Metabolism similar to atropine
What are the routes of admin. of Ipatropium? Absorption? What is it distribution? ?
Only inhaled
Poorly absorbed, doesn’t cross membranes well
Doesn’t cross BBB
What is the effect of muscarinic antagonists on the CNS? What are some therapeutic uses? How do scopolamine and atropine differ in their effects?
Atropine stimulates CNS and causes hallucinations. Scopolamine depresses CNA (drowsiness, euphoria). Antitremor in parkinsons.
Sleeping pills (scopolamine)
Motion sickness (scopolamine)
Parkinson’s
Sedation prior to surgery (scop)
Sedation during labor (scop-truth serum)
What is the effect of muscarinic antagonists on the eye? What are some therapeutic uses?
Dilation and paralyzes accomodation (looking close) (cycloplegia).
Opthalmalgic use (eye exams)
mydriatics and cycloplegics
What is the effect of muscarinic antagonists on the respiratory system? SM in general? glands in general? What are some therapeutic uses?
SM in general is relaxed, so bronchioles are relaxed (opening airway). Gland secretions are inhibited, so resp tract gland secretion is inhibited.
Inhibition of secretions
Reduce or prevent vagal overactivity
Cold Remedies
Asthma
COPD
What is the effect of muscarinic antagonists on the Heart/BP? What are some therapeutic uses in CV system?
In heart, low doses—>slight bradycardia (due to vagal stimulation in CNS), but most tachycardia via blockage of SA node. No great effect on BP.
Atropine always in crash cart. After MI, it combats symptoms such as
Sinus Bradycardia
SA Arrest and SA Block
What is the effect of muscarinic antagonists on the GI Tract? Sphincters in general? What are some therapeutic uses?
Since SM is relaxed–>less motility and tone, less gall bladder secretion. Sphincters are blocked in general.
Inflammation (IBS and acute enterocolitis)
Travelers diarrhea
What is the effect of muscarinic antagonists on the bladder? What are some therapeutic uses?
Urinary incontinence in elderly using tolterodine and oxybutyin
Child enuresis
What are some side effects of Atropine and other muscarinic antagonists in order of when they appear with increasing doses
Less salivation (dry mouth), inhibition of sweating, Micturition speed lowered, acceleration of heart, dilation of pupil, blurring of vision, speech disturbed, headache, restlessness and fatigue, hot skin, difficulty swallowing, reduced peristalsis, ataxia, hallucinations, delirium, death.
What are atropine, scopolamine, ipratropium, tolterodine, and oxybutynin primarily used for? Why do some have less side effects?
Atropine-counteract muscarinic toxicity, mydriatic, reversal of bradycardia or cardiac arrest
Scopolamine-motion sickness
Ipratropium-Bronchodilator in asthma and copd
tolterodine/oxybutynin-reduce involuntary voiding.
The last 3 are used locally and have poor penetration across membranes and thus have fewer side effects.
What are the two types of cholinesterases? Where are they primarily located? What is their substrate selectivity? How are indirect ACh agonists different from direct?
AChE: Located in all cholinergic synapses (therefore it works in CNS and Neuromuscular synapses as well unlike the direct agonists). Specific for ACh.
Plasma Cholinesterase: Located in plasma (also intestines, etc.). Selective for ACh, succinylcholine, and local anesthetics
What are 7 Reversible AChE inhibitors?
Edrophonium, Physostigmine, Neostigmine, Pyridostigmine, Tacrine/Donepezil (alzheimers), demecarium (opthalmic)