Cholinergic Drugs: Muscarinic Agonists and Antagonists Lecture PDF and Cholinesterase Inhibitors Lecture PDF Flashcards
Bethanechol (urecholine) drug class and therapeutic uses (3)
-direct acting muscarinic agonist
- urinary retention
- GI paralysis
Bethanechol (urecholine) oral vs SC dose
Oral dose must be 40x SC dose to produce equivalent effects because it is charged impeding absorption across GI tract
Bethanechol (urecholine) ADR’s (2)
- very few
- can worsen cardiovascular symptoms in hypotensive patients
- high doses abdominal cramping and involuntary defecation
Bethanechol (urecholine) contraindications (3)
- gastric ulcers
- intestinal obstruction
- recent surgery of bowel
Cevimeline (exovac) function
Derivative of Ach actions similar to bethanechol, relieves xerostomia by allowing and promoting salivation
Pilocarpine function
Topical therapy of glaucoma (outdated) or treatment of dry mouth from sjogren’s syndrome
Acetycholine usage pharmacologically
Restricted due to acetycholiesterase destruction, lacks sensitivity and can stimulate all muscarinic and nicotinic receptors but is also rapidly destroyed by cholinesterases
Symptoms of muscarinic agonist poisoning (6)
- profuse salivation
- lacrimation
- visula disturbances
- bronchospasm
- diarrhea
- bradycardia
Atropine (atropen) drug class and mech of action
- anticholinergic muscarinic antagonist
- Competes to cause blockage of muscarinic receptors, no effect itself but prevents activation of muscarinic receptor by endogenous Ach and at high doses nicotinic receptors as well
Atropine (atropen) dosage and action
- low doses decrease secretion of salivary, sweat, and bronchial glands
- moderate doses increase heart rate and mydriasis
- higher doses urinary tract interfere with voiding and decrease intestine tone
- high doses in stomach causes decreased acid secretion
Atropine (atropen) therapuetic uses (4)
- preanasthetic meds
- opthalmic inducing mydriasis and parlysis of ciliary muscle
- can accelerate heart rate in bradycardia
- intestinal hypermotility reducing frequency of bowel movements and abdominal cramps
Atropine (atropen) ADR’s (4)
- dry mouth
- blurred vision and photophobia (paralysis of ciliary muscle focuses for far vision)
- elevation of intraocular pressure
- urinary retention
Scopolamine (hysoscine HBr) function
Muscarinic atnagonist like atropine but produces CNS sedation opposed to excitement and suppresses emesis and motion sickness
Neostigmine (prostigmin) absorption
contains positive charge, cannot cross BBB, GI tract, or placenta and must be administered high dose oral or by injection
Neostigmine (prostigmin) mech of action
Binds of AchE but rxn takes place extremely slowly tying up AchE and thus leaving Ach levels higher
This allows for identical muscarinic responses compared to the muscarinic agonists
Depolarizing nerumoscular blockade
Refers to when excessive amounts of Ach often from taking blocking agents such as Neostigmine (prostigmin) reducing force of contraction and producing paralysis of respiratory areas
Neostigmine (prostigmin) therapeutic use and mech of treatment
- myasthenia gravis
- prevents inactivation of Ach thereby intensifying effect of Ach at motor end plates, provides symptomatic relief with small dosage titrated upward until optimal level of muscle functioning has been produced
Neostigmine (prostigmin ADR’s (3)
- excess salivation
- increased gastric secretion
- miosis
Cholinergic crisis
Excessive activity of acetycholine causing respiratoyr suppression and
Treatment of cholinergic crisis (2)
- IV atropine
- mechanical ventilation
Physostigmine therapeutic uses (2)
- treatment of muscarinic antagonist poisoning
- glaucoma
3 common cholinesterase inhibitors used in alzheimer’s disease
- donepezil
- rivastigmine
- galantamine
Myasthenia gravis pathophys
disease characterized by muscle weakness and predisposition to rapid fatigue, common see difficulty swallowing, ptosis, and severe trouble breathing due to paralysis of respiratory muscles due to autoimmune antibodies against nicotinic II receptors on skeletal muscle, results in muscle weakness
Myasthenia crisis
-patient may experience if inadequately medicated, characterized by extreme weakness caused by insufficient ach at the NMJ and will lead to death by paralysis of respiratory muscles unless cholinesterase inhibitor used
Cholinergic crisis
Overdosage of cholinesterase inhibitor characterized by extreme weakness or frank paralysis, accompanied by signs of muscarinic stimulation and treated with respiratory support plus atropine
Determining cholinergic from myasthenia criss
- History of meds can provide diff diagnosis
- If inadequate, use ultra short acting cholinesterase agent and if symptoms alleviated then myasthenic, if intesnivides then cholinergic
