Pharm Ch. 20 Cholinergic Drugs

what is a cholinergic drug

a drug that stimulates the parasympathetic nervous system

what is the PSNS

the opposing system to the SNS

what do cholinergic drugs mimic the effect of

they mimic the effects of the PSNS neurotransmitter acetylcholine

what are the 2 types of cholinergic receptors and what are they determined by

nicotinic and muscarinic receptors and determined by location and action once stimulated

what are nicotinic receptors

located in ganglia of both the PNS and SNS; stimulated by the alkaloid nicotine

what are muscarinic receptors

located postsynaptically in the effector organs if the PNS (smooth muscle, cardiac muscle, glands); stimulated by the alkaloid muscarine 

what is the direct mechanism of action for cholinergic drugs

bind to cholinergic receptors activating them; mimic the effects of acetylcholine

what is the indirect mechanism of action of cholinergic agonists

inhibit the enzyme acetylcholinesterase, which breaks down ACh and results in more ACh available at the receptors; cholinesterase inhibitors

what are reversible indirect acting cholinergic drugs

bind to cholinesterase for a short period of time

what are irreversible indirect acting cholinergic drugs

bind to cholinesterase for a long time; bind to cholinesterase and form a permanent covalent bond; body must make new cholinesterase to break these bonds

when are cholinergic drug effects seen

when the PSNS is stimulated

what happens after cholinergic drugs bind 

the permeability of the cell changes allowing flow of calcium and sodium into the cells resulting in depolarization of cell membrane and stimulation of the effector organ

what kind of system is the PNS

rest and digest

what type of system is the SNS

flight or fight

what happens when cholinergic drugs stimulate the intestine and bladder

increased gastric secretions; increased gastrointestinal motility; increased urinary frequency

what happens when cholinergic drugs stimulate pupils

constriction (miosis)

reduced intraocular pressure

what are cardiovascular effects of cholinergic drugs

decreased heart rate and vasodilation

what are respiratory effects of cholinergic drugs

bronchial constriction and narrowed airways

at recommended doses what do cholinergic primarily effect/ what are desired effects

(stimulation of) muscarinic receptors

at high doses what do cholinergic stimulate

nicotinic receptors; which give off undesirable effects

what are direct acting drug indications 

reduce intraocular pressure; useful for glaucoma and intraocular surgery (echothiopate, carbachol, pilocarpine); topical application bc of poor oral absorption

what des the direct acting drug bethanechol do (indications)

increases tone and motility of bladder; relaxes sphincters in bladder; helpful for postsurgical atony of the bladder; oral

what does the direct acting drug cevimeline do (indications)

used to treat excessively dry mouth (xerostomia) resulting from a disorder known as Sjogren’s syndrome

what does the direct acting drug succinylcholine do (indications)

used as a neuromuscular blocker in general anesthesia

what do indirect acting drugs do (indications)

-increase ACh concentrations at the receptor sites, which leads to stimulations of the effector cells

-cause skeletal muscle contractions

-used for diagnosis and treatment of myasthenia gravis 

what do indirect acting drugs reverse (indications)

-neuromuscular blocking drugs

-reverse anticholinergic poisoning (antidote) i.e. physostigmine, pyridostigmine, and neostigmine

what do the indirect acting anticholinesterase drugs do 

used for treatments of mild to moderate alzheimer’s (donepezil/aricept, galantamine/razadyne, and rivastigmine/exelon)

what is Memantine (Namenda)

not a cholinergic drug; also used to treat alzheimer’s

what are cholinergic drug contradictions

known drug allergy, GI or GU obstruction, bradycardia, defects in cardiac impulse conduction, hyperthyroidism, epilepsy, hypotension, COPD, Parkinson’s

what does it mean when there is an adverse effect with cholinergic drugs

there is overstimulation in the PSNS

what are cholinergic drug adverse effects with the cardiovascular system

bradycardia, hypotension, syncope, conduction abnormalities (AV block and cardiac arrest)

what are cholinergic drug adverse effects in the CNS

headache, dizziness, convulsions, ataxia

what are cholinergic drug adverse effects in the GI system

abdominal cramps, increased secretions, nausea, vomiting

what are cholinergic drug adverse effects in the respiratory system

increased bronchial secretions, bronchospasms

what are cholinergic drug adverse effects in general

lacrimation, sweating, salivation, miosis

what happens in a cholinergic crisis (toxic/overdose)

circulatory system collapses, hypotension, bloody diarrhea, shock, and cardiac arrest

what does SLUDGE stand for

salivation, lacrimation, urinary incontinence, diarrhea, GI cramps, and emesis

what are early signs of toxicity/overdose

abdominal cramps, salivation, flushing of the skin, nausea and vomiting, transient syncope, transient complete heart block, dyspnea, and orthostatic hypotension

what is the early treatment in a cholinergic crisis

atropine a cholinergic antagonist

what is the treatment of severe cardiovascular reactions or bronchocontriction

epinephrine an adrenergic agonist

how do cholinergic drugs interact with anticholinergics, antihistamines, and sympathomimetics

antagonize cholinergic drugs, resulting in decreased responses

how do other cholinergic drugs interact

they have additive effects

what is Bethanechol (Urecholine)

a direct acting cholinergic agonist

what is Bethanechol uses

treatment of acute postoperative and postpartum nonobstructive urinary retention and for the management of urinary retention associated with neurogenic atony of the bladder

what are Bethanechol’s contraindictions

known drug allergy, hyperthyroidism, peptic ulcer, active bronchial, asthma cardiac disease or coronary artery disease, epilepsy, and parkinsonism

what is Bethanechol’s adverse effects

syncope, hypotension with reflex tachycardia, headache, seizure, GI upset, and asthma attacks

what is Bethanechol’s interactions

acetylcholinesterase inhibitors i.e. indirect acting cholinergic

what is Donepezil

Cholinesterase inhibitor that works centrally in the brain to increase levels of ACh by inhibiting acetylcholinesterase

how is Donepezil used

in treatment of mild to moderate Alzheimer’s disease

what are similar cholinesterase inhibitors with Donepezil

galantamine and rivastigmine

what are contraindications with Donepezil

known drug allergy

what are adverse effects with Donepezil

GI upset, drowsiness, dizziness, insomnia, and muscle cramps