Cholinergic Drugs Flashcards
Cholinergic drugs
AKA cholinergic agonists or Parasympathmimetics
- Stimulate the parasympathetic
- Mimic effects of the PSNS neurotransmitter acetylcholine (ACh)
What are the two difference types of cholinergic receptors?
Nicotinic and Muscarinic
Cholinergic Drug MOA
- mimic effect of acetylcholine
- Direct-acting cholinergic agonists
- Indirect-acting cholinergic agonists
- cholinesterase inhibitors
- inhibit the enzyme acetylcholinesterase, which breaks down ACh
- Results in more ACh available at the receptors
Reversible category
Indirect acting
-bind to cholinesterase for a short period of time
Irreversible
Indirect acting
- bind to cholinesterase for a long period of time
- Bind to cholinesterase and form a permanent covalent bond
- The body must make new cholinesterase to break these bonds
MOA and Drug Effect
Cholinergic Drugs
- after binding, permeability of the cell changes allowing flow of calcium and sodium into the cells
- results in depolarization of cell membrane and stimulation of the effector organ
- The PNS in the “rest and digest” system
- Stimulate intestine and bladder
- stimulate pupils-miosis
- increased salivation and sweating
- cardiovascular effects
- Respiratory effects
- SLUD
At recommended doses what does cholinergic primarily affect?
muscarininc
At high doses what does cholinergic stimulate
nicotinic
Direct-acting drugs
cholinergic
- reduce intraocular pressure
- useful for glaucoma and intraocular surgery
- Topical application because of poor oral absorption
Bethanechol
- increases tone and motility of bladder/GI tract
- relaxes sphincters in bladder/GI tract
- Helpful for postsurgical atony of the bladder/GI tract
Indirect- acting drugs
cholinergic
- increased ACh concentrations at the receptor sites, which leads to stimulation of the effector cells
- cause skeletal muscle contractions
- used for diagnosis and treatment of myashtenia gravis
- used to reverse neuromuscular blocking drugs
- used to reverse anticholinergic poisoning (antidote)
Indirect-acting anticholinesterase drugs
used for treatment of mild to moderate Alzheimers disease
-Donepezil, Galantamine, Rivastigmine, Memantine
Adverse Effects: cholinergic drugs
-Adverse effects are a result of overstimulation of PSNS
-Cardiovascular: brady, hypo, syncope, conduction abnormals
CNS: HA, dizzy, convulsions, ataxia
GI: abdomen cramps, secretions, N/V
Respiratory: bronchial secretions and spasms
Other: lacrimation, sweating, salivation, miosis
Toxicity for cholinergic
-circulatory collapse, hypotension, bloody diarrhea, shock, cardiac arrest
Early signs of toxicity
abdominal cramps, salivation, flushing of skin, N/V, transient syncope, transient complete heart block, dyspnea, Ortho hypotension
Treatment in early phase of Toxicity
atropine
Treatment of severe cardiovascular reactions or bronchoconstriction
epinephrine
Muscarinic Poisoning
- caused by certain mushrooms
- Overdose of direct-acting muscarinic agonists and indirect-acting cholinomimetics
- Symptoms-result from excessive activation of muscarinic receptors
- Treatment-Atropine
Bethanechol (Urecholine)
- Direct-acting cholinergic agonist
- Uses: acute postop and postpartum nonobstructive urinary retention and management of urinary retention associated with neurogenic atony of the bladder
- Contraindications: known drug allergy, hyperthyroidism, peptic ulcer, active bronchial asthma, cardiac disease or coronary artery disease, epilepsy, and parkinsonism
Donepezil (Aricept)
- cholinesterase inhibitor that works centrally in the brain to increase levels of ACh by inhibiting acetylcholinesterase
- used in the treatment of mild to moderate Alzheimers disease
- similar cholinesterase inhibitor include galantamine and rivastigmine
- Adverse effects: GI upset, drowsiness, dizziness, insomnia, muscle cramps. Cardiovascular effects may include brady, syncope, hypotension with refelx tachycardia, or HTN
- interacting drugs: anticholinergics and NSAIDS
Memantine (Namenda)
- not a cholinergic drug
- NMDA receptor antagonist
- used for treatment of Alzheimers disease
- improves cognitive function and quality of life
Neostigmine, Pyridostigmine, and Physostigmine
-used: reversing the effects of nondepolarizing neuromuscular blocking drugs; treating severe overdoses of tricyclic anttidepressants; and antidote after toxic exposure to nondrug anticholinergic agents, including those used in chemical warfare
Pyridostigmine (Mestinon)
- Indirect-acting cholinergic drugs that work to increase ACh by inhibiting acetylcholinesterase
- use: myasthenia gravis
Edrophonium (Tensilon)
indirect-acting cholinergic drug that is used to diagnose myasthenia gravis. It can also be used to differentiate between myasthenia gravis and cholinergic crisis
