Mod 5 Adrenergic drugs Flashcards
Cholinergic Drugs: Definition
Drugs that stimulate the parasympathetic
nervous system (PSNS)
Th PSNS is the opposing system to the SNS
Cholinergic Drugs: Definition
cont’d
Also known as cholinergic agonists or
parasympathomimetics
Mimic the effects of the PSNS
neurotransmitter: acetylcholine (Ach)
Cholinergic Receptors
Two types, determined by: Location Action once stimulated Nicotinic receptors Muscarinic receptors
Nicotinic Receptors
Located in the ganglia of both the PSNS and SNS Named “nicotinic” because they can be Namedae nicotinic nicotinic because because theye can can bee stimulated by the alkaloid nicotine
Muscarinic Receptors
Located postsynaptically in the effector
organs of the PSNS
Smooth muscle
Cardiac muscle
Glands
Named “muscarinic” because they can be stimulated by the alkaloid muscarine
Mechanism of Action
Directrec–acting cholinergic agonists acting cholinergic agonists
Bind to cholinergic receptors, activating them
Indirect–acting cholinergic agonists
Inhibit the enzyme acetylcholinesterase, which breaks down Ach
Results in more Ach available at the receptors
Indirect Indirect–Acting (Cholinesterase Acting (Cholinesterase Inhibitors)
Reversible Bind to cholinesterase for a period of minutes to hours Irreversible Bind to cholinesterase and form a permanent covalent bond The body must make new cholinesterase
Drug Effects
Effects seen when the PSNS is stimulated
The PSNS is the “rest and digest” system
Drug Effects (cont’d)
“SLUDGE” Salivation Lacrimation Urination Diarrhea/defecation Gastrointestinal cramps Emesis
Drug Effects (cont’d)
Stimulate intestine and bladder Increased gastric secretions Increased gastrointestinal motility Increased urinary frequency Stimulate pupils Constriction (miosis) Reduced intraocular pressure Increased salivation and sweating
Drug Effects (cont’d)
Cardiovascular effects Decreased heart rate Vasodilation Respiratory effects Bronchial constriction, narrowed airways
Drug Effects (cont’d)
At recommended doses, the cholinergics
primarily affect the muscarinic receptors
At high doses, cholinergics stimulate the
nicotinic receptors
Drug Effects (cont’d)
Desired effects: from muscarinic receptor
stimulation
Many undesirable effects are due to
Manyan undesirable undesirable effects effects are are dueue too
stimulation of the nicotinic receptors
Indications
Directrec--acting drugs acting drugs Reduce intraocular pressure Useful for glaucoma and intraocular surgery AAcecettyyllcchhoolilinene • Carbachol • Pilocarpine Topical application because of poor oral absorption
Indications (cont’d)
Directrec–acting drug acting drug—bethanechol bethanechol
Increases tone and motility of bladder and GI tract
Relaxes sphincters in bladder and GI tract allowing
Relaxes Relaxes sphincters sphincters inn bladder bladder and an GI tractrac, , allowing allowing
them to empty
Helpful for postsurgical atony of the bladder
and GI tract
