ANS-5 Flashcards
Antimuscarinic agents are selective for ___, ___, and ___ receptors
M1, M2, M3
Antimuscarinic agents have little effect on ___
nicotinic receptors
Antimuscarinic agents are ____ antagonists
competitive
What is the problem with antimuscarinic agents such as Atropine?
lack of selectivity
Only ___ doses of Atropine can cause a partial block (M1) of the CNS
high
What are the 2 general classes of antimuscarinics?
tertiary amines and quarternary amines
antimuscarinic tertiary amines are mainly used on ___ and ___ applications
ocular, CNS
antimuscarinic quarternary amines are mainly used on ___ and ___ applications
GI tract, peripheral
What is this?
Atropine
What is this?
Anisotropine
T or F: Tertiary amines have good access to the CNS
True
Tertiary amines: Belladonna alkaloids (long acting)
Atropine and Scopolamine (Maldemar)
Tertiary amines: short acting derivatives
Homatropine and Tropicamide
Tertiary amines: Antiparkinson use
Benztropine (Cogentin) and Trihexyphenidyl (Artane)
Quaternary amines: Belladonna alkaloid derivatives
Ipratropium (Atrovent) and Tiotropium (Spiriva)
What is this?
Scopolamine (Maldemar)
Atropine and Scopolamine treat ___, ___, and ___
GI conditions, urinary conditions, and motion sickness
Compared to Atropine, Scopolamine has ___ CNS penetration
higher
Scopolamine is more ___philic than Atropine
lipo
Side effects of Scopolamine
dry mouth, blurred vision, and sedation
High doses: confusion and psychosis
Homatropine and Tropicamide are used in optical applications such as ___ and ___ because of the ___ duration of action
cycloplegia, mydriasis, short
Cycloplegia = paralysis of the ciliary muscle of the eye
Homatropine is ___ toxic; Tropicamide has a ___ duration of action
less, shorter
What is this?
Homatropine
What is this?
Tropicamide
Tertiary amines used for Parkinsons Disease have ___ activity
sedative
___ is used as an adjunct therapy with L-DOPA in PD patients (to achieve better balance between dopaminergic and cholinergic neurotransmission)
Benztropine (Cogentin)
What is this?
Benztropine (Cogentin)
Ipratropium (Atorvent) clinical use
M3 antagonist used for COPD treatment (blocks bronchoconstriction). Occasionally used for asthma. Enhances effect of B-adrenergic agoinst in COPD
Combivent/Duoneb is a combo of which two medications? (used to treat COPD)
ipratropium and albuterol
What is this?
Ipratropium
Quaternary amines for GI disorders
Glycopyrrolate amd Propantheline Bromide
Propantheline Bromide is not available in the US
___ is often used pre-op to reduce secretions
Glycopyrrolate
Why are quaternary amines good for GI?
positive charge makes it difficult to escape the gut
What is this?
Glycopyrrolate
Tolterodine (Detrol) is a antimuscarinic used for ____
overactive bladder (OAB)
What is this?
Propantheline Bromide
Tolterodine has no apparent selectivity for different muscarinic receptor subtypes; however therapeutically seems to act somewhat selectively on the ___ receptor
M3
What is this?
Tolterodine (Detrol)
Proposed advantages of newer M3 receptor-selective muscarinic antagonists used to treat OAB
Lower incidence of constipation and confusion
Examples of newer M3 drugs for OAB
Solifenacin (Vesicare) and Darifenacin (Enablex)
What is this?
Solifenacin (Vesicare)
What is this?
Darifenacin (Enablex)
Antimuscarinic Poisoning Treatment
- change medicine or decrease dose
- supportive care (sodium bicarbonate for QRS/arrhythmias, benzodiazepines for agitation/delirium)
- physostigmine (AChE inhibitor)
Neuromuscular blocking agents look like ___
ACh
What is this?
Succinylcholine
What is this?
Tubocurarine
Blocking the Nicotinic Receptor: What drug has a non-depolarizing blockade and acts as a “normal” antagonist?
Tubocurarine
Blocking the Nicotinic Receptor: What drug has a depolarizing blockade? (First activates, then blocks)
Succinylcholine
Depolarizing Blockade definition (nicotinic)
agonist remains bound to receptor. Persistent depolarization means fast Na+ channels cannot reset to active state.
Tubocurarine (Curare) mechansim
competitive antagonist for nicotinic receptors producing a non-depolarizing blockade
Tubocurarine (Curare)
clinical use
skeletal muscle relxation during anesthesia (useful for intubation)
Succinylcholine (Suxamethonium = SUX) mechanism
At first, acts as an nicotinic receptor agonist (initial depolarization). But it doesnt dissociate from the receptor and the presistent depolarization does not allow receptor to reset.
What metabolizes Succinylcholine?
Plasma Butyrylcholinesterase
slower than AChE breaking down ACh
T or F: Choline increases BP
True
Succinylcholine (SUX) clinical use:
skeletal muscle relaxation during anesthesia (useful for intubation and electro-convulsant therapy)
Problems with Succinylcholine (SUX)
muscle soreness (avoid in hyperkalemia - cardiac arrest), malignant hyperthermia, atypical cholinesterases (prolonged cholinesterases)
____ inhibits the release of ACh
Botulinum Toxin
Botulinum Toxin clinical use
uncontrolled muscle spasms (dystonias), cerebral palsy, ocular muscle spasms, anal fissures, excessive sweating (hyperhidrosis)
Problems with Botulinum Toxin
spreads from injection site
Hexamethonium mechanism
Antagonist at nicotinic receptors in autonomic ganglia thus blocking all SNS and PSNS activity
What was the original use of Hexamethonium and why is it no longer used?
hypertension, but no longer used due to adverse effects