Anticholinergics Flashcards
What to anticholinergics do to muscarinic and nicotinic receptors?
- antagonize effects of Ach at muscarinic receptors
- heart, salivary glands, GI and GU tracts
- exert little or no effect at nicotinic receptors
- NM junction, autonomic ganglia
Which are naturally occurring tertiary amines that are ionized, but lipophillic enough to cross the BBB?
Atropine and Scopalamine
Which anticholinergic drug does NOT cross the BBB?
GLYCOPYRROLATE
How does an anticholinergic drug fit inthe muscarinic receptors?
The cation portion can fit into the muscarinic receptor
Anticholinergics are competitive antagonists. What do they do exactly?
- reversibly bind with muscarinic receptor, preventing Ach from binding
- do not alter membrane
- do not prevent release of Ach or alter it
- increasing Ach can overcome effect of the drug
- small doses may actually stimulate or receptors and decrease HR
What are the 5 subtypes of muscarinic receptors and what are their specific functions?
M1:
- CNS and stomach—> H+ secretion
M2:
- lungs and heart—> Bradycardia
M3:
- CNS, airway, smooth muscle, glandular tissue—> salivation, bronchodilation
M4 and M5: weak CNS effect (not significant)
How do the muscarinic cholinergic receptors vary in sensitivity?
M3
What is the duration for atropine and glycopyrrolate?
IV duration = 30-60 min
May need to redose
What are uses for anticholinergics?
- pre-op meds: sedation, antisialagogue, prevent vagal reflexes
- treat reflex mediated bradycardia
- combined with anticholinesterase drugs
- bronchodilation
- prevent motion induced nausea
How do anticholinergics contribute to sedation?
- Assoc. with restlessness and somnolence
- delayed awakening, esp in elderly
- inhaled anesth. Potentiate CNS effects
- reverse with physostigmine
How does scopalamine compare to atropine in regards to sedation?
Scopalamine is 100xs more potent than atropine to decrease activity of reticular activating system (RAS)
* amnestic
Atropine: increased incidence of memory deficits compared to glycopyrrolate, delayed arrousal in 1st 30 min after end of anesthesia when reversed with atropine/neo
How do the anticholinergics differ in the anti-sialagogue effect?
- scop. 3xs more potent than atropine
- glycopyrrolate 2xs more potent than atropine and longer duration
Scop > glycopyrrolate > atropine
How are anticholinergics usually used to prevent vagal reflexes?
- frequently used in pediatrics <1 year to blunt vagal reflex associate with laryngoscopy for intubation
- usually give IV after mask induction
What is the drug of choice in bradycardia?
ATROPINE
Blocks effects of Ach on SA node
Most evident on young adults
(Scop and glycopyrrolate less effective at equivalent doses)
Anticholinergics prevent ______________________________ effects of AchE.
Parasympathomimetic
- combine with AchE to reverse NMB drugs
What is the bronchodilation (M3) effect due to?
Due to antagonism of Ach effects on airway smooth muscle
*** decreases airway resistance and increases dead space in asthma and chronic bronchitis (spirits and Atrovent)
How are anticholinergics used to prevent motion- induced nausea?
Transdermal scop patch: apply 4 hours prior to need
S/e: sedation, mydriasis, dry mouth, localized irritation
(Also used for hiccups, cold remedy, anti-gastric [H+] secretion, biliary and smooth muscle relaxant
What are s/s of anticholinergic OD?
Anti rest and digest
** CAN’T SEE, CAN’T PEE, CAN’T SPIT, CAN’T SHIT **
What is the treatment for anticholinergic OD?
Physostigmine—> May need repeat doses
What is Suggamadex for?
- reversal of amino-steroids (primarily vecuronium and rocuronium)
- Bind contents of Roc and take it away
- hydrophobic center, hydrophilic exterior
What is the t 1/2 of Suggamadex?
2 hours
Not protein bound
What area side effects of Suggamadex?
- anaphylaxis in 0.3%
- bradycardia
- > PTT/PT/INR up to 1 hour
- > 10% N/V, pain,hypotension, HA
- not studied yet in renal pts
What is the most common cause of PONV?
Neostigmine
After Suggamadex is used what do you need to counsel your pt to do?
Use second form a birth control for 1 week d/t decreased efficacy of oral contraceptives
