Neuromuscular and ganglionic blockers Flashcards
Ganglionic blockers block which reflexes? (2)
Baroreceptor
Pupillary
What are ganglionic blockers?
Nicotinic receptor antagonists
What is Trimethaphan used for?
Hypotension for surgery
What is Mecamylamine used for? (3)
Tourette’s
Smoking Cessation
Severe hypertension
Majority of vascular smooth muscle tone is what?
SANS more than PANS
Majority in rest of ANS is what system?
PANS more than SANS
What is Train of Four impulse?
Response of 4th twitch relative to first
What does Train of Four ratio of 0.25 mean?
75% of receptors blocked, but still near full muscle responses.
What ratio is needed before extubation?
Greater than 0.7
What ratio is classified as full clinical recovery?
0.9
At what point is the patient properly sedated?
When only 1-2 twitches are seen during a neuromuscular blockage
Sequence of muscle paralysis by curare/neuromuscular blocker OD?
Eye -> Speech -> Fingers -> Toes -> Limbs -> Intercostals -> Diaphragm
What disease is similar to curare paralysis?
Guillain-Barre Syndrome
Characteristics of Succinylcholine? (2)
Short duration 5-10 minutes
Fast onset
What metabolizes Succinylcholine?
Butyrylcholinesterase
What do you use Succinylcholine for? (3)
Trauma care
Intubation
Electro-convulsant therapy
When do you want to avoid Succinylcholine?
Hyperkalemia, due to risk of cardiac arrest
How does the depolarizing neuromuscular blocker Succinylcholine work?
It is an agonist which means it bind and depolarizes which due to persistence makes the muscle fiber resistant to further stimulation by Ach.
How does the non-depolarizing (curare-like) neuromuscular blocker work?
It is a nicotinic acetylcholine receptor antagonist
Benefits of Pancuronium? (3)
Long duration (greater than 180 minutes) Easily reversible Widely used
What is neostigmine?
Reversible acetylcholinesterase inhibitor
Where is acetylcholinesterase located?
In the synapses
Where is Plasmacholinesterase located?
In plasma
What is a carbamate?
Acetylcholinesterase inhibitor
Characterisitics of Carbamates? (4)
Quaternary or tertiary amine group
Temporary covalent modification to AChE
Reversible
Dissociates in 0.5-0.8 hours
Main difference between physostigmine and neo/pyridostygmine?
Physostigmine enters CNS while Neo/Pyridostygmine is peripherally restricted
Pyrido word root means?
Orally available, so Pyrido can be taken orally for fewer side effects and longer duration
Organophosphates irreversible or reversible acetylcholinesterase inhibitors?
Irreversible
How long do Organophosphates last?
Longer than a week
What are organophosphates used to treat on occasion?
Glaucoma
What else irreversibly binds to acetylcholinesterase? (2)
Nerve Gas
Insecticides
What is antidote for Acetylcholinesterase inhibitor poisoning?
Pralidoxime Chloride (2-PAM)
When is Pralidoxime Chloride antidote most effective?
Within a few hours of exposure
What do you give for symptoms of Acetylcholinesterase inhibitor poisoning?
Atropine due to fast acting nature
Effect of Pralidoxime Chloride on organophosphate?
Organophosphate bond to AchE is broken and Acetylcholinesterase is regenerated
Mnemonic for symptoms of Acetylcholinesterase inhibitor poisoning?
DUMBBELSS D: Diarrhea U: Urination M: Miosis B: Branchospasms B: Bradycardia E: Excitation of skeletal muscle and CNS L: Lacrimation S: Sweating S: Salivation
Who is Acetylcholinesterase inhibitor poisoning most common in?
Farmers
What quaternary ammonium alcohol is used for diagnosis of myasthenia gravis?
Edrophonium (Tensilon)
What happens in Myasthenia Gravis?
Antibodies block Nicotinic acetylcholine receptors at the postsynaptic neuromuscular junction
What does Myasthenia Gravis cause?
Muscle weakness
What does Edrophonium test differentiate between?
Myasthenia Gravis and Lambert Eaton
How does the Edrophonium differ between the two?
In MG exercise worsens muscle strength and Edro improves muscle strength while in Lambert Eaton exercise improves muscle strength while Edro has no effect on muscle strength
How do you treat MG?
Neostigmine/pyridostigmine
Effect of Edrophonium between cholinergic crisis and myasthenia crisis?
In CC Edro has no effect, maybe small muscle decrease
In MG Edro improves muscle strength
When do you want to avoid the use of parasympathomimetic drugs? (5)
Asthma/COPD Coronary deficiency Peptic Ulcer Obstruction of urinary or GI tract Epilepsy
Cholinergic centers in the CNS? (2)
Nucleus Basalis of Meynert/medial septal nuclei (basal forebrain) Mesopontine tegmentum (brain stem)
Adrenergic centers in brain (1)?
Locus Coeruleus
What does Locus Coeruleus produce?
Norepinephrine
Alzheimer’s disease is due to deficits in what?
Cholinergic
Most common cause of dementia after age 50?
Alzheimers
What brain changes are there in Alzheimer’s?
Widening of sulk and thinning of gyri
What malfunction causes alzheimer’s?
Improper processing of b-amyloid precursor protein (b-APP) leads to toxic form (b-A42) that promotes apoptosis
What pathologies will you see in Alzheimer’s? (2)
B-amyloid plaques
Neurofibrillary tangles
What do you treat alzheimer’s with?
ACHE inhibitors
What specific drugs can you give for Alzheimer’s?
Donepezil
Rivastigmine
Galanthamine
What is Donepezil?
ACHE inhibitor
Reversible
Enhances cognitive ability
Doesn’t slow disease
What is Rivastigmine?
Reversible
carbamate ACHE inhibitor
Loses effectiveness as disease progresses
Replaced by Eptastigmine
What is Galanthamine?
Reversible competitive ACHE inhibitor
Nicotinic receptor agonist
use with Inhibitors of P450 enzymes (increases bioavailability)
