NJM and local anesthetics Flashcards
What are the non-depolaring NMJ blockers?
Atracurium, mivacurium, pancuronium, rocuronium
What is the depolaring NMJ blocker?
Succinylcholine
What are the local anesthetic Amides?
bupivacaine, lidocaine, ropivacaine, articaine
What are the local anesthetic Esters?
Benzocaine, cocaine hydrochloride
Explain some of the properties of NMJ blockers.
- cause complete relaxation of skeletal muscle
- do not pass BBB, no CNS effects
- First muscles blocked are small rapid moving, then limb/trunk, then intercostal, finally diaphragm.
This drug is used in treatment of malignant hyperthermia and long-term control of muscle spasms.
Dantrolene
Explain the properties of the non-depolarizing NMJ blockers
- not metabolized by AchE
- Competitive inhibition of Ach
- Reversed by physostigmine/neostigmine
The NMJ blockers that end in “curium” have what properties?
- Histamine release
2. Few vagal/ganglionic blocking effects
The NMJ blockers that end in “curonium” have what properties?
- Block ganglionic resulting in tachycardia
Rocuronium has little histamine release or tachycardia
This drug is metabolized by plasma cholinesterase causing the short duration.
Mivacurium
This drug has rapid onset, intermediate duration and is used to rapidly relax laryngeal and jaw muscles for tracheal intubation.
Rocuronium
This drug undergoes Hofmann reaction that is temperature and pH dependent.
Atracurium
Useful for patients with liver or renal failure
This drug has a long duration and is the 2nd drug used in lethal injection protocol.
Pancuronium
This drug is used for very short procedures such as intubation.
Succinylcholine
This drug causes initial fasciculations in the chest and abdomen. The minor twitching occur immediately.
Succinylcholine
This drug alters the electro-chemical driving force by causing what?
Succinylcholine.
Excessive opening of nicotinic Ach receptors
What are the 2 phases of action of succinylcholine?
phase 1: fast onset, single dose, neostigmine augments blocking action.
Phase 2: slow onset,after prolonged infusion or 10X dose, neostigmine antagonizes.
What are the 3 parts of all local anesthetics?
- lipophilic domain allow entry into neuronal axon.
- intermediate chain; amides - liver metabolized. Esters - blood metabolized.
- hydrophilic N terminal for inhibitory Na action.
An acidic environment will charge LA, can they enter neurons?
No, must be uncharged to enter neurons.
Charged once inside to cause Na block.
What is the rule for channels and local anesthetics?
More active channels, greater inhibition by LA
How does axon size affect blockade?
Small axons are first to be blocked. (C fibers)
Large axons blocked last. (motor neurons)
What produces surface anesthesia?
topical
What produces field block anesthesia?
subcutaneous
What produces nerve block anesthesia?
Peripheral nerves or plexus
What produces spinal block?
Cerebral spinal in subarachnoid space
What produces an epidural block?
Space within vertebral canal
What is limited and what is not limited to injection sites?
Limited - spinal
Not limited - epidural
This drug can decrease the rate of absorption and prolong anesthesia via vasoconstriction?
epinephrine
Where should vasocontrictors not be co-adminstered with LA?
in peripheral sites due to loss of blood supply
What side effects in the CNS occur in low concentrations?
sleepiness, dizziness, restlessnesss
Lidocaine can produce euphoria
What side effects in the CNS occur in high concentrations?
nystagmus, shivering, respiratory failure, tremor, restlessness
This drug is more cardiotoxic and can cause arrhythmias and hypotension.
Bupivacaine
A high dose of what drug can cause conversion of hemoglobin to methemoglobin?
benzocaine
This is the most widely used LA?
lidocaine
This is used for infiltration, nerve block, spinal, epidural. and useful for analgesia during labor.
Bupivacaine
This is a long acting, pure enantiomer used for procedures where motor block is undesirable (Labor)?
Ropivacaine
This drug is the choice of dentists, it is metabolized by plasma carboxyesterase.
Articaine
This drug is used topically for surface anesthesia.
Benzocaine
This drug is used topically and only with inherent vasoconstrictive properties.
Cocaine hydrochloride
Co-administration with epinephrine is unnecessary with?
Cocaine hydrochloride
This drug has a very rapid time to onset and very short duration.
Succinylcholine.
