Neuromuscular blocking drugs

Question 1

The main site of action of neuromuscular blocking agents (muscle relaxants) is on the?

Answer 1

Nicotinic cholinergic receptors at the endplate of muscles

Question 2

Is a blocking agent that produces depolarization

at the endplate and binds to extrajunctional receptors..

Answer 2

Succinylcholine

Question 3

The TOF fade is difficult to evaluate manually or visually during recovery when TOF ratio is >

Answer 3

0.4

Question 4

When using mivacurium, reversal with anticholinesterases should be attempted only when all four twitches in response to TOF stimulation are visible at what muscle?

Answer 4

Adductor pollicis muscle

Question 5

Most widely used measurement for awareness

Answer 5

Bispectral index

Question 6

Threshold for complete neuromuscular recovery is a train-of-four (TOF) ratio of?

Answer 6

0.9

Question 7

The terminal portion of the axon is a specialized structure, designed for the production and release of acetylcholine.

Answer 7

Synapse

Question 8

The synapse is separated from the endplate of the muscle fiber by a narrow gap, called?

Which is approximatelywhich is approximately how wide (nm or um)

Answer 8

Synaptic cleft

50 nm or 0.05 um

Question 9

Under resting conditions, the electrical potential of the inside of a nerve cell is negative with respect to the outside which is how much mV?

Answer 9

-90 mV

Question 10

Acetycholine is released in?

Answer 10

Quanta or packets

Question 11

Acetylcholine is synthesized from choline and acetate and packaged into __ vesicles

When an action potential invades the nerve terminal, approximately ____ quanta are released, unloading approximately ____ acetylcholine molecules?

Answer 11

45 nm

200 to 400 quanta
1 to 4 million

Question 12

Each vesicle contains ____ acetylcholine molecules.

Answer 12

5,000 to 10,000

Question 13

Some of these vesicles cluster near the cell membrane opposite the crests of the junctional folds of the endplate, in areas called?

Answer 13

active zones

Question 14

Neuromuscular blocking agents functions (3)

Answer 14

1. Improve conditions for tracheal intubation
2. Provide immobility for surgery
3. Facilitate mechanical ventilation

Question 15

Suggamadex is a selective binding agent for NMBAs such as (2)

Answer 15

1. Rocuronium

2. Vecuronium

Question 16

The main site of action of NMBAs is on the?

Answer 16

Nicotinic cholinergic receptor

Question 17

Is a specialized portion of the membrane of the muscle fiber where nicotinic acetylcholine receptors are concentrated

Answer 17

Endplate (especially at the crest of the folds)

Question 18

Calcium, which enters the nerve terminal through channels that open in response to depolarization, is required for ____________ and ________.

Answer 18

Vesicle fusion and release

Question 19

Each impulse releases ___% to ____ % of the 75,000

to 100,000 vesicles in the nerve terminal.

Answer 19

0.2% to 0.5%

Question 20

The receptors at the endplate are of the nicotinic cholinergic type.

They are members of the class of _____ ion channels, to which glycine, 5HT3, and GABA receptors belong.

Answer 20

Cysloop ligand gated

Question 21

The nicotinic subtype present at the neuromuscular junction is made up of two identical subunits, designated _, and three others, called _, _, and _.

Answer 21

a, and three others, called B, S, and E

Question 22

The muscle action potential has a duration of ___ ms?

Answer 22

5 to 15

Question 23

Early in development, receptors are slightly different from those found at the adult endplate: They have a ___ subunit instead of an E subunit.

Answer 23

y subunit (fetal receptors) instead of an E subunit

Question 24

As maturation continues, the y subunit is substituted by an E subunit, which is characteristic of the adult type, junctional receptor. In humans, the switch occurs in the ___ trimester of pregnancy.

Answer 24

third

Question 25

Is determined by constructing dose-response curves, which describe the relationship between twitch depression and dose

Answer 25

Potency

Question 26

``` Or time to maximum blockade, can be shortened if the dose is increased. When two or more drugs are compared, it is meaningful to compare only equipotent doses and usually clinically relevant doses (2 × ED95) are considered. ```

Answer 26

Onset time

Question 27

Is the time from injection of the neuromuscular | blocking agent to return of 25% twitch height (compared with control).

Answer 27

Duration time

Question 28

Is the time interval between 25% and 75% twitch height.

Answer 28

Recovery time

Question 29

After 30 to 60 minutes of administration of succinylcholine, tetanic fade becomes apparent. However neostigmine or edrophonium can antagonize this block which is termed as?

Answer 29

nondepolarizing, dual, or phase II block

Question 30

2 effective defasciculating agents for succinylcholine

Answer 30

1. Rocuronium (0.03 - 0.04 mg/kg) | 2. Atracurium (0.02 mg/kg)

Question 31

Intraocular pressure increases by ___ to ___ mmHg after succinylcholine administration

Answer 31

5 to 15

Question 32

Serum potassium increases by ___ mEq/L after succinylcholine administration

Answer 32

0.5 mEq/L

Question 33

Plasma cholinesterase activity is reduced by what 2 drugs?

Answer 33

Neostigmine and pyridostigmine

Question 34

Cholinesterase gene is located in?

Answer 34

chromosome 3 at q26

Question 35

Nondepolarizing neuromuscular blocking drugs bind to the ______receptor in a competitive fashion, by binding to one of the ___ subunits of the receptor

Answer 35

postsynaptic | a

Question 36

The volume of distribution of non-depolarizing agents is equivalent o the ECF volume which is about?

Answer 36

0.2 to 0.4 L/kg

Question 37

Is determined by the time required for drug concentrations at the site of action to reach a critical level, usually that corresponding to 100% block

Answer 37

Onset time This delay reflects the time required for drug transfer between plasma and neuromuscular junction and is represented quantitatively by a rate constant (keo). This rate constant corresponds to half-times of 5 to 10 minutes for most nondepolarizing drugs and is determined by all the factors that modify access of the drug to, and its removal from, the neuromuscular junction. These include cardiac output, distance of the muscle from the heart, and muscle blood flow. Thus, neuromuscular blockade usually occurs sooner at well-perfused centrally located muscles (diaphragm or vocal cords) than at peripheral locations (hand or foot).

Question 38

Is determined by the time required for drug concentrations at the site of action to decrease below a certain level, usually corresponding to 25% first twitch blockade.

Answer 38

Duration of action

Question 39

A nonenzymatic degradation with a rate that increases as temperature and/or pH increases.

Answer 39

Hoffman elimination

Question 40

The enzymes involved in the metabolic pathway of atracurium involves? The same in the degradation of what two drugs?

Answer 40

Tissue esterases Esmolol and ramifentanil

Question 41

The end products of the degradation of atracurium are:

Answer 41

laudanosine (seizures) and acrylate fragments

Question 42

Main degradation pathway of gantacurium?

Answer 42

cysteine

Question 43

Most potent metabolite of vecuronium

Answer 43

3-OH vecuronium