neuromuscular blockers

Question 1

What is the mechanism of action of Suxamethonium?

Answer 1

Depolarising ACh agonist → persistent depolarisation → flaccid paralysis (Phase I → Phase II block)

Stimulates muscarinic receptors thus causing bradycardia, hypotension and salivation

Question 2

What are the contraindications for Suxamethonium?

Answer 2

Malignant hyperthermia history, Burns/trauma, Hyperkalaemia, Atypical cholinesterase

These conditions can lead to severe adverse reactions when using Suxamethonium.

Question 3

What drug interactions are associated with Suxamethonium?

Answer 3

Cholinesterase inhibitors, Aminoglycosides, Volatile anaesthetics

These interactions can prolong the neuromuscular block or increase the risk of malignant hyperthermia.

Question 4

What are the indications for Suxamethonium?

Answer 4

Rapid-onset muscle relaxation for intubation, Short surgical procedures

It is commonly used in emergency and surgical settings.

Question 5

What are the adverse effects of Suxamethonium?

Answer 5

Myalgia, hyperkalaemia, arrhythmias, ↑ IOP, malignant hyperthermia, histamine effects

Histamine effects can include bronchospasm among others.

Question 6

What is the mechanism of action of Atracurium?

Answer 6

Non-depolarising; competitive ACh antagonist

It works by blocking the action of acetylcholine at the neuromuscular junction.

Question 7

What are the contraindications for Atracurium?

Answer 7

Hypersensitivity, Asthma

Hypersensitivity can lead to severe allergic reactions.

Question 8

What are the indications for Atracurium?

Answer 8

Surgical muscle relaxation, Mechanical ventilation

Used in various surgical and critical care settings.

Question 9

What are the adverse effects of Atracurium?

Answer 9

Hypotension (histamine-related)

The release of histamine can lead to a drop in blood pressure.

Question 10

What is the mechanism of action of Mivacurium?

Answer 10

Non-depolarising; competitive ACh antagonist

Similar to Atracurium, it blocks acetylcholine at the neuromuscular junction.

Question 11

What are the contraindications for Mivacurium?

Answer 11

Pseudocholinesterase deficiency, Bronchospasm risk

Patients with these conditions may experience prolonged effects or severe reactions.

Question 12

What are the indications for Mivacurium?

Answer 12

Short-duration muscle relaxation

Often used in procedures requiring quick muscle relaxation.

Question 13

What are the adverse effects of Mivacurium?

Answer 13

Hypotension, bronchospasm, prolonged block in enzyme deficiency

Prolonged neuromuscular block can occur in patients with pseudocholinesterase deficiency.

Question 14

What is the mechanism of action of Rocuronium?

Answer 14

Non-depolarising; competitive ACh antagonist (no histamine release)

It provides muscle relaxation without the side effect of histamine release.

Question 15

What are the contraindications for Rocuronium?

Answer 15

Liver dysfunction, Hypersensitivity

These conditions can affect the metabolism and efficacy of the drug.

Question 16

What are the indications for Rocuronium?

Answer 16

Rapid sequence intubation, Intermediate to long surgical procedures

Its rapid onset makes it suitable for emergency intubations.

Question 17

What are the adverse effects of Rocuronium?

Answer 17

Anaphylaxis (rare), minimal histamine release

Although rare, anaphylaxis can occur in susceptible individuals.

Question 18

What is the mechanism of action of Dantrolene?

Answer 18

Blocks RYR1 receptor → ↓ Ca²⁺ release from SR → muscle relaxation direct acting

Dantrolene acts directly on muscle cells to reduce calcium release.

Question 19

What are the indications for Dantrolene?

Answer 19

Malignant hyperthermia, Muscle spasticity (neuronal origin)

It is primarily used in cases of severe muscle rigidity and hyperthermia.

Question 20

What are the adverse effects of Dantrolene?

Answer 20

Muscle weakness, sedation, hepatotoxicity

Chronic use can lead to liver damage.

Question 21

What is the mechanism of action of Diazepam?

Answer 21

Enhances GABAA receptor → hyperpolarisation → muscle relaxation

It acts as a central nervous system depressant.

Question 22

What are the indications for Diazepam?

Answer 22

Spasticity (any origin), Cerebral palsy, Tetanus, Reflex spasms

Effective for various muscle spasticity disorders.

Question 23

What are the adverse effects of Diazepam?

Answer 23

Sedation, high abuse potential

It can lead to dependence and withdrawal symptoms.

Question 24

What is the mechanism of action of Baclofen?

Answer 24

Enhances GABAB receptor → hyperpolarisation → muscle relaxation

It is specifically effective for spasticity.

Question 25

What are the indications for Baclofen?

Answer 25

multiple sclerosis, transverse myelitis, traumatic paraplegia and paraparesis), pain relief in trigeminal neuralgia ## Footnote Similar to Diazepam, it is used for various muscle spasticity disorders.

Question 26

What are the adverse effects of Baclofen?

Answer 26

Sedation, high abuse potential ## Footnote Caution is needed due to the risk of dependence.

Question 27

What is the mechanism of action of Cyclobenzaprine?

Answer 27

Centrally acting at brainstem; ↓ tonic somatic motor activity (TCA-like structure) ## Footnote It shares structural similarities with tricyclic antidepressants.

Question 28

What are the indications for Cyclobenzaprine?

Answer 28

Acute painful muscle spasm (peripheral origin) ## Footnote It is primarily used for short-term relief of muscle spasms.

Question 29

What are the adverse effects of Cyclobenzaprine?

Answer 29

Antimuscarinic: sedation, confusion, hallucinations, ↑ HR ## Footnote Its anticholinergic effects can lead to significant side effects.

Question 30

What is the mechanism of action of Orphenadrine?

Answer 30

Antimuscarinic + blocks glutamate receptors ## Footnote It helps alleviate muscle spasms by reducing excitatory neurotransmission.

Question 31

What are the contraindications for Orphenadrine?

Answer 31

Myasthenia gravis ## Footnote Its anticholinergic action can worsen muscle weakness in these patients.

Question 32

What are the indications for Orphenadrine?

Answer 32

Muscle spasm pain, Tremor/stiffness in Parkinsonism ## Footnote It is effective for various muscle-related disorders.

Question 33

What are the adverse effects of Orphenadrine?

Answer 33

Sedation, dry mouth, dizziness ## Footnote These effects are common with antimuscarinic medications.

Question 34

What is the mechanism of action of Gabapentin?

Answer 34

Centrally acting spasmolytic ## Footnote It modulates neurotransmitter release to reduce muscle spasticity.

Question 35

What are the indications for Gabapentin?

Answer 35

CNS-related muscle spasticity ## Footnote It is often used for neuropathic pain and spasticity.

Question 36

What is the mechanism of action of Pregabalin?

Answer 36

Not specified in document ## Footnote It is structurally related to Gabapentin and also used for neuropathic pain.