Pharmacology of Skeletal Muscle Relaxants

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What is the primary action of skeletal muscle relaxants?

Inhibit nerve impulses

Stimulate muscle contraction

Decrease skeletal muscle tone (correct)

Increase skeletal muscle tone

What is the primary function of cholinesterase in the neuromuscular junction?

Release acetylcholine

Bind to NM receptors

Inactivate acetylcholine (correct)

Depolarize the motor end plate

Which type of skeletal muscle relaxant acts directly on skeletal muscle?

Nondepolarizing blockers

Depolarizing blockers

Dantrolene (correct)

Centrally acting drugs

What is the mode of action of competitive blockers?

Compete with acetylcholine for binding to receptors Signup and view all the answers

Which of the following is a centrally acting skeletal muscle relaxant?

Tizanidine Signup and view all the answers

What is the outcome of the binding of acetylcholine to NM receptors at the NMJ?

Depolarization and development of end-plate potential Signup and view all the answers

What is the purpose of using muscle relaxants in fracture of mandible?

To facilitate opening of the mouth for diagnosis and treatment Signup and view all the answers

What is succinylcholine used for during electroconvulsive therapy?

To prevent trauma due to convulsions Signup and view all the answers

What is the mechanism of action of botulinum toxin A?

It inhibits the release of ACh into the synaptic cleft Signup and view all the answers

What is the purpose of administering botulinum toxin A intradermally?

To produce an antiwrinkle effect in cosmetic procedures Signup and view all the answers

What is the purpose of prior atropine administration when reversing the action of competitive neuromuscular blockers?

To block the muscarinic effects of anticholinesterases Signup and view all the answers

What is the adverse effect of botulinum toxin A injection?

Pain at the site of injection Signup and view all the answers

What is the cause of sinus bradycardia?

Vagal stimulation Signup and view all the answers

What is the treatment for malignant hyperthermia?

Intravenous dantrolene, rapid cooling, inhalation of 100% oxygen and control of acidosis Signup and view all the answers

What is the mechanism of action of dantrolene in producing skeletal muscle relaxation?

Inhibiting depolarization-induced Ca2+ release from the sarcoplasmic reticulum Signup and view all the answers

What is the order of muscles affected by competitive blockers?

Extrinsic eye muscles, neck, face, hands, feet, limbs, trunk, respiratory Signup and view all the answers

What is the life-saving drug in malignant hyperthermia?

Dantrolene Signup and view all the answers

What is the effect of d-tubocurarine, mivacurium, and atracurium on histamine?

They cause histamine release Signup and view all the answers

What is the duration of action of succinylcholine?

3-8 minutes Signup and view all the answers

What is the purpose of washing the bath several times after adding succinylcholine in the frog rectus abdominis preparation?

To remove the effect of succinylcholine Signup and view all the answers

What is the main use of neuromuscular blockers?

As adjuvant to general anaesthesia for producing satisfactory skeletal muscle relaxation Signup and view all the answers

What is the condition of the basal contraction of the muscle in the frog rectus abdominis preparation?

Isometric Signup and view all the answers

What is the reason for muscle pain caused by succinylcholine?

Initial fasciculation Signup and view all the answers

What is the preferred neuromuscular blocker for short procedures?

Succinylcholine Signup and view all the answers

Which of the following skeletal muscle relaxants is contraindicated in patients with myasthenia gravis?

Any skeletal muscle relaxant Signup and view all the answers

What is the result of slow metabolism of succinylcholine in people with liver disease or atypical pseudocholinesterase?

Prolonged apnea Signup and view all the answers

What is the antidote for succinylcholine apnoea?

No antidote available Signup and view all the answers

What is the effect of aminoglycosides on neuromuscular blockers?

They potentiate the effect of neuromuscular blockers Signup and view all the answers

What is the mechanism of action of succinylcholine?

Depolarization of NM receptors Signup and view all the answers

What is the effect of succinylcholine on intragastric pressure?

Increased intragastric pressure Signup and view all the answers