18 Questions
What is the primary purpose of Neuromuscular Blockers?
To interfere with transmission at the neuromuscular end plate
Which type of muscle relaxants has the shortest duration of action?
Mivacurium
In what type of conditions are Spasmolytics used?
To reduce spasticity in neurologic conditions
Which medication doesn't require a muscarinic receptor antagonist for reversal of its effects?
Pancuronium
What is the main characteristic of Spasmolytics?
They reduce spasticity
What is the general route of administration for Neuromuscular Blockers?
Intravenous
What is the mechanism of action of Depolarizing Agents like Succinylcholine?
Attach to nicotinic receptors and act like acetylcholine
Which phase of the Neuromuscular Blockers effect involves continuous muscle contraction and spastic paralysis?
Phase I Block (Depolarization)
How is the toxicity of Non-Depolarizing Blockers best managed?
With Neostigmine & other Cholinesterase inhibitors
What are the clinical uses of Neuromuscular Blockers?
Control of convulsions
Which condition can Neuromuscular Blockers cause that may lead to cardiac arrest?
Hyperkalemia
What is the primary purpose of Spasmolytics?
Alleviate musculoskeletal pain and spasms
What is the mechanism of action of non-depolarizing blockers?
Prevents the binding of acetylcholine to nicotinic receptors, inhibiting muscle contraction
Which drug is known for causing 'spastic contraction'?
Curare Derivatives
What is the effect of an irreversible neuromuscular blocker on muscle contraction?
Leads to muscle weakness
How does a depolarizing blocker mimic acetylcholine?
It fakes itself as an acetylcholine molecule
What is the outcome of succinylcholine competing with a true NM agonist at the receptor level?
Development of fasciculation or muscle contraction
Which neuromuscular blocker has the fastest onset and shortest duration of action among the listed options?
Rapacuronium
Study Notes
Skeletal Muscle Relaxants
- Neuromuscular blockers are used during surgical procedures and in Intensive care units, often in combination with general anesthetics, local anesthetics, and analgesic agents like opioids to provide pain relief.
Neuromuscular Blockers
- Interfere with transmission at the neuromuscular end plate, lacking central nervous system activity, and are used primarily as adjuncts to general anesthesia.
- Adverse reactions include bronchoconstriction, hypotension, flushing, respiratory paralysis, and ganglionic blockade.
- Toxicity is best managed with neostigmine and other cholinesterase inhibitors like edrophonium and pyridostigmine.
Non-Depolarizing Blockers
- Mechanism of action involves binding to the nicotinic receptor, preventing acetylcholine binding, and inhibiting muscle contraction, resulting in flaccid paralysis.
- Examples include pancuronium, rapacuronium, and rocuronium.
Depolarizing Agents
- Succinylcholine attaches to the nicotinic receptor, depolarizing the junction, and causing transient twitching of the muscle (fasciculations).
- Two phases of action:
- Phase I Block (Depolarization): stimulation of the receptor, fasciculations, continuous muscle contraction, fatigue, and spastic paralysis.
- Phase II Block (Desensitization): the initial end-plate depolarization decreases, and the membrane becomes repolarized.
Clinical Uses of Neuromuscular Blockers
- Surgical relaxation for intra-abdominal and intra-thoracic procedures.
- Control of ventilation for severe bronchospasm, pneumonia, and COPD.
- Treatment of convulsions, epilepsy, and seizures.
Spasmolytics (Antispasmodics or Centrally Acting Muscle Relaxants)
- Used to alleviate musculoskeletal pain and spasms and to reduce spasticity in neurological conditions.
- Examples include mivacurium, which has the shortest duration of action among non-depolarizing muscle relaxants.
Test your knowledge on skeletal muscle relaxants including neuromuscular blockers and spasmolytics. Learn about their uses, mechanisms of action, and common side effects.
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