Pharma Flashcards
What are the two main classifications of skeletal muscle relaxants based on their site of action?
Central Muscle Relaxants and Peripheral Muscle Relaxants
Central Muscle Relaxants act on the CNS, while Peripheral Muscle Relaxants act on the motor nerve, neuromuscular junction, or skeletal muscle.
What is the mechanism of action of Diazepam as a muscle relaxant?
Agonist at Bzd receptors & ↑ GABA activity
Diazepam is classified as a central muscle relaxant.
Which muscle relaxant acts as an agonist at GABAB receptors?
Baclofen
Baclofen is used to reduce muscle spasticity.
What type of agonist is Tizanidine?
Central a2 agonist
Tizanidine is used for its muscle relaxant properties.
What is the function of Mephenesin?
Antidote to strychnine
Mephenesin is a central muscle relaxant.
Which muscle relaxants are commonly used in acute spastic conditions?
Methocarbamol, Cyclobenzaprine
These drugs are central muscle relaxants effective in acute situations.
What is the action of Dantrolene as a muscle relaxant?
Inhibits Ca release from SR
Dantrolene acts directly on muscle as a direct muscle relaxant.
Name a drug that inhibits acetylcholine (Ach) synthesis.
Hemicholinium or Triethylcholine
These drugs act peripherally on the nerve.
Which drug inhibits Ach storage?
Vesamicol
Vesamicol affects peripheral muscle relaxant action.
What are some methods that inhibit Ach release?
- Local anesthetics (e.g., procaine)
- Low Ca & Excess Mg
- Botulinum toxin
Botulinum toxin is used for various conditions, including muscle spasms and wrinkles.
What are the uses of Botulinum toxin?
- Eye muscle spasm (Blepharospasm & strabismus)
- Fascial wrinkles
- Achalasia of lower end of esophagus
- Overactive bladder
- Generalized spastic disorders (e.g., cerebral palsy & Multiple Sclerosis)
Botulinum toxin is administered via local injection.
What are the two types of neuromuscular blockers?
- Depolarizing NM-Blockers
- Competitive NM-Blockers
Both types block the action of Ach at Nm-receptors.
What is the effect of depolarizing NM-blockers?
Cause maintained depolarization of Nm-R leading to insensitivity and paralysis
Initial muscle twitches occur before paralysis.
Give an example of a depolarizing NM-blocker.
Succinylcholine or decamethonium
These drugs cause initial muscle twitches followed by paralysis.
What is the mechanism of action of competitive NM-blockers?
Compete with Ach for Nm-R leading to muscle paralysis without initial twitches
Examples include tubocurarine, atracurium, and rocuronium.
