Muscle relaxants

Question 1

Many of CNS inhibitory drugs demonstrates weaker or

stronger muscle relaxant effect, E.g.

Answer 1

Phenotiazines < Opioids < Alpha2-agonists < Anaesthetics

Their effect is not always complete and sufficient regarding the special needs of surgery

Question 2

GUAIPHENESIN

- effects:

Answer 2

effective against convulsion caused by strychnine, tetanus
- It paralyses limb muscles, whilst respiratory muscles are generally unaffected.

• Secondary effect: expectorant

Question 3

Central muscle relaxnats:

Answer 3

• Guaiphenesin
• Baclophen
• Carisoprodol
• Methocarbamol

Question 4

Baclophen

- function

Answer 4

agonist at GABAB receptors in the brain and spinal cord,
resulting in hyperpolarization of neurons due to increased K+ ion conductance
- pain reduction

Question 5

Carisoprodol is available by itself or in combination with:

Answer 5

Aspirin and in one preparation along with codeine and caffeine as well

Question 6

PERIPHERAL MUSCLE RELAXANT DRUGS
(Neuromuscular Blocking Agents)
- 2 groups
- drugs

Answer 6

• Depolarizing agents act similarly to Ach. (succinylcholine)
• Nondepolarizing agents antagonise the ACh competively – cf. Competitive agents
  (curare)

Question 7

Succinylcholine chloride side effects:

Answer 7

• bradycardia (atropine can prevent),
• hyperkalaemia,
• increased intra-ocular and intragastric pressure,
• anaphylaxis,
• malignant hyperthermia in genetically predisposed subjects.
• Dogs, cattle, sheep sensitive; horses and pigs less
  so.

Question 8

Activity of succinylcholine is enhanced or potentiated by:

Answer 8

neostigmine and organophosphates (cholinesterase inhibitors), isoflurane.

Question 9

nondepolarizing - neuromuscular blocking agents

Answer 9

• Atracurium
• Cisatracurium
• Vecuronium

Question 10

Dunation of action of the different nondepolarizing- neuromuscular blocking agents

Answer 10

• Ultra-short duration:
  Gantacurium
• Short duration:
  Mivacurium • Chandonium
• Intermediate duration:
  Atracurium • Cisatracurium •
  Fazadinium • Rocuronium • Vecuronium
• Long duration:
  Doxacurium • Dimethyltubocurarine •
  Pancuronium • Pipecuronium •
  Laudexium • Gallamine

Question 11

Effect of competitive blockers on cardiovascular system:

Answer 11

• Decreased blood pressure - due to histamine
release (benzylisoquinolines)
• Increased heart rate (baroreceptor reflex)
• Coagulability of blood decreased (due to
release of heparin from mast cells)

Question 12

nondepolarizing- neuromuscular blocking agents of most importance in veterinary medicine:

Answer 12

• Atracurium (safe in liver and kidney disease)
• Cisatracurium (used in ophthalmologic surgeries)
• Vecuronium (drug of choice when CV
  stability required)