Basic Pharmacology

Question 1

Atracurium - Mechanism of action

Answer 1

Atracurium is a benzylisoquinolinium non-depolarising neuromuscular blocking drug. It competes with acetylcholine for motor end-plate cholinergic receptors and blocks neuromuscular transmission. This leads to skeletal muscle relaxation.

Question 2

Atracurium - Preparation and Dose range

Answer 2

10mg/mL
Initially 400-500mcg/kg
Maintenance
IV injection: 100-200mcg/kg as required
IV infusion: 300-600mcg/kg/hr

Question 3

Atracurium - ADRs

Answer 3

Hypotension
Tachycardia
Bronchospasm
Skin flushing

Question 4

Rocuronium - Mechanism of action

Answer 4

Rocuronium is an aminosteroid non-depolarising neuromuscular blocking drug. It competes with acetylcholine for motor end-plate cholinergic receptors and blocks neuromuscular transmission. This leads to skeletal muscle relaxation.

Question 5

Rocuronium - Preparation and Dose range

Answer 5

10mg/mL
Initially 600mcg/kg
Maintenance
IV injection: 150mcg/kg (elderly 75-100mcg/kg)
IV infusion: 300-600mcg/kg/hr (elderly up to 400mcg/kg/hr)

Question 6

Rocuronium - ADRs

Answer 6

Hypotension
Tachycardia
Bronchospasm
Skin flushing

Question 7

Vecuronium - Mechanism of action

Answer 7

Vecuronium is an aminosteroid non-depolarising neuromuscular blocking drug. It competes with acetylcholine for motor end-plate cholinergic receptors and blocks neuromuscular transmission. This leads to skeletal muscle relaxation.

Question 8

Vecuronium - Preparation and Dose range

Answer 8

10mg powder
Initially 80-100mcg/kg
Maintenance
IV injection: 20-30mcg/kg, adjusted to response (max 100mcg/kg in C-section)
IV infusion: 0.8-1.4mcg/kg/minute (48-84mcg/kg/hr)

Question 9

Vecuronium - ADRs

Answer 9

Hypotension
Tachycardia
Bronchospasm
Skin flushing

Question 10

Atracurium - Onset and Duration of action

Answer 10

Onset of action: 2-2.5 minutes

Duration of action: 35-45 minutes (regain 25% of control)

Question 11

Rocuronium - Onset and Duration of action

Answer 11

Onset of action: 45-120 seconds

Duration of action: 30-90 minutes

Question 12

Vecuronium - Onset and Duration of action

Answer 12

Onset of action: 90-120 seconds

Duration of action: 25-30 minutes

Question 13

Suxamethonium - Mechanism of action

Answer 13

Suxamethonium is a depolarising neuromuscular blocker that binds to cholinergic receptors at the motor end-plate. Initially depolarisation causes skeletal muscle fasciculation. The action of acetylcholine is then blocked preventing neural transmission and producing muscle relaxation.

Question 14

Suxamethonium - Preparation and Dose range

Answer 14

50mg/mL
0.6mg/kg in adults (range 0.3-1.1mg/kg)
1-2mg/kg in children
Administered IV over 10-30 seconds

Question 15

Suxamethonium - Onset and Duration of action

Answer 15

Onset of action: 60 seconds

Duration of action: 4-6 minutes

Question 16

Suxamethonium - ADRs

Answer 16

Hypotension
Myalgia
Rash
Malignant hyperthermia
Rhabdomyolysis
Transient ocular hypertension

Question 17

Morphine - Mechanism of action

Answer 17

Morphine is a full opioid agonist. Opioid agonists bind to opiate receptors in the brain and spinal cord resulting in inhibition of the ascending pain pathways thus altering the perception and response to pain. Morphine reduces breathlessness and respiratory effort by reducing ventilatory drive in hypoxic and hypercapnic states. The sedating effect may also reduce anxiety associated with breathlessness. Cough suppression results from direct central action on the cough centre in the medulla.

Question 18

Morphine - Preparations and Dose range

Answer 18

Oral: Controlled release - M-Eslon (sulfate); Immediate release - Sevredol (sulfate), elixir (hydrochloride)
SC/IM/IV: Morphine sulfate, multiple dose preparations
IT: Morphine sulfate (200mcg in 0.4mL; 300mcg in 0.3mL)

Question 19

Morphine - ADRs

Answer 19

Sedation
Respiratory depression
Nausea/vomiting
Constipation