Antiarrhythmics, antihypertensives, vasopressors, inotropes

Question 1

Categorise the following drugs into their Vaughan-williams classification:
- Dititazem
- Lidocaine
- Esmolol
- Amiodarone

Answer 1

• Class 1 Sodium channel blockers: lignocaine
• Class 2 Beta blockers: esmolol
• Class 3 Potassium channel blockers: Amiodarone also blocks all other channels too
• Class 4 Calcium channel blockers: diltazem

Question 2

Is esmolol cardioselective?

Answer 2

yes

Question 3

What is the timeframe for onset of action of oral metoprolol

Answer 3

< 1 hour

Question 4

What is the oral dose equivalent to 5mg IV metoprolol?

Answer 4

12.5mg PO metoprolol

Question 5

What is the MOA of labetalol

Answer 5

• alpha 1 blocker: vasodilation
• non-selective beta-blocker: decrease HR, contractility may cause broncospasm
• beta block +++ alpha block +

Question 6

Does amiodarone need to be diluted when given in cardiac arrest?

Answer 6

no

note: incompatible with sodium bicarbonate. flush line well if giving both

Question 7

What are common side effects of adenosine?

Answer 7

• chest discomfort
• headache
• flushing
• nausea
• rarely broncospasm and AF

symptoms short lived

Question 8

what is the “antidote” to extravasation of inotropes esp. high risko onces like noradrenaline

Answer 8

• Phentolamine 5 to 10 mg diluted in 10 mL sodium chloride 0.9%, infiltrated into the affected region via multiple subcutaneous injections as soon as possible but up to 12 hours
• nitroglycerine ointment

Question 9

When extravasation accidents happen due to peripheral infusion of vasopressors, what are the high risk locations?

Answer 9

Below anticubital fossa or below popliteal fossa

Question 10

What receptors does vasopressin work on?

Answer 10

• V1 vascuar smooth muscle: vasoconstriction (non-adrenergic)
• V2 kidney: antidiuretic effect

0.04 unit/min