MCQ 21

Aspirin: 
a) Selective inhibitor of both COX-1 and COX-2
b) Antiplatelet effect lasts for the life time of platelets, approximately 7-10 days
c) Plasma half life is 1 hour
d) Does not prolong bleeding time




Answer: b (Antiplatelet effect lasts for the life time of platelets, approximately 7-10 days)

MCQ 17:

Mechanism of Action of Dopexamine is:
(a)- Stimulation of Beta 1 adrenergic and Dopamine receptors
(b)- Stimulation of Beta 2 adrenergic and Dopamine receptors
(c)- Inhibition of Beta 1 adrenergic receptors and Stimulation of Dopamine receptors
(d)- Inhibition of Beta 2 adrenergic receptors and Stimulation of Dopamine receptors



Ans: (b) - Stimulation of Beta 2 adrenergic and Dopamine receptors

Vaughan Williams Classification of Anti-arrythmic Drugs

Class	Action	Drugs	Caution
Ia	Sodium channel inhibition: prolong repolarization	Quinidine, procainamide, disopyramide	myocardial infarction, congestive heart failure, renal disease
Ib	Sodium channel inhibition: shorten repolarization	Lidocaine	Proarrhythmias
Ic	Sodium channel inhibition: no effect on repolarization but reduce conductivity	Flecainide, propafenone	Structural heart disease, myocardial infarction, congestive heart failure
II	B-Adrenergic inhibition	Timolol, esmolol, atenolol, bisoprolol	Acute heart failure, bronchospasm
III	Potassium channel inhibition: prolong repolarization	Amiodarone, sotalol	Renal disease, pulmonary disease
IV	Calcium channel inhibition	Verapamil, diltiazem	Not in conjunction with B-blockers
Misc	Na-K ATPase inhibition: potentiate parasympathetic response	Digoxin	Renal disease, hypokalemia

MCQ 6:

All can be given in Aortic Dissection except:

a – Analgesics

b – Sodium Nitroprusside

c – Labetalol

d – Sodium Nitroprusside + Labetalol

Ans B – Sodium Nitroprusside

This is the best answer by exclusion! All of above can be given!Sodium Nitroprusside should be used only in the presence of rate controlling agents.

Care should be taken to avoid direct acting vasodilators in the absence of negative chronotropic medications, as they may induce reflex tachycardia, increasing dP/dT with worsening dissection. (ref: Washington Manual of Critical Care)