During your rural posting after the internship, you encounter a patient of acute cardiac failure. Your preferred drug for this condition is dobutamine. However, it is not available there. Which of the following other drugs, or combination of drugs, would be a suitable alternative, giving the pharmacologic equivalent of what you want the dobutamine to do?
Dobutamine acts mainly on b1 receptor. Dopamine at very high dose stimulates D1,b1, a1. Ephedrine leads to release of noradrenaline which will stimulate a1,a2 and b1 receptors but propanolol will block b receptor. So net effect of Ephedrine + propranolol would be stimulation of a1,a2 receptors. Noradrenaline stimulates a1,a2 and b1 receptors but phentolamine is an a blocker. So, net effect of this combination would be stimulation of b1 receptor. Methoxamine is a1 agonist and atropine is muscarinic blocker. So , the combination providing same effect as of dobutamine is Noradrenaline + phentolamine.
Dopamine (at a very high dose)
Ephedrine plus propranolol
Norepinephrine plus phentolamine
Methoxamine plus atropine
Sympathetic System