Random pharmacology questions

Question 1

what is digitalis and how does it work?

Answer 1

this is a cardiac glycoside that reversibly inhibits the Na/K pump. normally this pumps sodium out and K in.
Therefore, inhibition leads to higher intracellular sodium. This change in the membrane potential leads to increased Ca intracellularly. That leads to better contraction.

It also affects the heart rate through impact on the SA/AV nodes to slow conduction.

Question 2

how is digoxin eliminated?

what sort of drugs stuff this up?

Answer 2

this drug is a substrate for the p-glycoprotein pump in the proximal tubule.

unfortunately amiodarone, clarithromycin, verapamil and diltiazem all inhibit the p-glycoprotein pump and can lead to dangerously high levels of drug.