Digoxin

Question 1

digoxin MOA

indication

Answer 1

cardiac glycoside; binds Na/K ATPase in heart, kidneys, intestine, liver, stomach and sk muscle
tx of supra-ventricular dysrhythmias and CHF

Question 2

Digoxin absorption

Answer 2

F = 0.5-1

Question 3

Dig distribution

Answer 3

highly tissue bound, V ~7.3L/kg
20-30% bound to plasma proteins
low rate of distribution

Question 4

how is Dig excreted

Answer 4

50% unchanged in the urine

Question 5

dig t 1/2

Answer 5

30-40h

Question 6

is dig absorption active/passive, saturable/non-saturable?

Answer 6

passive, non-saturable

Question 7

waht drugs decrease Dig F

Answer 7

kaolin-pectin, Al/Mg antacids, cholestyramine

Question 8

____ potassium level –> ______ dig distribution

Answer 8

inc, dec

Question 9

PK model used for Dig

Answer 9

3-compartment (assume one compartment for this lecture tho)

Question 10

renal clearance via ______

renal CL decreased by _____

Answer 10

pgp

quinide, verapamil (pgp substrates)

Question 11

digoxin therapeutic range

Answer 11

0. 5-2.0 ng/mL (NARROW)

* higher needed for afib vs CHF

Question 12

dig AE

Answer 12

AV blovk, premature ventricular contractions (PVCs), atrial tachy-c, sinus brady-c, anorexia, N/V/D

Question 13

dig equilibrium is reached __h after oral dose, ___h after iv dose

Answer 13

6 , 4

anything less than these is not steady state concentrations

Question 14

Vd for dig is based on ______ not _______

Answer 14

patient characteristics not plasma concentration data

Question 15

Dig tablets come in ___

Answer 15

62.5, 125, 150 and 500 ug

Question 16

what is F when doing calculations for po dose

Answer 16

0.7

Question 17

equation for MD

Answer 17

MD = (Cssav desired x CL x tau) / (F x S)

Question 18

LD equation

Answer 18

(Cp x V) / (F x S)

Question 19

multiple dose plasma concentration equation

Answer 19

do C = { (D / FxV ) x e -kt } for each dose, then add each together
we can do this because plasma concentration is not dependent on previous dosing