GI mc3 Flashcards
lithium is the treatment of choice in
acute mania and in prophylaxis of manic depression
lithium and toxicity outcome
producing dose-dependent and dose-independent side effects
how is lithium distributed
unevenly, -0.7L/kg volume distribution
Volume distribution
the theoretical volume that would be necessary to contain the total amount of an administered drug at the same concentration that is observed in the blood plasma.
lithium distribution model
two-compartment model
lithium distriibution time
8 hours
lithiu half life
20-24 hours
how long does it take lithium to reach a steady state
5-6 days
how many half lives does it take lithium to reach steady state
5
digoxin half life
36
digoxin reaches steady state in how many days
5-7
why do a loading dose
steady state plasma concentration must be reached more rapidly
how do you do a loading dose
big dose on the innitiation of treatment
Volume of distribution of digoxin =
7.3 L/kg
what does Volume of distribution of digoxin suggest
widely distributed outside the water compartment and is also protein bound or distributed by some other tissue type
what places does digoxin have a high affinity for
skeletal and cardiac muscles, intestines and kidneys
what should digoxin dosing be based on
estimated lean body mass
where are lipid soluble drugs stored
fat
which drugs have a high volume of distribution
drugs that accumulate in organs either by active transport or by specific binding to tissue molecules
what drugs is bone a resevoir for
tetracycline and heavy metals
where is digoxin excreted
Most digoxin is eliminated unchanged by the kidneys
patients w renal impairment and digoxin vod
vod reduced
what mediates tubular digoxin secretion
p-glycoprotein
what can inhibit p-glycoprotein
spironolactone, quinidine, verapamil and amiodarone
renal failure affect on clearance of digoxin
decreases
where can digoxin be metabolised
tiny bit in the liver
8% undergoes an enterohepatic cycle.
is dogoxin absorbed in the gut
ye but poorly
oral bioavailability of digoxin level
high
Bioavailability
fraction of a dose of drug that is absorbed from its site of administration and reaches in an unchanged from the systemic circulation.
what happens to digoxin in the gut
metabolised
how is digoxin metablised in the gut
hydrolysed by acid in stomach
bacteria in the intestines
what does the bioavailability of a drug depend on
absorption across the intestinal wall.
Decomposition of the drug in the lumen.
pH and perfusion of the small intestine.
Surface and time available for absorption.
Competing reactions in the lumen (for example of the drug with food).
Hepatic first-pass effect.
whats more bioavailable liquid digoxin or tablet
liquid
