stat pearls not accepted source, UTD needs accepted co-source. cant find anything specific on AMBOSS but says in the drug section, that “Synthesis of vitamin K-dependent coagulation factors is affected soon after absorption (e.g., within 24 hours).” https://next.amboss.com/us/pharma/warfarin?q=warfarin
will need to check with uworld to see what they say, i think this card came from sketchy
FA pg 441 says for warfarin “Slow, limited by half-lives of normal clotting factors”. AMBOSS in discussing warfarin’s adverse effects notes that the half lives of anticoags (protein C/S) is 6-10 hours while half-lives of procoags are 2-4 days. So it has effects within a day but the desired action doesn’t start till later
Think we could leave answer as is but note in extra that clinical anticoagulant effect doesn’t occur until 2-3 days?
Here’s the AMBOSS link: https://next.amboss.com/us/article/Tm06Ug?q=warfarin-induced+skin+necrosis#Zcc47c1739f74989df3136377789a6028
nid:1488765310513 says slow onset is “days.” UW seems to emphasize this point in QID 18688, “Although INR tends to slowly increase in the first few days of administration due to the short half-life of factor VII (4-6 hours), full therapeutic effect does not typically occur for 3 days due to the long half-life of factor Il.” FA23 says “Slow, limited by half-lives of normal clotting factors.” I think we push this and put a note about the change
support this change, personally think 48-72 hours (or 2-3 days) would be better, but fine either way. UpToDate says full effect “does not occur for the first few days” and suggests overlapping heparin + warfarin for the first 5 days minimum @Ahmed7 @herstein.jacob @Sameem @Cameron @Eli.Tanenbaum
Agree with 48-72 hours (feel if we phrased it as 2-3 days it may lead on the answer a bit more)
The FDA says the following: “An anticoagulation effect generally occurs within 24 hours after drug administration. However, peak anticoagulant effect may be delayed 72 to 96 hours.” I think 24-72 is more appropriate.
Onset of action is different from peak action, think 12 to 72 hours is the better one to choose.
@anking-maintainers last call on current version before pushing - 24 hours to onset, 72 hours to achieve peak, think we have a good balance here
Will need rationale in extra before pushing as well
Would do 12-72, as Within suggests earlier than 24.
None of these sources suggest 12 hours though (except the original card, which we have no basis for)