00:01
Let's try a question in anticoagulation.
The first question.
00:06
The following medication will act upon thrombin in the serum
and thrombin enmeshed within clots.
00:13
Take a look at these choices
and try to come up with a good answer.
00:20
So the answer is A, bivalirudin.
00:24
Now when we talk about bivalirudin, remember that the heparins
in general like enoxaparin, unfractionated heparins
are generally large molecules,
and they don't go inside the clot.
00:35
They do not work on the thrombin
that is already enmeshed within the clot.
00:40
Protamine is a base that inactivates heparin
and not thrombin, so that's not the choice.
00:46
Fondaparinux is a pentamer moiety
that is cleaved from heparin.
00:50
It does not affect the thrombin
that is already enmeshed within the clot.
00:54
And then of course the bivalirudin
is coming from the medicinal leech,
it's a direct thrombin inhibitor,
and that acts on enmeshed thrombin.
01:03
So, that's why A is the correct answer.
01:06
Here's a great question on coagulation.
A patient with a history of atrial fibrillation
arrives in the emergency room with
an acute GI bleed and a nosebleed.
01:15
He has a medical bracelet that says "anticoagulants".
The spouse says that the patient was not required to have
monthly blood monitoring.
The pharmacy dispensed dabigatran in the last month.
01:26
What would the most appropriate antidote be?
Have a look at these choices,
and tell me which one is the most appropriate antidote.
01:38
So the answer is E, idarucizumab.
01:42
So idarucizumab is a monoclonal antibody.
It is the new way to treat overdose from dabigatran.
01:50
This is a new treatment.
We did not have an antidote until just very recently.
01:55
Before we used to use octoplex or biraplex.
This is an important thing for you to remember,
because when you're using old exams to study from,
the old answer would have been octaplex or biraplex.
02:08
The new answer is this drug.
02:11
We use octaplex and biraplex to treat overdoses of the
new target specific factor Xa inhibitors
like rivaroxaban and apixaban.
02:20
And more recently, this monoclonal antibody
was added to our drug regimen
but this new monoclonal antibody does not
work against rivaroxaban and apixaban.
02:30
Remember that each vial of this drug
is about 3,500 dollars per dose.
02:36
It's exceedingly expensive
but it's also exceedingly active.
02:40
What is the mechanism of action of clopidogrel?
Does it block an enzyme that produces factor VIII?
Is it a cyclooxygenase inhibitor?
Does it bind to ADP receptors or cyclic AMP receptors?
Or does it bind to glycoprotein IIb/IIIa receptors?
The answer is C, it binds to ADP receptors.
03:04
So remember that cloipidogrel binds to the ADP receptor
on the platelet surface.
03:10
This prevents recruitment and aggregation of the platelets.
03:14
Remember that aspirin inhibits cyclooxygenase. Remember that
factor VIII is reduced in certain types of hemophiliacs.
03:22
And direct glycoprotein IIb/IIIa inhibitors are these drugs
here, and they are very active but very specific.