University:
University of North Carolina at Chapel Hill
Course:
NURS 312 | Pharmacology
Academic year:

2020
Views:

85

Pages:

1
Author:

folclord7m

1.2 – “Warfari “Warfarin, n, what is it good for?” • Vitamin K (medics with VK symbol on helmets) promotes γ carboxylation of dependent clotting factors – factors II, VII, IX, & X (II: thrombin – beavers foxes; VII: seven deadly sins – devil; IX: cat of nine lives; X: foxes. The VK medic is working on VII, tying his wounds with a γ-shaped bandage.) Vitamin K also activates anticoagulation proteins C & S (Corporal C & Sergeant S in the background are holding back the troops from joining the coagulation war.) Vitamin K epoxide – the inactive form – is reduced to active form by hepatic Vitamin K epoxide reductase (VKOR). (Medic is grabbing a new kit from the VKOR boat.) • Warfarin inhibits VKOR (warfarin warhead has destroyed a VKOR boat), blocking restoration of Vitamin K and reducing systemic Vitamin K levels available to synthesize new clotting factors. This results in a long-lasting, delayed onset hypocoagulable state (undetonated warhead onshore has a ‘delayed onset’). Factor VII has the shortest half-life, so is the first to go down (VK medic is working on VII, who is the first man down). o Warfarin has a long half-life (trooper with a long, narrow white flag) and a narrow therapeutic range, so monitoring via PT/INR is important, testing the extrinsic pathway. Normal INR is 1; goal with warfarin therapy is 2-3. (Para Trooper is coming in as extrinsic reinforcements, with a devil to remind of testing factor VII. INtercom Radio is set between 2 & 3.) Metabolized by CYP450, so has significant drug-drug interactions; upregulation of CYP450 leads to decreased warfarin efficacy, and vice versa (Chrome plated tank with CYP450 license plate is squashing down a warfarin warhead). o Used as treatment/prophylaxis for high-risk coagulable states, including A-fib & DVT (boat with the A-fib monitor floating on the iliofemoral river). Note that in the case of acute thrombus, co-administer heparin for immediate effect. Administered orally (trooper popping pills in the foreground). o Side effects: ▪ Teratogenic, and can cross the placenta (teratogen tarantula on the foreground warhead). Outcome is fetal warfarin syndrome, with abnormalities including low birth weight, slow growth, mental retardation, microcephaly, and malformed bones, cartilage, and joints. LMWH is preferred for anticoagulation in pregnancy. ▪ New warfarin treatment can cause a hypercoagulable state. This results because endogenous antithrombin protein C has a short half-life, so is one of the first factors with levels to fall (warfarin warhead has taken out Corporal C, and troops in the background are charging past Corporal C). This results in patchy skin necrosis (black soot on corporal). Co-administer with heparin to prevent hypercoagulable state (heparin hunters on the bridge are controlling the overzealous coagulation fighters) o Reversal: ▪ Vitamin K has a delayed onset (new vitamin K medics coming in on a boat still in the distance). ▪ Fresh frozen plasma given for immediate effect to replenish factors short term (FFP planes are providing reinforcement in the moment)