NAPLEX Question of the Week: Anticoagulation
Anticoagulation is involved in different disease states associated with clotting (e.g. venous thromboembolism (VTE), atrial fibrillation (a fib), and clotting disorders) in both the inpatient and outpatient setting. There are specific dosing regimens to know as a pharmacist based on indication.
AB is a 59-year old male, weighing 81 kg, with a SCr of 1.2 mg/dL. He presents to your pharmacy today with a new prescription for a blood thinner. Upon further questioning, you find out that the patient was just discharged from the hospital and recently diagnosed with atrial fibrillation and has a CHADS2-VASC score of 3. His PMH includes HFrEF, DM, HTN, dyslipidemia, gout, GERD, and now atrial fibrillation. He is currently taking lisinopril 40mg daily, metformin 1g BID, atorvastatin 40mg daily, allopurinol 300mg daily, pantoprazole 40mg daily, and carvedilol 12.5mg BID. Which of the following agents would be a correct choice for AB?
a. Dabigatran 150mg orally daily
b. Lovenox 40 mg subcutaneous daily
c. Rivaroxaban 15 mg PO BID x 21 days, then 20 mg daily
d. Apixaban 5 mg PO BID
e. Aspirin 81mg PO daily
Answer with Rationale:
Answer: d - apixaban 5 mg PO BID is the appropriate dosing for atrial fibrillation.
Additionally, a unique pearl regarding apixaban dosing is the following. Apixaban should be dose reduced to 2.5 mg BID if the patient has 2 of the following: age 80 years old or older, weight 60 kg or less, and/or SCr 1.5 mg/dL or greater. This patient does not meet any of these, thus the normal atrial fibrillation dosing for apixaban is correct. NOTE: These dosage adjustments do not apply when using apixaban for VTE treatment as everyone should receive 10mg BID for 7 days followed by 5mg BID.