Gout- Xanthine Oxidase Inhibitors DI

Question 1

XOIs

Answer 1

Allopurinol, febuxostat

Question 2

XOIs MoA

Answer 2

Inhibits conversion of hypoxanthine to uric acid → decreases uric acid levels in systemic circulation

Question 3

Starting dose of allopurinol

Answer 3

50-100mg QD

Question 4

Dose of allopurinol in normal renal function

Answer 4

100mg

Question 5

Renal dose adjustment for allopurinol

Answer 5

50mg PO QD in CKD Stage 4 or worse

Question 6

Allopurinol dose titration

Answer 6

Titrate q2-5w to target SUA goal <6mg/dl

Question 7

Max dose of allopurinol

Answer 7

800mg

Question 8

Allopurinol ADEs

Answer 8

Rash, DRESS

Question 9

ADE management for allopurinol

Answer 9

D/C

Question 10

Risk factors for rash with allopurinol (drugs)

Answer 10

Risk increases if taken with amoxicilllin, ampicillin, thiazides, ACEIs

Question 11

Allopurinol DDIs

Answer 11

Amoxicillin, ampicillin, thiazides, ACEIs –> rash/SJS, DRESS

Warfarin

6-MP, azathioprine, theophyllline

Question 12

Allopurinol DDI with 6-MP, azathioprine, and theophylline

Answer 12

Xanthine oxidase is involved in all of their metabolisms

Question 13

Allopurinol in the guidelines: when to use it

Answer 13

First line in chronic gout therapy! Can be used regardless if there is overproduction of UA

Question 14

What should be tested for before starting allopurinol?

Answer 14

HLA-B*5801 allele in Asian and African American patients

Question 15

Febuxostat dosing

Answer 15

40mg PO QD, can increase to 80mg PO QD in patients who don’t achieve a serum UA level of <6mg/dl in 2 weeks

Question 16

Febuxostat renal and hepatic dosing

Answer 16

No renal dosing adjustments needed for mild-moderate renal disease (or hepatic impairment), but adjust when CrCl <30ml/min or in severe hepatic impairment

Question 17

Febuxostat ADEs

Answer 17

HA, arthralgias, abdominal pain, nausea, abnormal LFTs, flushing and dizziness

Question 18

Febuxostat monitoring

Answer 18

CV events

Question 19

Febuxostat BBW

Answer 19

Gout patients with established CVD had a higher rate of CV death- try using a different agent for chronic therapy in patients with established CV

Question 20

Febuxostat CIs

Answer 20

Patients who are taking 6-MP, azathioprine, theophylline (relative CI)

Question 21

Febuxostat use with what medications can prevent gout flares?

Answer 21

NSAIDs, colchicine up to 6 months

Question 22

Can febuxostat be D/C’ed during a flare?

Answer 22

Yes, but you don’t need to. Treat the flare normally and continue treatment

Question 23

When to use febuxostat in CV patients

Answer 23

Use in patients who have an inadequate response to a maxed out dose of allopurinol, have an allergy to it, or when treatment with it isn’t advisable