Tips for safe use of allopurinol Save

These are tips and hopefully the patients are abstaining from moderate alcohol and are not tipsy! Here are 5 tips that may not be totally obvious.

1. Have a good reason to use chronic urate lowering therapy. If using allopurinol for gout, it is a forever medication for the most part. So be sure that there is a good reason to prescribe it. Main indications, tophi, recurrent gout >2 attacks/yr that occur after lifestyle and medication modification. The traditional thinking is to go low and slow with allopurinol dosing. This should reduce hypersensitivity reactions and possibly less initial gout flares. The problem though is that it takes longer to get to uric acid target and every time you increase the dose, there is a risk of flaring.
2. Flare prophylaxis may be needed but at least one study shows you can start allopurinol right away if indicated instead of waiting for a gout attack / flare to end but of course with prophylaxis.
3. People of SE Asia (Han Chinese, Thai, Korean) have more severe skin reactions (hypersensitivity) and should be tested for HLAB*58:01 prior to Allopurinol use, and start lower
4. SGLT2i can increase gout initially and then act like allopurinol reducing purine metabolism.
5. Beware of SLE patients with gout – these patients may be on azathioprine – very dangerous interaction! They often have CKD which increases the risk further.

Stop AZA if possible BEFORE starting allopurinol. Lower the dose of AZA to ¼ of the current dose if you MUST use it and do frequent CBC, diff at first. 

Allopurinol blocks xanthine oxidase which is how AZA is metabolized. 

MMF has less interactions with allopurinol but still use with caution.