Why can’t I find information about a scored, white, round pill with the imprint I 135?

Description:
I on top break line (score) 135 beneath on one side, plain on the other side, white, round, flat.

The pill is Allopurinol 100mgs.

Allopurinol belongs to a class of medications called xanthine oxidase inhibitors. It works by reducing the production of uric acid in the body. High levels of uric acid may cause gout attacks or kidney stones.

Allopurinol is used to treat gout (a type of arthritis in which uric acid, a naturally occurring substance in the body, builds up in the joints and causes sudden attacks of redness, swelling, pain, and heat in one or more joints). Allopurinol is used to prevent gout attacks, not to treat them once they occur.

https://www.drugs.com/allopurinol.html