Found a two-letter imprint with no box. Before I guess, here is everything I can see.

Reagent tests are a screen, not an assay. They rule a family in or out and say nothing about dose.

The same imprint exists in several markets for different products, so country matters more than the database.

Light quality ruins more identification photos than anything else. Daylight, no flash.

Weight and dimensions are how blank tablets get identified, and you cannot do that from a photo.

Any ideas welcome, and I will report back what the pharmacist says.