Thanks! It's a really good feedback, when you ask good questions just after the tutorial.
to make the life easier I would recommend to use ATC concepts as a drug classes idetifier.
Others sources have pretty messy structure, and we don't have use cases where people need that, so we put them in OHDSI vocabulary as they are.
SELECT max_levels_of_separation, concept.*
JOIN concept ON ancestor_concept_id = concept_id
WHERE descendant_concept_id = 1503297
and vocabulary_id in ('ATC')
ORDER BY max_levels_of_separation, concept_name