Is this the same as the OTC supplement N-A-G?
N-A-C
These are examples of the supplements:
Source Naturals:
https://www.amazon.com/Source-Naturals-N-Acetyl-Glucosamine-Supplement/dp/B000EQ6H1Q
Bulk Supplements:
https://www.amazon.com/N-Acetyl-D-Glucosamine-BulkSupplements-Digestive-Support/dp/B074JHM2NB