Protaphane is Novo Nordisks (name/brand) for NPH Insulin - a very, very old insulin (recipe)

Humulin N, Novolin N, Novolin NPH, Gensulin N, SciLin N, Insulatard, NPH Iletin II, and Hypurin NPH are a few other (NPH) Insulins on the market that are close enough to be considered "identical"

Novolin N and Novolin NPH are both produced by the same mfg of the (discontinuing) Protaphane - minimally different recipe but with the same level of blood sugar control (time to start working and how long they last is the primary difference)

Insulin Glargine (Lantus, Basaglar, Toujeo) OR Insulin Detemir (Levemir) would be considered more modern "alternatives" but would also likely come at a cost premium in comparison