Tag: narrow therapeutic index

Prior authorization for NTI drugs like levothyroxine and phenytoin often blocks brand-name versions despite safety risks. Learn why insurers require them, how state laws are changing, and what to do if your prescription is denied.

Switching between different generic medications can be safe - or risky, depending on the drug. Learn which generics are interchangeable, which ones need caution, and how to protect yourself from dangerous changes.