Tag: narrow therapeutic index

Georgea Michelle, Mar, 24 2026

Phenytoin and Generics: What You Need to Know About Therapeutic Drug Monitoring

Phenytoin has a narrow therapeutic window and non-linear metabolism, making generic substitutions risky. Therapeutic drug monitoring is critical when switching formulations to prevent toxicity or seizure breakthrough.

Georgea Michelle, Jan, 20 2026

Prior Authorization for NTI Drugs: When Insurers Require Brand-Name Medications

NTI drugs like levothyroxine and phenytoin require extreme precision - yet insurers often delay brand-name access with prior authorization. Learn why this practice is dangerous, how states are changing the rules, and what patients can do now.