Oakland, CA – Psychotherapeutic & Neurological Drugs account for less than one-third of one percent of all prescriptions dispensed to California injured workers but due to their high average cost per prescription they are now among the 10 most costly drug groups in California workers’ compensation according to a new California Workers’ Compensation Institute (CWCI) study.

The study, based on a decade’s worth of data (2015–2024) from CWCI’s Prescription Drug Interactive Application and Industry Research Information System database, shows that while Psychotherapeutic & Neurological Drugs represented only 0.2% to 0.3% of all California workers’ compensation prescriptions throughout the 10-year study period, their share of total pharmacy payments in the system increased nearly fivefold, climbing from 0.7% in 2015 to 3.4% in 2024. The study attributes much of that surge to the use of certain high-priced brand medications within the drug group.

CWCI identified five drugs that accounted for 92.9% of the Psychotherapeutic & Neurological Drug prescriptions dispensed to injured workers in 2024, and about 60% of the payments in that drug group: memantine HCl (Namenda), donepezil HCl, gabapentin enacarbil ER (Horizant), once-daily gabapentin (Gralise), and dextromethorphan HBr quinidine sulfate (Nuedexta). Of these five drugs, Nuedexta was the main cost driver over the past decade, as its share of the prescriptions within the drug group quadrupled from 8.6% in 2015 to 35.9% in 2024, while the average payment doubled from $659 to $1,317, driving its share of the drug spend within the drug group from 13.9% to 41.2%. A review of diagnosis and body part codes on claims in which Nuedexta and other Psychotherapeutic & Neurological medications were prescribed suggests some off-label use of these drugs for conditions unrelated to FDA-approved indications or the Medical Treatment Utilization Schedule (MTUS)/ACOEM Guidelines.

The report also highlights broader factors contributing to changes in the prescribing patterns for Psychotherapeutic & Neurological drugs, including the decline in opioid prescribing and greater reliance on alternative pain medications, specialty drug pricing, questionable marketing of drugs for off-label use, and the adoption of and changes to the MTUS Formulary. While some Psychotherapeutic & Neurological Drugs such as memantine HCl and donepezil HCl show minimal cost impact due to low pricing and generic competition, others continue to exert upward pressure on the total workers’ comp drug spend.

The Institute notes that although this drug group continues to account for only a tiny fraction of all prescriptions, the growth in its share of the total drug spend underscores the importance of ongoing monitoring, guideline compliance, and early identification of potential off-label or unsupported use.

The full report, “Emerging Drug Classes in California Workers’ Compensation: Psychotherapeutic &  Neurological Drugs,” is available to CWCI members and subscribers in the Research section at www.cwci.org. Others may purchase the report for $18 from the Institute’s online store, here.