The three largest pharmacy benefit managers — Caremark, Express Scripts and Optum Rx — each excluded more than 600 drugs from their 2026 formularies, reflecting shifts in drug pricing models that are beginning to challenge traditional formulary strategies, according to an April 6 report from the Drug Channels Institute.
Exclusions remain a central tool for PBMs to negotiate rebates and manage drug access. However, Express Scripts expanded its list significantly in 2026, adding a notable number of exclusions, including multisource generics, older brand-name drugs and certain diabetes treatments.
PBMs are also continuing to favor private-label biosimilars tied to their parent companies, particularly for high-cost biologics such as Humira and Stelara, the report said. In some cases, formularies prioritize affiliated products over competing biosimilars even when those alternatives carry lower list prices.
Meanwhile, pricing dynamics are evolving. A Stelara biosimilar is now available through a direct-to-patient model for $360 per dose, or $1,380 annually — about 96% below the reference product’s list price — highlighting growing pressure on rebate-driven formulary models.
The report found the Inflation Reduction Act has had limited impact on commercial formularies so far, with the 10 drugs selected for Medicare price negotiation not widely excluded or disadvantaged.
These trends suggest PBMs’ traditional leverage may weaken as the market shifts toward net pricing, lower list prices and direct-to-patient distribution models, according to the report.
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