How do PBM rebates help Pfizer's Vyndamax?
A ~$74,000 gap between Vyndamax's list and net price flows through the supply chain as rebates — calculated on list price, meaning patients' coinsurance is higher, a dynamic the FTC has alleged in the insulin market favours high-list-price incumbents.
Pfizer does not disclose its tafamidis rebate contracts, but the way Medicare Part D rebates work explains why critics believe they favour the incumbent. Manufacturers pay rebates to PBMs, which share them with plans, to win formulary placement, with the aim of including their product while excluding competitors or securing preferred status. A drug with around 75% of prescriptions can offer rebates across a far larger patient base than a newcomer. Rebates are typically calculated from list price, and patients' coinsurance is usually applied to the price before the rebate is subtracted, so a high list price can suit both manufacturer and PBM while patients pay more. ICER put tafamidis at nearly $268,000 list against about $194,000 net, a gap of about $74,000 per patient-year flowing through the supply chain. From 2025, plans bear 60% of catastrophic-phase costs, and Milliman says plans may demand much higher rebates on high-cost drugs as a result. The FTC has alleged, in the insulin market, that PBMs favoured high-list-price, high-rebate products.