Impact of IRA Drug Negotiation on Part D Formularies and PBMs | AMCP Annual 2025

The Inflation Reduction Act (IRA) brought on many changes to Medicare Part D, particularly through its drug price negotiation program.

However, its long-term effects on patient access and plan formularies remain uncertain, according to Julie Patterson, Pharm.D., Ph.D., senior director of research at the National Pharmaceutical Council (NPC).

While the law aims to lower costs, shifting incentives could impact coverage decisions in unexpected ways.

At the AMCP 2025 annual meeting in Houston, Patterson discussed these evolving changes in her session, "Inflation Reduction Act Ripple Effects: Considerations for Patient Access and 340B."

She highlighted how early research shows that access to selected drugs has been strong in recent years but warned of potential challenges ahead.

“What we found was that coverage and access were high in 2019 and increasing through 2023, including few utilization management barriers for most of the drugs,” Patterson said.

However, she noted that while Medicare Part D plans must now cover negotiated drugs, there are no firm restrictions on formulary tiering or utilization management.

As a result, insurers may adjust their coverage strategies, particularly if they lose rebate flexibility on negotiated drugs compared to non-selected alternatives.

Beyond drug negotiation, Patterson pointed to further shifts in Medicare Part D, including its benefit redesign.

She discussed that recent NPC research found an 11.4 percentage point decrease in the proportion of beneficiaries with covered access to drugs in competitive classes between 2024 and 2025.

This suggests that as insurers navigate new financial pressures, they may call for more strict coverage policies.

With Medicare formularies, premiums and plan incentives in limbo, Patterson stressed the importance of continued monitoring of patient access changes in this changing landscape.