Why Wasn't Myrbetriq Chosen for the First Year of the CMS Negotiation Program?

Objectives: We analyzed mirabegron’s absence from drugs chosen by the Centers for Medicare/Medicaid Services (CMS) for the first year of its Drug Negotiation Program (DNP). CMS is America’s largest insurer, but 2005 medication coverage legislation included a "noninterference" clause prohibiting CMS from leveraging its bargaining power to negotiate prices. Recently, the 2022 Inflation Reduction Act created the DNP, directing CMS to negotiate prices starting in 2023 with the 10 most costly drugs. AUGS guidelines state mirabegron is preferred over anticholinergics for overactive bladder (OAB) management in older adults due to dementia concerns, but it’s currently underutilized due to cost. Mirabegron was the only eligible Beta-3 agonist, but was not chosen in 2023 for new pricing in 2026.

Methods: We modeled CMS's 2023 selection process using publicly available 2021 drug expenditure dashboards. Among the 20 most costly drugs (amount paid by CMS+beneficiary), we excluded those ineligible in 2023. For the remaining drugs, we categorized them as chosen/not chosen for the 2023 DNP. For drugs not chosen, we used growth in price and beneficiary utilization from 2017-2021 to project 2023 CMS costs. Using 2021 utilization for each anticholinergic OAB drug, we calculated percentage needed to switch to mirabegron for 2023 DNP inclusion.

Results: In 2021, mirabegron was the 14th most costly drug ($1,989,099,248 for 665,158 beneficiaries). When excluding ineligible drugs, it was 10th most costly (table 1). Mirabegron is the only of the top-20 drugs in 2021 that was eligible in 2023 but not selected for the DNP. Anticholinergic OAB drugs were prescribed 3 times as often but at one third the total cost of mirabegron ($653,669,038 and 2,105,713 beneficiaries). The cost per dose of Myrbetriq increased 4.5% from 2020 to 2021, a rate that was lower than 9 of 10 DNP drugs. Using the nearly perfect linear rate of growth between 2017 and 2021 (R2 = 0.995), we estimated a 2023 total cost of $2,492,214,534, which was 96.7% the total cost of insulin aspart, the 10th and final DNP drug. Switching 1.2% of 2021 anticholinergic OAB prescriptions to mirabegron by 2023 would have allowed mirabegron to become the 10th DNP drug. Transitioning 6% of 2021 anticholinergic patients would have had mirabegron claim the 6th spot, while transitioning 63% would have led it to displace Jardiance from the #2 spot (Figure 1).

Conclusions: Mirabegron came exceedingly close to DNP selection, and will likely be added in 2024. Once mirabegron drug price is reduced by DNP negotiations or biosimilar availability, far more anticholinergic users will likely be transitioned to mirabegron.