Rising drug prices make headlines, but raw percentage changes can be misleading. A drug used by a handful of patients can show a huge swing from a single reformulation. To find meaningful increases, we rank by year-over-year change in spending per dosage unit and restrict the list to drugs with at least 50,000 Medicare Part D claims.
Fastest-rising prices, 2022 to 2023 (high-volume drugs)
| Drug | Per-unit change YoY | Spend per dosage unit (2023) | Claims |
|---|---|---|---|
| Lagevrio (molnupiravir) | +205% | $0.75 | 383,878 |
| Euthyrox (levothyroxine) | +47% | $0.14 | 108,762 |
| Piperacillin-Tazobactam | +44% | $4.68 | 68,242 |
| Glipizide XL | +39% | $0.33 | 75,839 |
| Meropenem | +35% | $4.26 | 87,893 |
See the full list on the fastest-rising prices ranking.
What is driving these
- Lagevrio is the COVID-19 antiviral molnupiravir. As federal stockpile purchasing wound down, more of its cost flowed through Part D at commercial prices — a structural shift, not a like-for-like price hike.
- Generic shortages. Injectable antibiotics like piperacillin-tazobactam and meropenem saw supply pressure that pushed per-unit costs up.
- Small per-unit dollars. Note how low the absolute per-unit figures are — a few cents can be a large percentage.
Read these with care
Spending per dosage unit mixes price and product mix. A jump can reflect a genuine price increase, a shift to a costlier formulation, or reduced volume. These are aggregate program figures, not the price you pay, and not medical or pricing advice. For context on how the metric is built, see how spending per dosage unit is calculated.
Source: CMS Medicare Part D Spending by Drug, data years 2022–2023, U.S. public domain.