The syringe Medicare doesn't cover set the price of the vial it does

What Medicare Part B pays per milligram in the October 2026 quarter, by label, next to what one milligram costs in cash at Cost Plus. The Part B amount is the payment limit CMS publishes for each billing code. The Cost Plus amount is the syringe price divided by its milligrams.

A new code's first payment limit can sit far above where it settles. Two separate CMS rules can hold it there. A new code has no sales history yet, so CMS prices it by an interim rule until sales data arrive. And a code that carries a form Part B does not cover is priced off both forms until CMS excludes the uncovered one. The file does not say which rule applies to a given row, so the table shows the size of each fall, not its cause.

Among ustekinumab, five codes opened between 2.5 and 8.1 times their latest final limit. Four of them are the codes the Inspector General named, and CMS applied the exclusion to them in April 2026. Wezlana only ever held the vial and still fell more than fivefold, so the syringe does not explain every fall. Pyzchiva, also vial-only, opened 8 percent above where it settled.

Outside ustekinumab, 10 of the 13 codes settled within 10 percent of where they opened. The three exceptions are Hercessi, a trastuzumab, which opened at 2.5 times, and two tocilizumabs, Avtozma at 1.5 times and Tofidence at 1.27.

Biosimilars now exist for 21 reference biologics. On the crowded ones, competition has already pulled the cheapest option far below the original: rituximab by 92%, trastuzumab by 84%, ustekinumab by 78%, denosumab by 74%, bevacizumab by 72%. Denosumab has 19 licensed biosimilars, the most of any molecule.

That collapse happens at the Medicare payment limit, which is what a clinic or hospital is reimbursed. Most of these are infused or injected in a medical setting rather than dispensed to a patient, so a cash pharmacy price is not a like-for-like substitute. What the table shows is where supply has already multiplied and where it has not.

CMS sets a code's payment limit from the average sales price of every NDC in that code. Five ustekinumab biosimilars put the 130 mg vial and the self-administered syringe in one code. The syringes cost more per milligram, so they pulled the vial's limit up. In the fourth quarter of 2025 Stelara's limit was $12.99 per mg, or $1,689 a vial. The HHS Inspector General found one biosimilar at $5,245 a vial.

The law already had a remedy. Since 2021, CMS can compute the limit twice, with and without the non-covered forms, and pay the lower amount (Social Security Act section 1847A(g); 42 CFR 414.904(d)(4)(iv)). CMS uses it only after the Inspector General names the product. That report, OEI-BL-25-00240, came out on 12 December 2025. CMS applied the exclusion in the April 2026 file. The four codes it named fell 60 to 87 percent from January to April, in line with the Inspector General's estimate of 59 to 87 percent.

The exclusion was not the only change that quarter. April 2026 was also the first file priced on a full quarter of sales. Wezlana and Pyzchiva, the two codes that only ever held the vial, fell 61 and 45 percent in the same file with no exclusion. The table shows both effects together, and this page does not credit the exclusion with the whole fall.

One restatement to note. CMS revises past quarters, and our files are the current revisions. Selarsdi's October 2025 row reads "Updated April 2026", so our $37.52 per mg is CMS's later figure, not the one first published. The Inspector General used the original, which is why its figure is higher.

Most ustekinumab is a subcutaneous maintenance dose, one 45 mg or 90 mg syringe every 8 to 12 weeks, and it runs through Part D. Part D gross spending on Stelara tripled from 2020 to 2024. It reached $3.38 billion for 24,754 beneficiaries: $136,464 per person and $25,424 per claim, before manufacturer rebates. The cash price of the same dose, as a Starjemza syringe at Cost Plus, is $360.

Adalimumab (Humira) went through the same transition in 2023. By 2024 nine biosimilars were on the market. Part D still paid $5.72 billion for Humira on 652,028 claims, $8,766 per claim. The biosimilars together drew $162 million on 51,072 claims, $3,173 per claim. Humira kept 92.7% of adalimumab claims in its second year of competition. Cost Plus sells a two-pen adalimumab-fkjp kit, a month at the standard 40 mg every-other-week dose, for $423.25.

Every biosimilar and interchangeable product licensed by FDA under section 351(k), with its reference product, and the Part B payment limit for each where a billing code exists in the October 2026 file. "Ratio" is the biosimilar limit divided by the reference limit when both are priced per the same unit. 55 pairs have both codes. 20 biosimilars are paid at under half the reference. 10 are paid at or above it. 42 biosimilars have no Part B code, mostly because they are pharmacy-dispensed (adalimumab, etanercept, insulins) or too new.

Sources. Medicare Part B payment limits come from the CMS ASP Pricing Files, quarterly, final files through October 2026. The vial and syringe mechanism is documented by the HHS Office of Inspector General, report OEI-BL-25-00240 (12 December 2025), and by 42 CFR 414.904(d)(4)(iv). Biosimilar and interchangeable licensure comes from the FDA Purple Book. Medicare spending comes from the CMS Medicare Part B and Part D Spending by Drug files, calendar years 2020 to 2024. Cost Plus Drugs prices were captured from the company's medication pages on 2026-09-11 and are the listed price for one syringe or kit, before shipping and dispensing fees.

Every figure on this page is pulled from the public Verzi Health data API, endpoints /rx/biosimilars, /rx/asp, /rx/spending and /rx/cost-plus, so the page and the API always agree.

Matching. Each Purple Book product is matched to a Part B billing code through the CMS NDC-to-HCPCS crosswalk for the same quarter, by brand name. The reference product is matched the same way. Where a brand maps to more than one code, the code with the most NDCs is used.

Caveats. The payment limit is what Medicare pays a physician or hospital outpatient department per billing unit. It includes the statutory add-on, which for a biosimilar is computed on the reference product's average sales price, so a biosimilar limit is not the biosimilar's own sales price. A new code's first limits can sit far above where it settles, for two reasons the file does not separate: the code has no sales history yet, and a code that blends covered and non-covered forms is priced off both until CMS excludes the non-covered one. CMS also revises past quarters; this page uses the current revision of each. Part D figures are gross drug cost before manufacturer rebates, which for Stelara and Humira are large and confidential. Part B and Part D reach different patients through different channels; the comparison here is the price of the same milligrams, not a claim that one could replace the other. Otulfi's Cost Plus price ($877.50 for 45 mg, $1,350 for 90 mg) is higher per mg than its Part B limit; Starjemza's is lower than every Part B ustekinumab limit.