Biosimilar ustekinumab-hmny (Starjemza) injection, billed per 1 milligram administered

Ustekinumab-hmny (Starjemza) is a biosimilar to the reference product ustekinumab (Stelara), an IL-12/IL-23 antagonist monoclonal antibody. This code is billed per 1 mg administered and covers the injectable formulation used for subcutaneous or intravenous delivery depending on the indication and phase of therapy. It is used in the treatment of moderate-to-severe plaque psoriasis, psoriatic arthritis, Crohn's disease, and ulcerative colitis.

This code applies when ustekinumab-hmny (Starjemza) specifically is dispensed and administered, not when the reference biologic or a different biosimilar is used — payer and formulary substitution policies should be confirmed prior to billing. Documentation should reflect the specific product name, lot number, NDC, dose administered in mg, route of administration, and the treating diagnosis. Induction dosing for Crohn's disease and ulcerative colitis is administered intravenously (weight-based), while maintenance and psoriasis/psoriatic arthritis dosing is subcutaneous; ensure the route is clearly documented as it may affect coverage determination.

• Bill units based on the actual mg administered; because dosing varies significantly by indication and weight (e.g., IV induction doses can range from 260–520 mg), accurate unit reporting is critical to avoid underbilling or claim denial.
• Do not confuse with codes for the reference biologic ustekinumab (Stelara) or other ustekinumab biosimilars (e.g., ustekinumab-auub [Wezlana], ustekinumab-ttwe [Selarsdi]); payers may not accept biosimilar substitution without prior authorization or step therapy documentation.
• An appropriate administration code (e.g., 96413 for IV infusion or 96372 for subcutaneous injection) should be reported in addition to the drug code; confirm whether the payer requires a modifier (e.g., JW for discarded drug or JZ to indicate no wastage) per current CMS policy.