HCPCS Code Q5121: Injection, Infliximab‑axxq (Avsola®), Biosimilar, 10 mg

HCPCS code Q5121 covers infliximab-axxq (Avsola®) IV infusion for autoimmune diseases like rheumatoid arthritis, Crohn’s, and ulcerative colitis.

Use Code

## **What is HCPCS code Q5121?** HCPCS code Q5121 refers to the injection of infliximab-axxq (Avsola®), a biosimilar to infliximab, billed per 10 mg unit. Avsola is indicated for autoimmune conditions—including rheumatoid arthritis, rheumatoid factor-positive rheumatoid arthritis, Crohn’s disease, ulcerative colitis, psoriatic arthritis, ankylosing spondylitis, plaque psoriasis, and psoriasis—and is administered via intravenous infusion in physician offices or infusion settings. It may be prescribed for adult patients with active disease who have had an inadequate response to conventional therapy or other systemic therapies. As a biosimilar, Q5121 aligns with CMS’s biosimilar code structure, facilitating direct reimbursement in outpatient settings. Units billed correspond precisely to actual mg administered (e.g., 300 mg = 30 units). Prior authorization is commonly required. Modifier and wastage rules align with other biologics: JW for partial vial waste, JZ if no waste. Claims must include NDC, lot number, and diagnosis to support medical necessity. For joint-related conditions, documentation may specify an unspecified site, such as unspecified knee, unspecified shoulder, unspecified elbow, unspecified wrist, unspecified hip, or unspecified ankle, as applicable to the patient’s diagnosis and organ or system involvement.

## **HCPCS code Q5121 documentation requirements** The billing requirements for HCPCS code Q5121 (injection of infliximab-axxq, biosimilar Avsola, 10 mg) include the following key points: - Report HCPCS Q5121 to document the administration of infliximab-axxq in 10 mg units. - Use the JW modifier on Medicare Part B claims when any amount of the drug is discarded and not administered to the patient, as this is required for single-use vial drugs. - Include the appropriate CPT code for the intravenous infusion or administration procedure alongside Q5121 (for example, CPT 96413 for chemotherapy administration, or 96365, which may be used depending on payer instructions for biologics used in autoimmune disorders). - Submit accurate diagnosis codes (ICD-10) supporting the medical necessity of the drug, corresponding to the patient's condition, such as autoimmune disorders, rheumatoid arthritis, psoriatic arthritis, ulcerative colitis, Crohn’s disease, or ankylosing spondylitis, treated by infliximab-axxq, with proper precautions in cases where it may have adverse outcomes. - Enter the National Drug Code (NDC) in claim forms if required by the payer (e.g., Medicaid and some commercial insurers). - Record service units accurately according to the actual amount administered (1 unit = 10 mg). - Complete all other claim fields accurately, such as the date of service, total charges, and revenue codes (Medicare uses revenue code 0636 for this specific drug). - Ensure clinical documentation supports the drug’s use, including diagnosis, treatment rationale, prior therapy history, and presence of organ or systems involvement, to justify billing and reimbursement. - Verify payer-specific policies for any additional or varying billing requirements, as Medicare, Medicaid, and commercial insurers may have differences. The Medicare reimbursement rate for HCPCS Q5121 is around $23.24 per 10 mg injection in 2025, with variations depending on region and payer contracts.

## **HCPCS code Q5121 billing requirements** The billing requirements for HCPCS code Q5121 (injection of infliximab-axxq, biosimilar Avsola, 10 mg) include the following key points: - Report HCPCS Q5121 to document the administration of infliximab-axxq in 10 mg units. - Use the JW modifier on Medicare Part B claims when any amount of the drug is discarded and not administered to the patient, as this is required for single-use vial drugs. - Include the appropriate CPT code for the intravenous infusion or administration procedure alongside Q5121 (for example, CPT 96413 for chemotherapy administration or 96365 for intravenous infusion). - Submit accurate diagnosis codes (ICD-10) supporting the medical necessity of the drug, corresponding to the patient's condition, such as autoimmune disorders treated by infliximab-axxq. - Enter the National Drug Code (NDC) in claim forms if required by the payer (e.g., Medicaid and some commercial insurers). - Record service units accurately according to the actual amount administered (1 unit = 10 mg). - Complete all other claim fields correctly, such as date of service, total charges, and revenue codes (Medicare uses revenue code 0636 for this drug). - Ensure clinical documentation supports the drug’s use, including diagnosis, treatment rationale, and prior therapy history, to justify billing and reimbursement. - Verify payer-specific policies for any additional or varying billing requirements, as Medicare, Medicaid, and commercial insurers may have differences. The Medicare reimbursement rate for HCPCS Q5121 is around $23.24 per 10 mg injection in 2025, with variations depending on region and payer contracts.

## **Other relevant codes** Here is the list of other relevant HCPCS codes to Q5121 in bullet format: - **Q5102**: Injection, infliximab, biosimilar, 10 mg - **Q5103**: Injection, infliximab-dyyb, biosimilar (Inflectra), 10 mg - **Q5104**: Injection, infliximab-abda, biosimilar (Renflexis), 10 mg - **Q5115**: Injection, rituximab-abbs, biosimilar (Truxima), 10 mg - **Q5118**: Injection, bevacizumab-bvzr, biosimilar (Zirabev), 10 mg - **Q5119**: Injection, rituximab-pvvr, biosimilar (Ruxience), 10 mg - **Q5122**: Injection, pegfilgrastim-apgf, biosimilar (Nyvepria), 0.5 mg - **Q5123**: Injection, rituximab-arrx, biosimilar (Riabni), 10 mg

Frequently asked questions

Infliximab is used to treat autoimmune diseases characterized by inflammation, including Crohn’s disease, ulcerative colitis, rheumatoid arthritis, ankylosing spondylitis, psoriatic arthritis, and plaque psoriasis.

The CPT codes for REMICADE (infliximab) infusion are 96413 for the first hour of infusion and 96415 for each additional hour. The drug itself is billed with HCPCS code J1745 (Injection, infliximab, 10 mg, excluding biosimilars).

Semaglutide injection is generally coded using HCPCS codes related to the specific drug product (such as OZEMPIC or WEGOVY). It is administered subcutaneously, and drug injection CPT codes like 96372 (injection of drug or substance under skin or into muscle) may apply for the administration procedure.