Voxzogo (vosoritide) — HCPCS J3490 (medical SC NOC) / NDC (pharmacy)

Achondroplasia vs other short-stature class context FDA verified May 2026

Voxzogo is the only FDA-approved disease-modifying therapy for achondroplasia. Growth hormone is for a different patient population and a different mechanism.

Voxzogo is mechanism-unique among pediatric growth therapies. It is a C-natriuretic peptide (CNP) analog that binds the NPR-B receptor on growth-plate chondrocytes and antagonizes the downstream MAPK signaling that is constitutively activated in achondroplasia by the gain-of-function FGFR3 mutation. The result is restored endochondral bone growth at the growth plate. There is no biosimilar, generic, or alternative CNP-analog product on the US market.

Voxzogo is frequently confused with growth hormone (somatropin), which is a different drug class, treats different indications, and is generally ineffective in achondroplasia (the achondroplasia defect is at the cartilage growth plate, not in the GH-IGF1 axis). The table below disambiguates Voxzogo from the somatropin class and from other rare-disease pediatric growth therapies.

Dosing & weight-band math FDA label current

Daily SC injection. Dose is mcg/kg per FDA weight-band table. Recalculate when child crosses a weight band — expect frequent dose adjustments as the child grows.

Worked example — 18 kg, 5-year-old patient

Re-dosing as the child grows

• Re-weight at every visit (typically every 3 months for pediatric specialty visits)
• If the child crosses a weight band, the prescriber issues a new prescription with updated dose and (where applicable) new vial size
• Specialty pharmacy dispenses the updated vial; old-band vials are typically used up before switching
• Coordinate with BioMarin RareConnections for any rapid dose changes
• Growth chart documentation (Voxzogo-specific achondroplasia growth chart preferred) supports continued medical necessity

Required pre-initiation checks

• FGFR3 genetic test report showing pathogenic achondroplasia-causing variant (c.1138G>A or c.1138G>C)
• Radiograph documenting open growth plates (typically left hand / wrist for bone age; X-rays of long bones acceptable)
• Age ≥4 months (per 2023 FDA expansion)
• Documented current weight (drives dose)
• No conditions that contraindicate SC injection
• Baseline blood pressure (W&P: transient hypotension possible)
• Caregiver injection training visit scheduled

NDC reference FDA NDC Directory verified May 2026

BioMarin labeler 68135. Vial size is chosen to match the calculated daily dose — specialty pharmacy ships the appropriate vial.

Administration codes CPT verified May 2026

Voxzogo is SC; medical-benefit in-office administration uses 96372. Caregiver daily SC at home has no admin CPT.

Modifiers CMS verified May 2026

JZ — whole-vial use (default for Voxzogo)

Effective July 1, 2023, CMS requires JZ on claims for single-dose container drugs when no drug is discarded. Voxzogo ships in fixed-size single-dose vials (0.4, 0.56, 1.2 mg), but the daily dose is weight-based and almost never exactly matches a vial size. However, because Voxzogo vials are single-dose only and each vial is used per dose (the leftover cannot be re-used), the typical pattern is: reconstitute the full vial, administer the calculated mcg dose, discard the remainder. Some MAC contractors treat this as "no discard" (because the full vial was reconstituted as labeled) and require JZ as the default; others permit JW for the per-day partial-vial waste. Verify with your MAC.

JW — per-day partial-vial waste (situational)

If your MAC permits JW reporting for the partial-vial waste between the calculated mcg dose and the vial contents (e.g., 360 mcg administered from a 560 mcg vial = 200 mcg waste), bill JW for the wasted mcg on a separate claim line. Document vial NDC, lot number, administered mcg, and wasted mcg in the medical record. For pharmacy-benefit (specialty Rx) Voxzogo, modifier rules do not apply — the pharmacy claim is per vial dispensed, not per mcg administered.

Modifier 25 — situational

Use modifier 25 on the E/M code when a significant, separately identifiable E/M service is performed on the same day as a 96372 injection — relevant for the caregiver-training visit when extended E/M counseling is the primary service and the injection is incidental.

340B modifiers (JG, TB)

For 340B-acquired Voxzogo (pediatric Medicaid + 340B-eligible academic medical centers and children's hospitals are the typical scenario), follow your MAC's 340B modifier policy. Voxzogo is purchased through specialty distributors with 340B pricing where applicable.

ICD-10-CM diagnosis codes FY2026 verified May 2026

Q77.4 is the primary and essentially only correct primary code. Voxzogo is achondroplasia-specific.

Site of care & place of service Verified May 2026

Voxzogo is overwhelmingly a home daily SC self/caregiver injection drug. Pharmacy-benefit dispensing through specialty pharmacy bypasses medical-benefit POS rules entirely — the drug ships to the patient's home and the caregiver administers daily. Medical-benefit in-office administration is rare and typically limited to the caregiver-training visit.

Claim form field mapping Verified May 2026

CMS-1500 / 837P for the rare medical-benefit SC. NCPDP D.0 for pharmacy benefit (dominant pathway).

Medical-benefit claim (J3490 NOC) — CMS-1500 / 837P

Pharmacy benefit dispensing — NCPDP D.0 (dominant pathway)

Voxzogo is dispensed by a specialty pharmacy and adjudicated through the pharmacy benefit. The specialty pharmacy submits an NCPDP claim with the NDC, days supply (typically 30-day supply of daily vials), DAW code, and patient demographic data. The prescribing provider's office writes the Rx and supports the PA but does not submit claims for daily home SC Voxzogo in this pathway. Pediatric Medicaid pharmacy benefit follows the same NCPDP D.0 transaction set.

Form references: NUCC (CMS-1500) · NCPDP (D.0 pharmacy).

Payer policy snapshot Reviewed May 2026

Universal prior auth. FGFR3 genetic confirmation + open growth plate documentation universal. Pediatric Medicaid is the largest payer segment.

What to document for approval

• FGFR3 molecular genetic test report showing pathogenic c.1138G>A or c.1138G>C variant from a CLIA-certified lab
• Radiograph documenting open growth plates (typically left-hand / wrist for bone age) within 6–12 months
• ICD-10 Q77.4 (achondroplasia) as primary
• Patient age ≥4 months
• Current weight in kg (drives dose)
• Specialist prescriber (pediatric endocrinologist or geneticist preferred)
• Documented caregiver injection training plan
• For reauth: updated radiograph, updated weight, growth velocity since prior auth

Medicare reimbursement No permanent J-code Q2 2026

Voxzogo is pediatric — Medicare is almost never the primary payer. Medical-benefit Part B (rare) uses J3490 NOC.

Why Medicare almost never pays for Voxzogo

Voxzogo is approved for children ≥4 months with open growth plates. The drug is FDA-labeled to be discontinued at skeletal maturity — meaning the patient population aged out of pediatric coverage before potentially aging into Medicare. Medicare may apply only in the rare disabled-pediatric scenario (e.g., a child with achondroplasia on SSI / Medicare via SSDI before age 21), where it would be Part D. Otherwise, the payer mix is overwhelmingly commercial pediatric (parents' plans) and pediatric Medicaid.

Code history

• November 19, 2021 — FDA approval (children ≥5 yr with achondroplasia and open growth plates)
• October 20, 2023 — FDA label expansion to children as young as 4 months (major coverage event)
• Q2 2026 — no permanent HCPCS J-code; medical-benefit claims continue to use J3490 NOC with NDC documentation
• Watch for HCPCS quarterly updates — a permanent vosoritide J-code is anticipated as utilization grows but has not been assigned as of Q2 2026

Patient assistance — BioMarin RareConnections BioMarin verified May 2026

• BioMarin RareConnections: 1-866-906-6100 — central support hub for benefits investigation, PA, copay assistance, and patient/caregiver education for all BioMarin rare-disease products including Voxzogo
• Voxzogo Copay Program (commercial patients only): as low as $0 copay; annual benefit caps apply — verify current limits with RareConnections. Excludes Medicare, Medicaid, TRICARE, VA, CHIP, and other federal program patients.
• BioMarin Patient Assistance Program (BioMarin PAP): free drug for uninsured / underinsured patients meeting income limits (typically ≤500% FPL)
• Bridge Program / Free Trial: starter supply available for new starts pending coverage determination (eligibility criteria apply)
• Foundation backup: Patient Advocate Foundation Copay Relief Program (rare disease fund); HealthWell Foundation rare disease fund; NORD patient assistance — verify quarterly for open achondroplasia / rare-disease fund status
• Little People of America (LPA): lpaonline.org — community support, advocacy, and additional family resources for achondroplasia / skeletal dysplasia
• Web: voxzogo.com · voxzogohcp.com · biomarin-rareconnections.com

Common denials & how to fix them

Frequently asked questions

What is the HCPCS code for Voxzogo?

Voxzogo (vosoritide) has no permanent J-code as of Q2 2026. Medical-benefit claims for in-office subcutaneous administration use HCPCS J3490 (unclassified drugs) paired with the 11-digit NDC, the administered mcg, patient weight, and dose calculation documentation in the NTE segment. Most utilization, however, runs through the pharmacy benefit (specialty Rx) because caregivers administer daily at home; pharmacy claims use the NDC under NCPDP D.0 and do not require a J-code.

FGFR3 testing requirements?

Universal payer PA requirement. Submit the full molecular genetic test report from a CLIA-certified laboratory showing a pathogenic FGFR3 c.1138G>A or c.1138G>C heterozygous variant (the two variants that cause >98% of achondroplasia cases). The report must include molecular methodology (Sanger sequencing, NGS panel, etc.), the specific variant identified, and an interpretive statement consistent with achondroplasia. Phenotype-only descriptions, prenatal ultrasound findings, or "presumed achondroplasia" notes will not satisfy this requirement.

Open growth plate documentation requirements?

Universal. Submit a recent (within 6–12 months) radiograph — typically left-hand / wrist for bone age — with a radiologist or pediatric radiologist read confirming that the epiphyses (growth plates) are open and the patient has not yet reached skeletal maturity. Some payers will accept a long-bone X-ray (femur, tibia, humerus) instead of bone-age imaging. Annual reauth requires fresh imaging confirming growth plates remain open.

When should Voxzogo be discontinued (skeletal maturity)?

Voxzogo is discontinued when radiographs show fused epiphyses (epiphyseal closure / skeletal maturity) and no further linear growth is possible. This is typically late adolescence (girls ~14–16 years, boys ~16–18 years), but achondroplasia patients may reach skeletal maturity earlier or later than typical peers. Closure is the FDA-labeled discontinuation criterion and is the #2 cause of Voxzogo reauth denial.

How is the weight-based dose calculated?

Use the FDA weight-band table in the Voxzogo prescribing information. The table maps current body weight (in kg) to a specific mcg/kg dose and the appropriate vial size (0.4, 0.56, or 1.2 mg). Younger / lighter children receive higher mcg/kg doses; older / heavier children receive lower mcg/kg doses. Dose is recalculated whenever the child crosses a weight band. BioMarin RareConnections provides a dosing calculator and supports prescribers with weight-band verification.

Daily SC at home — how does billing work?

Daily home SC by caregiver is the standard pathway. Specialty pharmacy dispenses Voxzogo on a 30-day supply basis (30 single-dose vials per shipment) under the pharmacy benefit (NCPDP D.0). The caregiver reconstitutes the lyophilized powder with the provided diluent and administers the daily SC injection. The prescribing office does not submit claims for these doses. The only medical-benefit billing scenario is an in-office training visit where a dose is actually administered (E/M + 96372 + J3490 + NDC).

Voxzogo vs growth hormone — what's the difference?

Different mechanism, different indication, different patient population. Voxzogo (vosoritide) is a CNP analog that antagonizes downstream FGFR3-MAPK signaling at the growth plate, approved exclusively for achondroplasia in children ≥4 months. Growth hormone (somatropin: Norditropin, Genotropin, Humatrope, etc.) treats GH deficiency, idiopathic short stature, Turner syndrome, SHOX deficiency, Noonan syndrome, SGA without catch-up, Prader-Willi, and CRI — but not achondroplasia. Growth hormone is generally ineffective in achondroplasia because the defect is at the growth plate cartilage, not in the GH-IGF1 axis upstream. There is no overlap in clinical positioning between Voxzogo and somatropin.

Does pediatric Medicaid cover Voxzogo as primary payer?

Yes — pediatric Medicaid is the largest single Voxzogo payer segment in the US. EPSDT requirements obligate state Medicaid programs to cover medically necessary services for children, including disease-modifying therapy for achondroplasia. All 50 state Medicaid programs cover Voxzogo with PA as of Q2 2026. State-level PA criteria mirror commercial: FGFR3 mutation confirmation, open growth plates, age ≥4 months, specialist prescriber, weight-based dosing documented. Coordinate via BioMarin RareConnections for state-specific documentation requirements.

Off-label coverage for other skeletal dysplasias (hypochondroplasia, etc.)?

No. Voxzogo PA requests for hypochondroplasia, thanatophoric dysplasia, idiopathic short stature, or other skeletal dysplasias are not covered by any major US payer as of Q2 2026. The FDA label is achondroplasia-specific, and the FGFR3 variant must be the achondroplasia-causing c.1138G>A or c.1138G>C. Hypochondroplasia is caused by different FGFR3 variants (most commonly N540K) and is excluded from Voxzogo coverage. Counsel families accordingly.

BioMarin RareConnections enrollment — how does it work?

BioMarin RareConnections (1-866-906-6100) is the central hub for Voxzogo support. Enroll the patient at the time of prescription. RareConnections handles benefits investigation, PA submission and follow-up, copay assistance enrollment, specialty pharmacy coordination, caregiver training scheduling, ongoing adherence support, and reauth coordination. Enrolling at intake (not just for PA fights) materially shortens time-to-first-dose — typical RareConnections-coordinated start is 2-6 weeks vs 6-12 weeks for unsupported submissions.

What is the annual WAC cost of Voxzogo?

Approximately $320,000 per year WAC for typical pediatric dosing, with year-over-year variation as the child grows through different weight bands and vial sizes. Net price after BioMarin RareConnections support, commercial copay assistance, and pediatric Medicaid rebates is materially lower and varies by plan. Lifetime cost (4 months to skeletal maturity, ∼15–18 years of therapy) commonly runs to several million dollars per patient.

Source documents

1. FDA — VOXZOGO (vosoritide) Prescribing Information
   FDA-approved label (BLA 214938); 2023 supplement expanding age indication to ≥4 months
2. DailyMed — VOXZOGO label search
   Current SC label with weight-band dosing table
3. Voxzogo.com — patient / caregiver site
   BioMarin RareConnections program details, caregiver injection guide
4. Voxzogo HCP — provider site
   Dosing references, reimbursement guides, FGFR3 testing resources
5. BioMarin RareConnections
   Central support hub for benefits investigation, PA, copay, training
6. CMS — Medicare Part B Drug ASP Pricing File
   Q2 2026 quarterly file; no permanent J-code for vosoritide as of this quarter
7. CMS — HCPCS quarterly update file
   J3490 unclassified drugs descriptor; permanent code not yet assigned for vosoritide
8. CMS — JW Modifier and JZ Modifier policy
   Single-dose container reporting requirements (effective July 1, 2023)
9. FDA Press Announcement — Voxzogo initial approval (Nov 2021)
   First drug for the most common form of skeletal dysplasia (achondroplasia); Nov 19, 2021
10. BioMarin — FDA Approves VOXZOGO for Children Under 5 Years with Achondroplasia (Oct 20, 2023)
    sNDA expansion to pediatric patients of all ages with open epiphyses; supported by Phase 2 Study 111-206 in children <5 yr (data extends down to ~4.4 months)
11. Little People of America (LPA)
    Community advocacy and family resources for achondroplasia / skeletal dysplasia
12. NORD — Achondroplasia
    Disease overview, FGFR3 genetics, clinical course
13. FDA National Drug Code Directory
    All BioMarin labeler 68135 vosoritide NDCs
14. BioMarin Pharmaceutical — manufacturer
    Manufacturer (labeler 68135, US headquarters San Rafael, CA)

About this page

We maintain this page as a living reference. Medicare ASP pricing references are bound to our underlying CareCost data layer and refresh automatically when CMS publishes new quarterly files. Coding and policy content is reviewed at least quarterly and updated whenever a source document changes.

Found an error? Email hello@carecostestimate.com.

Refresh cadence

Reviewer

Change log

• May 22, 2026 — SME audit pass. Removed all references to a 0.8 mg vial (does not exist per current FDA label and DailyMed). NDC table reduced to actually-marketed vial strengths. Dosing weight-band notes updated to reflect partial-vial draw for school-age patients. sNDA expansion date corrected to Oct 20, 2023.
• May 22, 2026 — Initial publication. FDA approvals: Nov 19, 2021 (initial, ≥5 yr), Oct 20, 2023 (expansion to all ages with open epiphyses). No permanent J-code; medical-benefit SC uses J3490 NOC. CNP analog class context vs growth hormone (somatropin) documented. Payer policies: UHC, Aetna, Cigna/Express Scripts, Anthem/Carelon, BCBS, pediatric Medicaid (EPSDT). FGFR3 mutation confirmation + open growth plate radiograph are universal PA gates.

Methodology

Every claim on this page is sourced inline. Coding guidance reflects current CMS HCPCS conventions and the fact that vosoritide has no permanent J-code as of Q2 2026. Payer policies are read directly from each payer's published medical/pharmacy policy documents. We do not paraphrase from billing-software vendor blogs. The FGFR3 mutation + open growth plate gate is the determinative coverage lever for this drug and is made explicit in multiple sections rather than buried in a footnote.