CareCost Vials
2 × 400 mg
1 billing unit = 10 mg
800 mg dose → 80 billing units
J0490 · belimumab
120 mg and 400 mg single-dose vials · JW/JZ waste rules may apply
Calculate this patient's units ↓Typical Benlysta dose: 10 mg/kg
The drug and dose carry into the estimate.
The estimate prices J0490 and the administration line for the patient’s plan. Then it shows what the patient owes and the copay help that fits.
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Patient owes, 800 mg
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37 payer price files · Commercial + Medicare · Copay and foundation status · Deductible, coinsurance and out-of-pocket math
Benlysta J0490 is billed in units of 10 mg: weight (kg) × dose (mg/kg) = dose in mg ÷ 10 mg/unit = billing units. Example, the label's 10 mg/kg dose: 80 kg × 10 mg/kg = 800 mg ÷ 10 = 80 billing units.
Benlysta ships in two vial sizes, 120 mg and 400 mg, and the mg drawn can exceed the mg administered. This page applies the fewest-vials rule: pick the combination that uses the smallest number of vials, even if that leaves some drug undrawn. Report any leftover as JW; use JZ only when nothing was discarded. A 700 mg dose still draws two 400 mg vials rather than one 400 mg plus three 120 mg vials, because two vials is fewer — real money, as the table below shows.
Medicare pays $58.333 per billing unit for J0490, effective for claims in Q4 2026:
$4,666.64 for the 80-unit example above, plus $67.14 for the 96365 administration line.
One 10 mg/kg schedule covers both indications and every age from 5 years, so weight is what moves the units below; the fewest-vials rule finds each patient's draw from the two available vial sizes.
| Patient | Weight | Dose | Units | Vials drawn | Modifier |
|---|---|---|---|---|---|
| Adult, default | 80 kg | 800 mg | 80 | 2 × 400 mg | JZ |
| Lower-weight adult | 70 kg | 700 mg | 70 | 2 × 400 mg (100 mg discarded) | JW |
| Higher-weight adult | 100 kg | 1,000 mg | 100 | 3 × 400 mg (200 mg discarded) | JW |
| Child, 5 years and older | 30 kg | 300 mg | 30 | 1 × 400 mg (100 mg discarded) | JW |
The label sets no maximum dose, so the calculator multiplies 10 mg/kg through at any weight; the J0490 MUE is 160 units (1,600 mg) a day, well above a single infusion at these weights. Only the 80 kg row draws two full vials with nothing left over. Every other row opens the fewest vials the fewest-vials rule allows rather than the least amount of waste — a 70 kg dose still draws two 400 mg vials instead of a 400 mg plus three 120 mg combination, and reports the difference on a JW line, as the next section works through.
JZ — no discarded drug from a single-dose container. JW — discarded drug from a single-dose container, reported on its own claim line.
J0490 × 80 JZ · 96365 × 1.
J0490 × 70 · J0490 × 10 JW · 96365 × 1.
96365 covers the initial hour of a therapeutic, prophylactic or diagnostic infusion. Every IV Benlysta dose is reconstituted, diluted and administered as a single 1-hour drip infusion, never a bolus or push, so the claim reports 96365 × 1 alone. 96366 (each additional hour) applies only once the infusion passes 90 minutes total, which a 1-hour drip does not reach unless it is slowed or held for a reaction.
Premedication given before the infusion is not itself infusion time. If a practice slows or holds the drip for a reaction, only the drip minutes count toward 96365/96366; the label sets no maximum dose, so the units line has no cap of its own, but the J0490 MUE is 160 units (1,600 mg) a day.
The schedule is fixed for both indications: 10 mg/kg IV at weeks 0, 2 and 4, then every 4 weeks, ; the label sets no stopping point. The subcutaneous 200 mg autoinjector and prefilled syringe run on a separate weekly schedule and bill to the pharmacy benefit, never this administration code or J0490.
Benlysta IV ships as a lyophilized powder in two single-dose vials: 120 mg/5 mL (NDC 49401-101-01) and 400 mg/20 mL (NDC 49401-102-01). Each vial is reconstituted with sterile water to an 80 mg/mL concentration, then diluted into a 250 mL bag of 0.9% sodium chloride, 0.45% sodium chloride or Lactated Ringer's (a 100 mL bag may be used for a patient at or under 40 kg) before the 1-hour infusion.
A subcutaneous 200 mg/mL product is also on the label, as a prefilled autoinjector (NDC 49401-088-01) or prefilled syringe (NDC 49401-088-42), dosed weekly — a pharmacy-benefit product, not buy-and-bill, and never a J0490 claim. See the FDA Benlysta label (BLA125370) for the full reconstitution and administration instructions.
J0490 is the HCPCS code for reference Benlysta (belimumab) administered intravenously. No belimumab biosimilar exists; the 200 mg subcutaneous autoinjector and prefilled syringe are the same molecule, billed to the pharmacy benefit, never a J0490 claim. The one priced IV alternative in this class is Saphnelo (J0491, anifrolumab-fnia, AstraZeneca), a fixed 300 mg dose for SLE only, priced separately from Benlysta's mg/kg rate. See the HCPCS hub for coding across the full family. The Medicare rate for every quarter is on the cost page →
80 billing units at the label's 10 mg/kg dose. Benlysta J0490 bills 1 unit per 10 mg, so 80 kg × 10 mg/kg = 800 mg ÷ 10 = 80 units, drawn from two 400 mg vials with nothing discarded.
Two 400 mg vials, drawing exactly 800 mg with nothing left over, billed JZ. A lower weight, such as 700 mg for a 70 kg patient, still draws two 400 mg vials under the fewest-vials rule and has to report the extra 100 mg on its own JW line: $583.33 of drug at the Q4 2026 rate of $58.333 per unit.
Either, depending on the draw. A dose that lands exactly on full vials, such as 800 mg from two 400 mg vials, bills JZ. A dose that leaves drug in an opened vial, such as the 700 mg draw above, bills the leftover on a JW line.
96365 alone. 96365 covers the initial hour of a therapeutic, prophylactic or diagnostic infusion, and Benlysta's label-directed 1-hour drip infusion fits entirely inside it. 96366 (each additional hour) only applies once the infusion runs past 90 minutes total, which a 1-hour drip does not do unless it is slowed or held for a reaction; time spent on premedication is not infusion time.
At a single rate for both indications: 10 mg/kg IV at weeks 0, 2 and 4, then every 4 weeks, for active systemic lupus erythematosus or active lupus nephritis on standard therapy, from 5 years of age. The label sets no maximum dose, so the calculator multiplies the ordered mg/kg through at any weight.
$58.333 per billing unit (per 10 mg), effective for claims in Q4 2026: $4,666.64 for the 80-unit example above, plus $67.14 for the 96365 administration line.
Data current: pricing Q4 2026 · payer policies Oct 2026
Sources: CMS ASP pricing files (Q4 2026); FDA-approved prescribing information (BENLYSTA label, revised August 2026, BLA125370); CMS single-dose container JW/JZ policy (effective July 1, 2023); 26 commercial payer medical policies (CareCost payer policy library); CPT codebook administration-code guidance.
Reviewed September 21, 2026 by Erin Rose, CareCost Estimate founder. Methodology →