Last updated: September 5, 2026
Rho(D) immune globulin intravenous (human), marketed in the United States primarily as WinRho SDF, is a mature plasma-derived biologic used for Rh isoimmunization prevention and immune thrombocytopenic purpura (ITP). Its commercial outlook depends more on donor-plasma supply, obstetric volumes, hospital purchasing, reimbursement, and manufacturing continuity than on patent exclusivity.
WinRho SDF has no conventional small-molecule generic pathway, no meaningful Orange Book patent cliff, and no publicly disclosed product-level revenue base. The principal competitive risks are supply interruption, replacement by other anti-D products in obstetrics, and the potential development of a follow-on or biosimilar anti-D product.
What is Rho(D) immune globulin intravenous (human)?
Rho(D) immune globulin is a human plasma-derived immunoglobulin containing antibodies against the RhD antigen. It prevents RhD-negative individuals from becoming immunized after exposure to RhD-positive red blood cells.
WinRho SDF is the principal product associated with the generic name “Rho(D) immune globulin intravenous (human)” in the United States. Its labeled uses include:
- Prevention of RhD alloimmunization in non-sensitized RhD-negative patients.
- Treatment of ITP in RhD-positive, non-splenectomized patients.
The ITP indication differentiates WinRho from many obstetric anti-D products. In ITP, antibody-coated red blood cells are cleared in the spleen, reducing platelet destruction. The mechanism creates a clinically useful alternative to corticosteroids, intravenous immunoglobulin, thrombopoietin receptor agonists, and splenectomy in selected patients.
FDA approval for WinRho SDF dates to 1995. The product is regulated as a biologic under a biologics license application rather than as a conventional chemical drug application (U.S. Food and Drug Administration [FDA], 2023a).
What is the FDA regulatory status of WinRho SDF?
WinRho SDF remains an FDA-approved prescription biologic. The product is associated with BLA 103915 and is manufactured from human plasma.
| Regulatory item |
Status |
| Product |
WinRho SDF |
| Active ingredient |
Rho(D) immune globulin human |
| Dosage form |
Sterile injectable solution |
| Regulatory pathway |
Biologics license application |
| U.S. approval |
1995 |
| Primary indications |
RhD alloimmunization prevention; ITP |
| Manufacturing basis |
Human plasma-derived immunoglobulin |
| Orange Book status |
Not the principal reference; biologics are tracked through FDA biologics systems |
| Purple Book relevance |
Yes, for reference-product and biosimilar tracking |
| FDA exclusivity position |
Original biologic exclusivity has expired |
The label carries serious warnings concerning intravascular hemolysis, hemolytic anemia, renal impairment, disseminated intravascular coagulation and acute renal failure. These risks limit use in certain ITP patients and increase the importance of patient selection and post-administration monitoring (FDA, 2023b).
When does Rho(D) immune globulin lose exclusivity?
WinRho’s regulatory exclusivity has already expired. Because the product was approved in 1995, the 12-year reference-product exclusivity period created by the Biologics Price Competition and Innovation Act did not apply retroactively in a commercially meaningful way.
The product does not face a conventional Hatch-Waxman patent expiration event comparable to a small-molecule medicine. Market entry would require a competing biologic, licensed plasma-derived product, or potentially a biosimilar or interchangeable product, depending on the FDA pathway and product characteristics.
Does WinRho SDF have an Orange Book patent?
No conventional Orange Book patent strategy is central to WinRho SDF. The Orange Book primarily covers approved drug products submitted through new drug applications. WinRho is a biologic licensed under a BLA. Relevant regulatory and exclusivity information is therefore more likely to appear in FDA biologics records and the Purple Book than in the Orange Book (FDA, 2024a).
Publicly available information does not establish a significant active composition-of-matter patent estate uniquely protecting WinRho SDF. Any remaining intellectual-property protection is more likely to involve manufacturing know-how, formulation details, process controls, analytical methods, trade secrets, and regulatory experience.
How many patents cover Rho(D) immune globulin intravenous (human)?
No reliable public record establishes a material portfolio of active, product-specific patents that would block competition with WinRho SDF.
The relevant protection categories are:
| Protection category |
Commercial significance |
| Antibody composition patents |
Limited for an old polyclonal plasma-derived product |
| Manufacturing patents |
Potentially relevant to purification, viral clearance, stabilization and yield |
| Formulation patents |
Potentially relevant to concentration, excipients and shelf life |
| Method-of-use patents |
Limited because Rh prophylaxis and ITP uses are established |
| Trade secrets |
High practical importance for process consistency and quality control |
| Regulatory know-how |
High importance in plasma sourcing, lot release and pharmacovigilance |
For this product class, manufacturing execution can create a stronger practical barrier than patent claims. A competitor must establish reliable plasma collection, donor screening, fractionation, purification, viral inactivation or removal, potency testing, sterility, stability and lot consistency.
What formulations are protected by Rho(D) immune globulin products?
WinRho SDF is a liquid injectable immunoglobulin formulation. Product differentiation is based less on a novel delivery system than on concentration, excipient composition, route of administration, stability and manufacturing quality.
Competing anti-D products include:
- WinRho SDF, associated with Sandoz historically and later commercialized in the United States by Saol Therapeutics.
- RhoGAM and MICRhoGAM, associated with Kedrion Biopharma.
- Rhophylac, associated with CSL Behring.
- HyperRHO, associated with Grifols.
The products are not automatically interchangeable. Differences can involve antibody concentration, dose presentation, route of administration, preservatives, stabilizers, packaging, administration instructions and approved indications.
Is there an oral or long-acting competitor?
There is no established oral anti-D substitute. The class remains dependent on injectable human immunoglobulin. Research into engineered anti-D antibodies and alternative prophylaxis technologies could eventually affect the market, but commercial products must match the established clinical performance and safety profile of plasma-derived therapy.
Which companies compete with WinRho SDF?
The competitive structure differs by indication.
Obstetric market
In obstetrics, WinRho competes with RhoGAM, MICRhoGAM and Rhophylac. This market is relatively standardized. Hospitals, obstetric practices and blood banks often prioritize supply reliability, dose availability, contracting terms and established clinical protocols.
ITP market
In ITP, WinRho competes with therapies that do not rely on anti-D immunoglobulin:
- Intravenous immunoglobulin.
- Corticosteroids.
- Anti-D alternatives where available.
- Rituximab.
- Eltrombopag.
- Romiplostim.
- Avatrombopag.
- Fostamatinib.
- Splenectomy in selected patients.
WinRho’s ITP opportunity is constrained by the requirement that patients generally be RhD-positive and non-splenectomized. The risk of hemolysis further limits broad adoption.
What is the financial trajectory for Rho(D) immune globulin intravenous (human)?
Public companies do not generally report WinRho SDF revenue as a separate line item. Product-level sales, gross margin, pricing and contribution profit are therefore not publicly measurable with precision.
The financial trajectory is best described as mature and supply-sensitive rather than growth-driven.
| Financial driver |
Expected effect |
| Birth volumes |
Supports baseline obstetric demand |
| RhD-negative population |
Defines the addressable prophylaxis population |
| Pregnancy screening |
Maintains recurring demand |
| Hospital contracts |
Pressures net pricing |
| Plasma collection costs |
Directly affect gross margin |
| Manufacturing yield |
Major determinant of unit economics |
| ITP prescribing |
Provides incremental demand but remains clinically restricted |
| Product shortages |
Can create short-term price and share volatility |
| Biosimilar entry |
Long-term downside risk to price and share |
| Patent expiry |
Limited immediate effect because the product is already mature |
The obstetric market supplies the more predictable revenue base. ITP use is smaller and more volatile because it depends on patient eligibility, safety concerns, physician preference and competition from non-immunoglobulin therapies.
Why is the product commercially durable?
Demand is supported by a continuing clinical requirement for Rh prophylaxis. RhD-negative pregnant patients carrying or potentially carrying an RhD-positive fetus remain a recurring treatment population. The product is embedded in obstetric protocols, hospital formularies and transfusion medicine workflows.
Commercial durability is weakened by several factors:
- The product is old and has limited ability to command premium pricing based on innovation.
- Several anti-D products compete in obstetrics.
- Hospitals can negotiate across suppliers.
- Plasma-derived manufacturing creates exposure to donor supply, testing, fractionation and logistics.
- The ITP indication carries clinically significant safety restrictions.
- Product shortages can shift market share rapidly.
What revenue exposure does WinRho create for its commercial owner?
WinRho’s revenue exposure is concentrated in a single mature biologic franchise. The owner benefits from recurring obstetric demand but carries manufacturing and supply-chain risk associated with plasma-derived products.
The business profile is therefore closer to a specialty hospital product than to a high-growth pharmaceutical asset:
- Revenue is recurring but not strongly patent protected.
- Pricing power is moderate to limited.
- Volume is linked to pregnancy and transfusion activity.
- Margin depends heavily on manufacturing scale and plasma economics.
- A supply disruption can damage revenue quickly.
- A competing approved anti-D product could take share without waiting for patent expiry.
For investors and licensors, the most important diligence items are net sales by indication, customer concentration, historical shortages, batch-release performance, plasma sourcing, manufacturing-site redundancy and reimbursement by payer channel.
Are there Paragraph IV challenges to WinRho SDF?
A conventional Paragraph IV challenge is not the expected route for WinRho SDF because Paragraph IV litigation concerns patents listed for drugs under the Hatch-Waxman framework. WinRho is a BLA-regulated biologic, and no central Orange Book patent dispute defines its competitive position.
A competitor would more likely pursue one of the following routes:
- A new biologics license application for a distinct anti-D product.
- A biosimilar application under section 351(k) of the Public Health Service Act.
- A plasma-derived product with sufficient comparability and clinical support.
- A product focused on a separate indication or formulation.
No material public Paragraph IV litigation is associated with WinRho SDF as the basis for market entry.
How strong is the patent estate for Rho(D) immune globulin?
The patent estate appears weak as a barrier to competition. The practical moat is stronger in manufacturing and regulatory execution than in patent scope.
Stronger protection areas
- Validated plasma sourcing and donor-screening systems.
- Fractionation and purification know-how.
- Viral clearance and safety controls.
- Product-specific potency assays.
- Stability and shelf-life data.
- FDA manufacturing history.
- Hospital and distributor relationships.
Weaker protection areas
- Broad composition patents for anti-D antibodies.
- Method-of-use patents for established Rh prophylaxis.
- Exclusivity based on product age.
- Conventional Orange Book patent litigation.
The asset can remain commercially useful despite a weak patent estate, but its value depends on execution rather than legal exclusivity.
What generic or biosimilar launch risks exist?
The near-term threat from an interchangeable biosimilar is limited by technical complexity. Anti-D products are polyclonal immunoglobulin preparations, and demonstrating comparable specificity, potency, pharmacokinetics, immunogenicity and clinical effect can be more difficult than for a single monoclonal antibody.
The principal launch risks are:
| Risk |
Assessment |
| Conventional generic launch |
Not applicable |
| Paragraph IV challenge |
Not applicable in the conventional sense |
| Biosimilar launch |
Technically possible but difficult |
| New plasma-derived competitor |
More practical than a conventional generic |
| Contracting-driven share loss |
Material in hospitals |
| Supply-driven substitution |
Material during shortages |
| Engineered anti-D replacement |
Long-term, not immediate |
A new competitor does not necessarily need to prove sameness to WinRho in the same manner as an ANDA applicant. It can develop an independently licensed anti-D product, although clinical, manufacturing and regulatory requirements remain substantial.
What patent litigation and settlement agreements affect WinRho?
No major publicly documented patent litigation or Paragraph IV settlement currently defines the WinRho SDF market. Commercial disputes are more likely to concern supply, distribution, product rights, quality, regulatory compliance or contracting than patent infringement.
Historical ownership and commercialization changes are more relevant than patent settlements. The product has moved through corporate ownership and commercialization arrangements, including the transfer of U.S. commercial rights from Sandoz to Saol Therapeutics. These transactions demonstrate that the asset can retain value as a specialty product after patent and regulatory exclusivity have ended.
How does WinRho compare with RhoGAM and Rhophylac?
| Attribute |
WinRho SDF |
RhoGAM/MICRhoGAM |
Rhophylac |
| Product class |
Human anti-D immunoglobulin |
Human anti-D immunoglobulin |
Human anti-D immunoglobulin |
| Primary commercial use |
Obstetrics and ITP |
Primarily obstetrics |
Primarily obstetrics |
| ITP positioning |
Yes |
Not the principal positioning |
Not the principal positioning |
| Regulatory type |
Biologic |
Biologic |
Biologic |
| Patent-driven differentiation |
Limited |
Limited |
Limited |
| Key competitive factor |
Dual indication and supply |
Brand recognition and distribution |
Global manufacturer scale |
| Main vulnerability |
ITP safety restrictions and supply |
Competitive contracting |
Supply and pricing pressure |
WinRho has a broader labeled use profile than the main obstetric competitors, but its ITP opportunity is narrower than the label alone suggests.
What is the outlook for the market?
The market should remain stable but mature. Obstetric demand provides a durable base, while ITP use adds incremental value without creating a high-growth trajectory.
The most likely commercial scenarios are:
Base case
WinRho retains a stable specialty position, with revenue tracking obstetric volumes, pricing discipline and supply performance. Growth remains low single digit or flat in real terms.
Upside case
A competitor experiences a shortage, WinRho secures favorable hospital contracts, or ITP prescribing expands in selected treatment settings. Share and revenue increase without major market expansion.
Downside case
A new anti-D product gains regulatory approval, pricing competition intensifies, plasma costs rise, or safety concerns reduce ITP use. Revenue declines through share loss rather than patent expiry.
Key Takeaways
- Rho(D) immune globulin intravenous (human) is a mature plasma-derived biologic, principally represented by WinRho SDF in the United States.
- FDA approval dates to 1995, and the product’s original regulatory exclusivity has expired.
- A conventional Orange Book patent cliff and Paragraph IV challenge are not central to the product’s market.
- The patent estate appears less important than manufacturing know-how, plasma supply and regulatory history.
- Obstetric prophylaxis is the core recurring market; ITP is a narrower supplemental indication.
- Product-level revenue is not publicly disclosed, preventing a precise historical sales curve.
- Competitive pressure comes from RhoGAM, MICRhoGAM, Rhophylac, HyperRHO and non-anti-D ITP therapies.
- The largest financial risks are supply interruption, pricing pressure, plasma costs and future biologic competition.
- A biosimilar or independently developed anti-D product could enter, but technical and regulatory barriers are substantial.
FAQs
Is WinRho SDF still FDA approved?
Yes. WinRho SDF remains an FDA-approved biologic for RhD alloimmunization prevention and selected RhD-positive, non-splenectomized patients with ITP.
Is WinRho interchangeable with RhoGAM?
No automatic interchangeability should be assumed. Products may differ in concentration, dosing, route, formulation, labeling and approved uses.
Does WinRho have a biosimilar competitor?
No FDA-approved biosimilar specifically replacing WinRho SDF is established in the public regulatory record as of the current reference period.
Why is WinRho used for ITP but RhoGAM is mainly used in pregnancy?
WinRho has a labeled ITP indication based on antibody-mediated clearance of Rh-positive red blood cells. Obstetric anti-D products are principally positioned for prevention of RhD alloimmunization.
What is the main investment risk for an anti-D immunoglobulin product?
The main risk is commercial and operational rather than patent-related. Plasma availability, manufacturing continuity, hospital contracting, safety monitoring and future biologic competition determine the product’s financial performance.
References
-
U.S. Food and Drug Administration. (2023a). WinRho SDF: Product information and biologics license application records. FDA Drugs@FDA.
-
U.S. Food and Drug Administration. (2023b). WinRho SDF prescribing information. FDA.
-
U.S. Food and Drug Administration. (2024a). Purple Book: Database of licensed biological products. FDA.
-
U.S. Food and Drug Administration. (2024b). Biologics Price Competition and Innovation Act of 2009. FDA.
-
Saol Therapeutics. (2024). WinRho SDF product information. Saol Therapeutics, Inc.
-
Kedrion Biopharma. (2024). RhoGAM and MICRhoGAM prescribing information. Kedrion Biopharma.
-
CSL Behring. (2024). Rhophylac prescribing information. CSL Behring.
