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   What is WinRho® SDF indicated to treat?

Immune Thrombocytopenic Purpura (ITP)

WinRho® SDF is recommended for the treatment of non-splenectomized Rho (D) positive:

• children with acute or chronic ITP,
• adults with chronic ITP, or
• children and adults with ITP secondary to HIV infection
• In clinical situations of ITP requiring an increase in platelet count to prevent excessive hemorrhage

Pregnancy and Other Obstetric Conditions
WinRho® SDF is recommended for suppression of Rh isoimmunization in non-sensitized Rho (D) negative women within 72 hours after spontaneous or induced abortions, amniocentesis, chorionic villus sampling, ruptured tubal pregnancy, abdominal trauma or transplacental hemorrhage or in the normal course of pregnancy unless the blood type of the fetus or father is known to be Rho (D)-negative. In the case of maternal bleeding due to threatened abortion, WinRho® SDF should be administered as soon as possible. Suppression of Rh isoimmunization reduces the likelihood of hemolytic disease in an Rho (D)-positive fetus in present and future pregnancies.

Transfusion
WinRho® SDF is also recommended for the suppression of Rh isoimmunization in Rho (D)-negative female children and female adults in their childbearing years transfused with Rho (D)-positive red blood cells or blood components containing Rho (D)-positive red blood cells.

   How does WinRho® SDF work in the treatment of ITP?

The exact mechanism of action of WinRho® SDF is not completely known. ITP (immune thrombocytopenic purpura) is an autoimmune disease in which patients make antibodies against platelets. Antibody-coated platelets are thus marked for rapid uptake and destruction by macrophages of the reticuloendothelial system via Fc receptors. It is believed that WinRho® SDF 's primary mechanism of action is "Fc-receptor blockade." WinRho® SDF is a hyperimmune serum with a relatively high percentage of antibodies to the "D" marker on red blood cells. The anti-D antibodies in WinRho® SDF bind to red blood cells. This complex blocks Fc receptors, thus sparing antibody-coated platelets.

   How effective is WinRho® SDF for the treatment of ITP?

The following is a summary of the clinical reports supporting the licensure of WinRho® SDF for the treatment of ITP:
In the treatment of childhood chronic ITP (24 patients), WinRho therapy had an overall response rate of 79% (19/24) with a mean peak platelet count of 229,400/mm³. In the treatment of childhood acute ITP (38 patients), WinRho therapy had an overall response rate of 84% (32/38) with a mean peak platelet count of 319,500/mm³. In the treatment of adult chronic ITP (24 patients), WinRho® SDF therapy had an overall response rate of 88% (21/24) with a mean peak platelet count of 92,300/mm³. In the treatment of ITP secondary to HIV infection (63 patients), WinRho® SDF therapy had an overall response rate of 90% (57/63) with a mean peak platelet count of 81,700/mm³.
(Reference: WinRho® SDF Prescribing Information.)

   WinRho® SDF is effective in Rh positive non-splenectomized patients with ITP. What about Rh-negative patients?

WinRho® SDF should not be administered to Rh negative or splenectomized patients as efficacy has not been demonstrated. Only 10% to 15% of the population is Rh negative. Rh status can be established by a simple blood test prior to therapy.

   How effective is WinRho® SDF for treatment of chronic ITP?

WinRho® SDF is an excellent treatment option for chronic ITP in adults and children. One study demonstrated that 79% of ITP patients responded to initial therapy, with some patients being maintained on WinRho® SDF for over 13 months. Of those continuing on maintenance therapy approximately 30% achieved remission or were stable without therapy at 13 months. (Reference: Bussel JB, et al. Intravenous anti-D treatment of immune thrombocytopenic purpura: analysis of efficacy, toxicity, and mechanism of effect. Blood. 1991;77:1884-1893.)

An initial dose of 50 micrograms/kg is recommended for patients with hemoglobin >10 g/dL. For those patients with hemoglobin levels less than 10 g/dL, a reduced dose of 25-40 micrograms/kg is recommended to minimize the risk of increasing the severity of anemia in the patient. If a patient has a hemoglobin level <8 g/dL, use WinRho® SDF with extreme caution. The dose should be administered as a single dose over 3 to 5 minutes (rate of injection = 300mcg/5-15 seconds) via IV infusion. All patients should be monitored to determine clinical response by assessing platelet counts, red cell counts, hemoglobin and reticulocyte levels.

NOTE: WinRho SDF must be given by intravenous administration for the treatment of ITP.

   What about subsequent therapy?

If subsequent therapy is required to elevate platelet counts, dosing should be tailored for an individual patient. An intravenous dose between 25 and 60 micrograms/kg is recommended. The frequency and dose used in maintenance therapy should be determined by the patient's clinical response by assessing platelet counts, red cell counts, hemoglobin and reticulocyte levels.

   How fast does WinRho® SDF increase platelet levels? How long does the effect last?

Platelet counts rise within 1 to 2 days and peak within 7 to 14 days after initiation of therapy. The duration of response varies from patient to patient. However, the average duration is approximately 29 days.

   How much protein is in WinRho® SDF?

The primary protein in WinRho® SDF is gamma globulin or antibodies. A 300-microgram vial of WinRho® SDF contains 300 micrograms of anti-Rho (D) antibody and less than 100 mg of total protein.

   How much IgA is in WinRho® SDF?

WinRho® SDF contains trace amount of IgA (less than 40mcg/mL).

   Does WinRho® SDF or any of the packaging components contain latex?

No.

   Does WinRho® SDF contain thimerosal?

No.

   Who should be contacted if there are additional questions regarding WinRho® SDF?

If you have additional questions, please call Cangene Corporation at 1-877-Cangene (1-877-226-4363)

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WinRho® SDF Canadian Package Insert: English (713K)

Canadian Monographs: English (315K) - French (268K)

Public Communication - Jan. 24, 2006: English or French