PI Perspective #17

December 1995     View PDF     En español

New Treatment for ITP

In March of 1995 the FDA approved Rh Pharmaceuticals, Inc.’s “WinRho SDTM,” a new form of Intravenous Immunoglobulin (IVIG), for treatment of HIV-related Idiopathic Thrombocytopenia Purpura (ITP.)

ITP is a condition in which the body destroys its platelets prematurely, probably because clusters of HIV fragments and associated antibodies bind to the platelets marking them for destruction by the spleen and other parts of the immune system. Platelets are a key factor in the body’s ability to form blood clots. ITP can cause excessive bruising, difficulty scabbing and even spontaneous internal bleeding; increasing the chance of infection and reducing the body’s ability to control blood loss.

Many treatments have been tested on ITP. IVIG has been one of the more successful and is thought to reduce the ability of the antibody-fragment clusters to bind to the platelets. Immunoglobulin (Ig) is harvested from the blood plasma of human donors, creating two problems with older forms of Ig; large quantities are required so treatment is expensive—three to four thousand dollars per infusion—and there is a slight chance of a donor passing on a viral infection. Infusions are required every several weeks, making standard IVIG prohibitively expensive and somewhat dangerous for long-term therapy.

WinRho SD donors are stimulated to produce Ig with especially high levels of specific antibodies so a smaller amount of the product is required. This reduces the cost per infusion by about half. Also, WinRho SD has been treated to inactivate any viral contamination, making it safer to use. On the down side, because the WinRho SD antibodies are so specific, it is not effective against ITP in people who are Rho negative, and may not be suitable for some pregnant women.

In the trials the FDA reviewed, WinRho SD was effective both in people who were on AZT and those who were not, and effectiveness had not decreased after six infusions. Side effects developed following 4% of the infusions, and included headaches, chills, and fever. Because of the specific antibodies that the product uses, anemia caused by hemolysis (destruction of red blood cells) can also be a problem and RBC levels should be monitored, especially in people with low hemoglobin. Suggested dosing is set at 250 IU (50mg/kg bodyweight), and the infusions take about three to five minutes, as opposed to the several hours required for other forms of IVIG.

Univax Biologics, Inc. markets the product in the United States with a hotline to provide information on third party coverage, state guidelines and possible individual financial assistance. The hotline number is 1-800-789-2099.