FDA Cuts Minimum Measles Antibody Potency Spec

FDA says it is reducing the minimum measles antibody potency specification for immune globulin (IG) products in response to declining titers of measles antibodies in plasma donors. In a letter to licensed IG manufacturers, the agency says that declining levels of measles antibodies in plasma are caused by a decrease in the number of naturally infected donors, who have higher sustained measles antibody levels that do vaccinated donors.

The letter says that manufacturers may request lowering the specification. “Over the past several years,” it says, “increasing numbers of IG product lots from different manufacturers have failed to meet the measles antibody specification…. If the trend of failing to meet this specification continues, we anticipate that an increasing number of IG lots will be rejected, possibly leading to product shortage.”

Instructions for submitting a request to lower the antibody specification are included in the letter.