Varicella-Zoster Immune Globulin conforms to the regulations of the FDA concerning biologics (see Biologics 1041
). It is a sterile 15 percent to 18 percent solution of pH 7.0 containing the globulin fraction of human plasma consisting of not less than 99 percent of immunoglobulin G with traces of immunoglobulin A and immunoglobulin M, in 0.3 M
glycine as a stabilizer and 1:10,000 thimerosal as a preservative. It is derived from adult human plasma selected for high titers of varicella-zoster antibodies. Each unit of blood or plasma has been found nonreactive for hepatitis B surface antigen by a suitable method. The proteins of the plasma pools are fractionated by the cold ethanol precipitation method. The content of specific antibody is not less than 125 units, deliverable from a vial containing not more than 2.5 mL solution. The unit is defined as equivalent to 0.01 mL of a Varicella-Zoster Immune Globulin lot found effective in clinical trials and used as a reference for potency determinations, based on a fluorescent-antibody membrane antigen (FAMA) method for antibody titration.