5 WARNINGS AND PRECAUTIONS
Serious immune-mediated reactions have been reported with the use of ATGAM. Clinical signs associated with anaphylaxis, other infusion associated reactions, and serum sickness have been reported.
Discontinue ATGAM if anaphylaxis occurs. A systemic reaction such as a generalized rash, tachycardia, dyspnea, hypotension, or anaphylaxis precludes any additional administration of ATGAM.
To identify those at greatest risk of systemic anaphylaxis, skin testing potential recipients is strongly recommended before commencing treatment. A conservative, conventional approach would first employ epicutaneous (prick) testing with undiluted ATGAM. If the subject does not show a wheal ten minutes after pricking, proceed to intradermal testing with 0.02 mL of a 1:1000 v/v (volume/volume) saline dilution of ATGAM with a separate saline control injection of similar volume. Read the result at 10 minutes: a wheal at the ATGAM site 3 or more mm larger in diameter than that at the saline control site (or a positive prick test) suggests clinical sensitivity and an increased possibility of a systemic allergic reaction should the drug be dosed intravenously.
The predictive value of this test has not been proven clinically. Allergic reactions such as anaphylaxis have occurred in patients whose skin test is negative. Also, skin testing done as described above will not predict for later development of serum sickness. In the presence of a locally positive skin test to ATGAM, serious consideration to alternative forms of therapy should be given. The risk to benefit ratio must be weighed. If therapy with ATGAM is deemed appropriate following a locally positive skin test, treatment should be administered in a setting where intensive life support facilities are immediately available and a physician familiar with the treatment of potentially life threatening allergic reactions is in attendance.
5.2 Transmissible Infectious Agents
Because ATGAM is made from equine and human blood components, it may carry a risk of transmitting infectious agents, e.g., viruses, and, theoretically, the Creutzfeldt-Jakob disease (CJD) agent.
No cases of transmission of viral diseases or CJD have been associated with the use of ATGAM.
All infections suspected by a physician possibly to have been transmitted by this product should be reported by the physician or other healthcare provider to Pfizer, Inc. at 1-800-438-1985.
Monitor patients for concurrent infection. Some studies have suggested an increase in the incidence of cytomegalovirus infection in patients receiving ATGAM.
Do not administer live vaccines to patients about to receive, receiving, or after treatment with ATGAM. Concomitant administration of ATGAM with live virus vaccines carries a potential of uncontrolled viral replication in the immunosuppressed patient. There is insufficient information to fully define the extent of the risk, or the period of time during which the risk exists. If administered, live viruses may interfere with ATGAM treatment.