Hazard Alert! Confusion between tetanusdiphtheria toxoid (Td) and tuberculin purified protein derivative (PPD) led to unnecessary treatment.

 

From the May 1, 2003 issue of MSA Acute Care Edition Newsletter

Recently, we heard about two cases where Td toxoid was inadvertently injected intradermally into groups of patients following physician orders for PPD skin tests. Aventis Pasteur manufactures both products. The reactions resulting from the Td injections were read as positive PPDs, and the patients were started on isoniazid (INH). The errors were discovered after staff noticed a cluster of “positive PPD skin tests.” Examination of the lot numbers on products thought to be PPD showed that they were Td (a good reason for recording vaccine lot numbers in patient records). INH was stopped on all of the patients after negative results upon retesting. Fortunately, no adverse reactions to INH therapy were noted. In a nearly identical case, 20 patients were given INH in error. When we checked our error database, we found additional errors dating back to September 2000. In one case, a patient developed cellulitis and may have suffered permanent scarring. The error was discovered when the infected site aroused suspicion. Similar packaging may have contributed to the errors. Aventis biological products are available in stylized, colorful cartons (photo in PDF version of newsletter). Although colors differ from product to product, the style itself may distract practitioners from reading the label correctly. Both drugs are available in cartons of the same size, even though the volume of the enclosed vial may differ, and both have a circle on the front label panel with the number “5” enclosed. On the PPD vial, the number indicates “5 TU” (tuberculin units), while on the Td vial, the number indicates “5 mL.” Both products are stored in the refrigerator, and may be located side by side. Lack of availability of Td in single-dose syringes also forces providers to purchase multiple-dose vials, further contributing to the problem. We have contacted Aventis to suggest a restyled label and FDA has been alerted to the problem. To avoid this error, purchase these products from different manufacturers whenever possible. Also remove Td (and other vaccines) from floor stock (if feasible) and have pharmacy dispense the product.