Twice already, staff in one hospital used the contents from the 2 mL vial but confused the 100 mg/mL strength stated on the peel-off label as the total amount of drug in the vial. For a patient who was supposed to receive 150 mg, two vials were used to draw up a total of 3 mL, and 300 mg was administered in error.
The Institute for Safe Medication Practices (ISMP) supports the use of peel-off labels to facilitate syringe labeling in certain circumstances, such as with vaccines or in the OR where providers prepare doses from vials. However, expressing the drug strength two different ways can lead to errors. It creates a situation where the amount per mL is what is read, not the total amount of drug per container volume, as required of manufacturers in United States Pharmacopeia (USP).
ISMP contacted Merck, the drug manufacturer, to recommend either changing the way the concentration is expressed on the peel-off label so it's the same as the vial label, or eliminating the peel-off label altogether. Be aware that other products with peel-off labels may have similar issues.
New product, new storage requirements
Shingrix (zoster vaccine recombinant, adjuvanted), referred to as “RZV” by the CDC, was approved for use by the FDA last October. For over a decade, Zostavax (zoster vaccine live, or ZVL) was the only herpes zoster vaccine on the market and the medical community was accustomed to the storage and administration requirements for that vaccine. But Shingrix and Zostavax have different storage requirements, components/diluents, and routes of administration. For example, Shingrix is given I.M., and Zostavax is given subcutaneously.
Both components of the Shingrix vaccine, its lyophilized gE antigen component and its adjuvant suspension component, should be stored under refrigeration, both before and after reconstitution (see package insert for details). If the lyophilized component or its adjuvant suspension is improperly stored in a freezer, it must be discarded.
The storage requirements for Zostavax are different. The lyophilized vaccine (attenuated varicella-zoster virus) should be stored in a freezer; the manufacturer-supplied sterile water diluent can be stored in a refrigerator or at room temperature.
The product components aren't interchangeable. A system should be employed to ensure the Shingrix lyophilized component and adjuvant suspension vials are stored with one another to reduce the risk of using a diluent from another vaccine.
Healthcare professionals who manage vaccine programs or administer vaccines need to be aware of these important differences. For more information, review recommendations for use of herpes zoster vaccine from the CDC Advisory Committee on Immunization Practices published in Morbidity and Mortality Weekly Report, available at www.ismp.org/sc?id=3100. The American Pharmacists Association describes the differences in a handy table that can be accessed at www.ismp.org/sc?id=3102.Copyright © 2018 Wolters Kluwer Health, Inc. All rights reserved.