Error-prone dose expression on label of unapproved drug, ascorbic acid, from Mylan

Problem: A pharmacist received an order for 500 mg of intravenous (IV) ascorbic acid for a patient with coronavirus (COVID-19). Although this product was on formulary at the hospital, it was rarely used prior to the COVID-19 pandemic, and the pharmacist had never dispensed it. (In COVID-19 investigational trials, IV ascorbic acid is being used in much larger doses [i.e., 10 or 12 g] after being added to an appropriate diluent, with the theory that it will hasten recovery.)

After selecting the available vial of ascorbic acid injection (Mylan), the pharmacist noticed that the principal display panel on the carton and vial label indicated that it contained 500 mg/mL (Figure 1). This is in conflict with USP <7>, which requires most medication labels to list the total amount of drug and volume in the vial (with the per mL amount below it in parentheses) on the principal display panel. She initially thought the entire vial contained 500 mg. However, the 50 mL vial contains 25 g (25,000 mg) of ascorbic acid. The Mylan website refers to this product as containing “25 g/50 mL (500 mg/mL),” but neither the carton nor the vial label indicates that the entire vial contains 25 g. The label does note that the vial contains 50 mL, but even this is in small font in the top right corner of the principal display panel (following the NDC number).

In this case, the pharmacist asked a pharmacy technician to prepare the 500 mg dose, which she mistakenly stated would require all 50 mL of the product in the vial. However, the hospital used an information technology system for compounding that specified to withdraw 1 mL from the vial for the 500 mg dose. Noting the discrepancy between the pharmacist’s verbal instructions and the compounding system instructions, the technician brought the vial back to the pharmacist to question how much to withdraw from the vial. The pharmacist then realized her mistake and that administering the entire vial contents (50 mL, 25 g) would have resulted in a 50-fold overdose.

Safe Practice Recommendations: If you are preparing or administering IV ascorbic acid, please be aware of the error-prone labeling on the Mylan product and on some other manufacturers’ ascorbic acid injection vials. The US Food and Drug Administration (FDA) was made aware of the labeling issue; however, the Mylan product is not FDA-approved. We have learned that Mylan has discontinued this unapproved product but some existing product may still be in the marketplace. If you have Mylan ascorbic acid injection, we recommend affixing an auxiliary label to the carton and/or vial indicating the total amount of drug in each vial. Pharmacies can purchase ascorbic acid injection vials from other manufacturers that safely express the total amount of drug in each vial on the label. ASCOR (ascorbic acid) from McGuff Pharmaceuticals is an FDA-approved product that lists the total amount (25,000 mg) contained in each 50 mL vial (Figure 2).