Pharmacies should Dispense Unit-Dose Syringes using the Most Appropriate Concentration
A wrong route error happened after an order for 2 mg of oral morphine was dispensed using a commercially available 15 mL bottle containing a 100 mg/5 mL (20 mg/mL) oral solution. The oral syringe that accompanies the 20 mg/mL morphine solution bottle has a mark for 5 mg as the lowest dose on the syringe scale (Figure 1). Because the 2 mg (0.1 mL) dose was not measurable using the provided syringe, a nurse prepared the dose using a 1 mL parenteral syringe. That allowed for the accidental connection of the parenteral syringe to the patient's intravenous (IV) line, and unfortunately, the oral solution was administered IV.
The practitioner who reported this event linked the error to not having a way to measure and administer doses under 5 mg using the accompanying oral syringe. He asked ISMP to advocate for adding "smaller markings" on the syringe. However, morphine 20 mg/mL solution is intended only for opioid-tolerant patients who would be receiving doses in line with the syringe markings or greater. For lower doses, an oral solution is available in a 2 mg/mL (10 mg/5 mL) concentration. Thus, we won't advocate for changes to the morphine 20 mg/mL syringes.
Although lack of a smaller dose marking on the syringe scale may have contributed to preparing the dose with a parenteral syringe, the way to minimize the risk of an error and patient harm is to use the appropriate concentration of oral solution. The pharmacy investigated obtaining the lower concentration from their wholesaler. In addition, it is important to use only oral or ENFit syringes when preparing oral or enteral medications. Using parenteral syringes to measure oral/enteral liquid medication doses can lead to wrong route errors.
Silicone-Free Syringes Required
BERINERT, a concentrate of C1 esterase inhibitor (human), is indicated for the treatment of acute abdominal, facial, or laryngeal hereditary angioedema attacks (a rare condition). The medication requires proper dosing, preparation, and administration; however, a crucial piece of information in the product labeling can easily be missed: the manufacturer requires silicone-free syringes for reconstitution and administration of the drug.
The product, packaged as a kit, contains a single-use Berinert vial, a 10 mL vial of sterile water for injection, a Mix2Vial filter transfer set, and an alcohol swab; however, a silicone-free syringe is not included. As the drug is very expensive and must be protected from light, it was kept in the original packaging and was not opened prior to use. The product was prepared using a syringe with silicone, and the drug was administered to the patient. According to the company, it is important to use silicone-free syringes because particulate matter or visible protein flakes may appear when siliconized syringes are used. As the syringe is not part of the Berinert kit, pharmacies and patients must purchase silicone-free syringes from one of four companies that sell this product:
* Air-Tite Products Co (HSW NORM-JECT Syringes)
* B. Braun (Injekt Syringes)
* West Pharmaceutical Services (Daikyo Crystal Zenith Luer Lock Syringes)
* Thomas Scientific (HSW NORM-JECT Luer Lock Syringes)
CSL Behring, the manufacturer of Berinert, does not recommend the use of a specific silicone-free syringe, and they have not tested the syringes listed above with Berinert. We believe the manufacturer should include a silicone-free syringe with the drug. Also, with this drug, the intention is for the patient/caregiver to prepare doses for self-administration at the onset of a hereditary angioedema attack. Thus, pharmacies that dispense this drug should provide one of the four syringes mentioned above for use in the hospital. Discharge planning/care management staff should ensure these syringes are available for patients after discharge.
Syringes with Trailing Zeros
A pharmacist was completing a medication history and education session with a patient who used injectable methotrexate for psoriasis. The patient stated that she draws her methotrexate injection "up to the 10" on the syringe, but she did not know the dose in milligrams. The patient was using a 25 mg/mL injectable product, so 10 mL (250 mg) would have been too high of a dose for psoriasis, which is typically 10 to 25 mg once weekly. Upon further probing, the patient confirmed she draws the medication "up to the little 10." The pharmacist considered the possibility that the patient had been using an insulin syringe, as this is the only type of small syringe that has markings for whole numbers including a "10." This was also concerning. If the patient had been withdrawing methotrexate up to the "10 units" mark on an insulin syringe, this would have been only 0.1 mL (2.5 mg) of methotrexate, which would have been an underdose. The pharmacist contacted the dispensing pharmacy, which confirmed that they had dispensed tuberculin (TB) syringes to the patient. The pharmacist noticed online that some TB syringe scales use a trailing zero after the decimal point (i.e., 1.0 for 1 mL), and a few even failed to include a leading zero before a decimal point (e.g., .1, .2, .3) (Figure 2).
Fortunately, this patient had been drawing up the correct 1 mL amount (25 mg) but thought she was drawing the medication up to the "10," as she did not see the decimal point in the "1.0" syringe marking. This could have resulted in a serious medication error if the pharmacist had entered "10 mL" into the patient's record during medication reconciliation, or if the patient had indeed been taking the wrong dose based on confusion with the markings on the syringe. The pharmacist was able to counsel the patient regarding the correct dose. For decades, ISMP has recommended avoiding trailing zeros and including leading zeros for decimal doses, and we recently began repeating this recommendation to various manufacturers in reference to their syringes.