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Ensure appropriate dosing instructions and devices are provided for injectable medications
Roger Selvage 1331

Ensure appropriate dosing instructions and devices are provided for injectable medications

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Medication Safety

Photo of medical syringe sealed in original packaging.

Institute for Safe Medication Practices, Horsham, PA

When patients are prescribed injectable medications to self-administer at home, it is critical that they receive education from both the prescriber and pharmacist on proper injection technique, with clear verbal and written instructions on the dose volume to measure and administer, and are provided appropriate syringes, needles, and ancillary supplies (e.g., alcohol swabs) to administer the dose.

In a recent case reported by a patient, many of these steps did not occur when they started a new injectable medication.

A patient received a prescription for methotrexate injection for the first time. The prescriber and pharmacy provided administration instructions in terms of the mg dose rather than the mL dose volume. The pharmacy dispensed vials of methotrexate injection (50 mg/2 mL) labeled with the directions to “Inject 2.5 mg subcutaneously once weekly for 2 weeks then increase to 5 mg once weekly. May increase up to 10 mg once weekly.” When the patient picked up the prescription, they were not offered counseling by the pharmacist.

At home, the patient initially interpreted the instructions on the pharmacy label to mean that they should begin treatment by injecting 2.5 mL (or >60 mg) of methotrexate.

The patient also realized the pharmacy did not provide syringes and needles to administer the methotrexate. The patient’s roommate, who happened to be a student pharmacist, helped interpret the instructions, provided the correct initial dose volume of 0.1 mL (and each subsequent dose increase—0.2 mL [5 mg] and 0.4 mL [10 mg]), and informed the patient that they would need to return to the pharmacy to obtain 1 mL syringes to measure and administer the medication.

At the time of a subsequent refill of the methotrexate prescription, the pharmacy dispensed 3-mL syringes with 1-inch needles. While the syringe had markings for each tenth of an mL, it would be difficult for any patient to accurately measure their current 0.4 mL dose much less their earlier doses of 0.2 mL or 0.1 mL. Also, a 1-inch needle is appropriate for I.M., not S.C. injections. S.C. injections require 1/2- to 5/8-inch long needles.

When prescribing and dispensing injectable medications for patients to self-administer, whether they come in a prefilled device (e.g., pen device) or a vial, it is critical that prescribers and pharmacists provide patient education and injection training. This includes how to use the device (e.g., syringe) to measure and administer the medication.

Use the teach-back method to verify that the patient understands, and can demonstrate, how to properly prepare and administer the medication. Ensure the patient instructions printed on the pharmacy label include the dose in the unit of measure used for administration, which in the above case would be mL. Printing only the mg dose or even both the mg and mL dose on the pharmacy label can increase the risk of confusion for the patient.

Dispense metric-only syringes, with needles of appropriate length and gauge for the route of administration, in volumes that most closely match the prescribed dose volume. Ensure the patient is provided with a sufficient quantity of syringes based on the frequency of injections and is educated on the appropriate single-use nature of syringes and needles to avoid syringe re-use and potential contamination of multiple dose vials. CDC’s One & Only Campaign, available at apha.us/OneAndOnly, offers resources to help educate patients. ■

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