From the May 2009 issue

Mix-ups involving the expressions of volume, specifically confusion between milliliter and teaspoonful, continue to happen. We have written about these errors previously in this newsletter (www.ismp.org/Newsletters/ambulatory/archives/200604_1.asp). Unfortunately, it seems not much is being done to prevent these errors. Just recently, ISMP has learned of two more incidents. In the first, published in The Script, a publication from the California Board of Pharmacy, an 8-month-old child was prescribed NOVAHISTINE DH (dihydrocodeine, chlorpheniramine, phenylephrine), a cough and cold product. The pharmacist labeled the prescription with directions to “Give 1.5 teaspoonfuls by mouth every 6 hours” (equivalent to 7.5 mL) instead of 1.5 mL every 6 hours. In the second case reported in the Cape Cod Times, a 10-month-old child was dispensed the antibiotic solution cephalexin. The pharmacy-generated label, along with verbal instructions provided at the point-of-sale, incorrectly instructed the parent to administer three teaspoonfuls 3 times a day (equivalent to 15 mL) instead of 3 mL three times a day. Thankfully, in both cases, the mother of each child caught the error prior to giving any drug. It is time for the healthcare industry and practitioners to acknowledge this risk and make a change. Volume expression on prescriptions and pharmacy labels must be standardized to the metric system. ISMP calls on all pharmacies as well as pharmacy computer system and e-prescribing system vendors to take action now and remove and prevent the use of “teaspoonful” and other non-metric measures in all computer systems. This should include any mnemonics, speed codes, or defaults used to generate prescriptions and labels. Prescribers should express doses for oral liquids only in metric weights or volumes (e.g., mg or mL)—never by teaspoon or tablespoon. Double check the directions that appear on the pharmacy label against the original prescription. Take steps to ensure that patients have an appropriate device to measure volume in milliliters when a prescription for an oral liquid medication is dispensed. Coach patients how to use and clean these devices; use the teach back approach and ask patients to demonstrate their understanding.