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What’s in a dose? Perhaps not what you think
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An area of the medication use process that may not be given much conscious thought by pediatric health care practitioners is the volumetric description and measurement of liquid dosages for infants and young children. Two studies published this year highlight this topic and its importance. As most medication products administered to infants and children are liquid dosage forms, expression of the volume dose in the medication order and its measurement by the parent or caregiver assume significant importance.
Incorrect dosing instruments
Yin and colleagues examined the association between volume measurement unit and medication errors committed by parents (n=287) whose children (aged younger than 9 years) were seen in two New York EDs, and prescribed daily liquid medications for durations of up to 14 days. Parents were interviewed by telephone and in person after completion of the prescribed medications. The primary outcome variable was medication error (knowledge of the child’s prescribed dose and error in dose measurement), and was defined as a difference of >20%. Medications prescribed included mostly antibiotic or corticosteroid liquid products.
Edward A. Bell
Nearly 40% of parents committed an error in dose measurement and 31.7% incorrectly stated their child’s medication dosage. When provided with several dosing instruments, such as oral dosing syringes, dosing cups or kitchen teaspoons/tablespoons, 16.7% of parents chose a kitchen spoon instead of a standard dosing device. The majority of medication orders (52.6%) were written with dosage units of teaspoon/tablespoon, and 80% of the medication product labels used teaspoon/tablespoon measurement units. Thus, nearly one-third of medication product labels were inconsistent with the medication order. Parents who reported the dose administered as teaspoon or tablespoon were significantly more likely to use a nonstandard dosing device, such as a kitchen teaspoon or tablespoon, and were more than twice as likely to commit an error in dose measurement.
Confusing descriptions
In an evaluation of 649 prescriptions of the most frequently prescribed liquid medications for children aged 12 years and younger dispensed from four community pharmacies in Philadelphia, volumetric measures from the prescription were compared with the label on the dispensed bottles. Sixty-eight percent of the prescriptions and 62% of the dispensed bottle labels utilized milliliters as the dosing unit. Teaspoonful dosing descriptions were used in 24% of prescriptions and 29% of bottle labels (Shah, 2014). Additional published studies have revealed similar findings, where parents and caregivers were not able to accurately determine and measure liquid medication doses for their children. These studies demonstrated that parents often used kitchen devices when measuring liquid medication doses. For example, one study revealed that more than 25% of parents confused the terms “teaspoonful” and “tablespoonful,” or described dosing as “a spoonful.” Such confusion over teaspoonful and tablespoonful could potentially lead to administration of 33% or 300% of the prescribed dose.
Liquid medication products intended for use in children that are available over-the-counter may be an additional source of confusion and error for parents and caregivers. Yin and colleagues demonstrated in a study published in 2010 that many liquid medication OTC products contain one or more inconsistent and confusing descriptions of dosing and dose measurement. These inconsistencies included differences in dosing directions and markings on the supplied dosing devices, and missing or superfluous dosing device markings, among others. The FDA has evaluated concerns about the potential for inaccurate use of OTC liquid products intended for use in children and has recently released recommendations for product improvement for manufacturers of these products.
Nearly 40 years ago, the Committee on Drugs of the American Academy of Pediatrics described the inaccuracies and dangers of using kitchen teaspoons for measuring liquid medication dosages. Kitchen teaspoon volumes can range from 2 mL to 9 mL, and thus may often not accurately measure a medically intended “teaspoonful” dose of 5 mL. Unintentional medication overdoses in children have been identified to occur not uncommonly, and they have resulted in severe injury or death in some cases (Tzimenatos, 2009). Recent recommendations put forth by multiple professional organizations include use of milliliters (mL) only (ie, not teaspoon or tablespoon) as the unit of measure for liquid medication prescribing and dosing. These organizations include the CDC, the AAP, the Institute for Safe Medication Practices, the US Pharmacopeia, the American Association of Poison Control Centers, and the American Society of Health-System Pharmacists.
Conclusions
Numerous published data have revealed that parents and caregivers can easily and unintentionally administer inaccurate volume doses of liquid medications to their children. Studies have demonstrated that when medication orders are given as “teaspoonful” or “tablespoonful,” parents are more likely to administer inaccurate doses, by using inappropriate dosing devices or by being confused over the amount to administer. Calls have been made by many professional organizations for prescribers to use mL only when prescribing liquid medications. Taking a few minutes to counsel and educate caregivers on the use of an appropriate dosing device and volume description can be very important to ensure therapeutic and safe pharmacotherapy. As published studies have shown oral dosing syringes to be most accurate, prescribers and pediatric health care practitioners should educate parents and caregivers on their appropriate use.
References:
Committee on Drugs, American Academy of Pediatrics. Pediatrics. 1975;56:327-328.
Paul IM. AAP News. 2012;33:10.
Shah R. J Pediatr. 2014;164:596-601.
Tzimenatos L. Clinical Toxicology. 2009;47:348-354.
Yin HS. Pediatrics. 2014;134:1-8.
Yin HS. JAMA. 2010;304:2595-2602.
For more information:
Edward A. Bell, PharmD, BCPS, is professor of pharmacy practice at Drake University College of Pharmacy and Health Sciences and Blank Children’s Hospital and Clinics, Des Moines, Iowa. He also is a member of the Infectious Diseases In Children Editorial Board. Bell can be reached at ed.bell@drake.edu.
Disclosure: Bell reports no relevant financial disclosures.