Abstract
Acetaminophen is the most commonly used children’s medicine for relieving pain and reducing fever. 1 Unfortunately, accidental ingestions of liquid acetaminophen by young children are also common, contributing to over 2500 emergency department visits and 10 000 calls to poison centers annually.2,3 Flow restrictors, adapters that have narrow bottle openings or have reclosable seals, have been shown to reduce numbers and severity of ingestions. 3 In 2015, the Food and Drug Administration recommended that flow restrictors be added for all over-the-counter pediatric oral liquid products containing acetaminophen; however, not all flow restrictors may perform equally. 4 In 2019, the American Society for Testing and Materials (ASTM) published testing standards for flow restrictors (F3375-19) that mimic child actions (shaking [deceleration], squeezing [application of force], and sucking [negative pressure]). 5 We sought to determine if the amounts of medication released during ASTM flow restrictor testing vary for different acetaminophen products.
In June 2019, we purchased 11 brands of 4-ounce children’s acetaminophen (2 national brands, 2 mass merchant brands, 2 drug store chain brands, 2 grocery chain brands, 2 online retailer brands, and 1 bargain merchant brand). Two samples of each brand were weighed after the largest labeled dose (15 mL) was removed. ASTM procedures were followed for deceleration, application of force, and negative pressure testing, and samples were reweighed (Table 1). If there was >20% difference between the weight of released medication in the 2 trials, a third sample was tested and the closest 2 measurements were averaged. The average weight released was converted to mL, and t tests were used to compare the average amounts released.
Amount of Medication Released (mL) Based on ASTM Standard Test Method for Assessing Nonmetered Restricted Delivery Systems for Liquid Consumer Products.
Abbreviations: ASTM, American Society for Testing and Materials. SD, Standard Deviation.
Deceleration (“Shake”) Testing—affix the bottle horizontally to a 25-cm pendulum arm and allow to swing 90° from a horizontal position at 12 o’clock to a stop at an inverted position at 3 o’clock.
Application of Force (“Squeeze”) Testing—apply 39.6 ± 1.5 N with a 1-cm diameter lever for 5 seconds.
Application of Negative Pressure (Sucking) Testing—apply 21.6 ± 0.4 kPa of vacuum to an inverted container for 30 seconds.
Eighty-five samples were tested; 3 brands were found to have 2 different versions of flow restrictors. Products with earlier expiration dates all had flow restrictors with open holes, while more recent products had flow restrictors with elastomeric valves (Figure 1). Both flow restrictor versions were tested when available. Overall, an average of 2.2 mL (range = 1.2-3.1 mL) of medication was released with deceleration, 1.0 mL (range = 0.1-8.5 mL) of medication was released with application of force, and 7.5 mL (range = 6.2-9.0 mL) was released with negative pressure testing (Table 1). New elastomeric flow restrictor designs released less medication than discontinued open designs (P < .03). However, products with elastomeric flow restrictors did not always release significantly less medication than products with open holes.
Two versions of flow restrictors. Open hole (Panel A) and elastomeric (Panel B).
All tested brands of children’s acetaminophen products have flow restrictors, but flow restrictor design may not be the only factor that determines how much medication is released. One brand’s bottle was more malleable than all others tested and released significantly more acetaminophen on squeezing than all others.
Pharmacists and pharmacy technicians should be familiar with the types of flow restrictors and be able to answer caregiver questions and provide instruction on proper use. Pharmacy staff should periodically check products sold in their pharmacies for manufacturer updates in flow restrictor design. Although flow restrictors can mitigate the number and severity of accidental ingestions, reminding caregivers to keep medication out of children’s reach can help prevent them all together (cdc.gov/medicationsafety/protect/campaign.html).
Footnotes
Declaration of Conflicting Interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: The Product Quality Research Institute (PQRI) and the Consumer Healthcare Products Association (CHPA) provided funding for the purchase of the products tested.
