HONOLULU -- Commercial epinephrine autoinjectors contain needles
that are too short to reach the thigh muscles of a significant number of
children, results of a study show.
Penlike autoinjectors, which deliver epinephrine to at-risk
children and adults to treat symptoms of anaphylaxis, have become a
mainstay of rapid response to severe allergic reactions.
Past research showed that peak plasma concentration is attained far
more quickly (8 minutes vs. 34 minutes) when epinephrine is delivered
intramuscularly versus subcutaneously (J. Allergy Clin. Immunol.
2001;108:871-3).
The EpiPen Jr., designed for children who weigh less than 30 kg,
and the EpiPen, used for children and adults who weigh 30 kg or more,
contains spring-loaded needles that measure 1/2-inch and 5/8-inch,
respectively. Both devices are made by Dey, L.P. of Napa, Calif. At
press time, the company was preparing a response regarding the study.
Dr. Dawn S. Stecher, an emergency medicine physician at Phoenix
Children's Hospital, and her associates measured by ultrasound
linear array transducer the distance between the skin surface and the
vastus lateralis muscle (the largest part of the quadriceps muscle) in
the upper thighs of 128 girls and 128 boys in a healthy, convenience
sample of children between ages 1 and 12 years who presented to the
hospital's radiology department or emergency department for reasons
unrelated to the study.
The sample mostly comprised Hispanic and white children, with
roughly even numbers in each group, plus 4% African American subjects
and 4% of other race/ethnicity.
The children's ages ranged from 12 to 153 months, with the
average age of 7 years.
Seventy children (27% of the sample) were overweight, and 25 (10%)
were at risk for overweight, according to Centers for Disease Control
and Prevention guidelines.
The needle of the EpiPen Jr. would be too short to reach muscle in
19, or 12%, of 158 children who weighed less than 30 kg. Among the 98
children who weighed 30 kg or more, and would therefore be prescribed
the adult EpiPen, the needle length would be insufficient to reach
muscle in 29 children (30%).
In a logistic regression analysis, body mass index (BMI) was the
only independent predictor of whether the appropriate EpiPen needle
would reach muscle tissue, Dr. Stecher reported at the annual meeting of
the Pediatric Academic Societies.
"The needles on current EpiPen autoinjectors are not long
enough to reach muscle in a significant number of children," she
concluded in her oral presentation.
She recommended development of autoinjectors of "varying
needle lengths, based on BMI, to ensure that children are receiving
epinephrine properly."
Previous research has found that adult EpiPens are of insufficient
length to reach muscle in more women than men, regardless of BMI, but no
gender differences were seen in children, noted Dr. Stecher.
In response to a question from the audience, she said that she also
reviewed the measurement data with regard to Twinject, an autoinjection
system made by Verus Pharmaceuticals, but determined that its needles
are even shorter than those in EpiPen injectors.
Dr. Stecher reported no financial disclosures with regard to her
presentation.
BY BETSY BATES
Los Angeles Bureau
COPYRIGHT 2008 International Medical News
Group Reproduced with permission of the copyright holder. Further reproduction or distribution is prohibited without permission.
Copyright 2008 Gale, Cengage Learning. All rights
reserved. Gale Group is a Thomson Corporation Company.
NOTE: All illustrations and photos have been removed from this article.