Buttock fat hinders injectables, study

CHICAGO, Nov. 28 (UPI) -- Injectable drugs are not always reaching their target when delivered through the buttocks, according to a new study.

Researchers in Ireland said this week that in only 8 percent of women, and less than one third of men, a standard 1 1/4-inch hypodermic needle effectively engages the buttock muscle for intravenous delivery of a range of treatments including painkillers, vaccines and some cancer drugs.


"Our study has demonstrated that a majority of people - especially women - are not getting the proper dosage from injections to the buttocks," said study researcher Victoria Chan, registrar in clinical medicine at the Dublin-based Adelaide and Meath Hospital.

Speaking at the annual meeting of the Radiological Society of North America in Chicago, Chan told United Press International that the study of 50 patients highlighted yet more fallout from the nationwide obesity epidemic, as a standard hypodermic needle almost never reaches the muscle in people who are obese.

Specifically, of six people in the study who were underweight, computer-assisted tomography (CT) scans indicated that the needles reached the muscle in only half of these patients, she said.

What's more, in seven cases in which the patients were overweight, none of the standard needles reached the muscle layer.


"This a cautionary tale," said Michael Brant-Zawadski, medical director of radiology at Hoag Memorial Hospital Presbyterian, Newport Beach, Calif. "Perhaps the upper arm may be a better site than the buttocks in heavier people or in women, or perhaps longer needles are the way to get medicine where it needs to be."

Chan said studies are underway to evaluate how missing the muscle impacts medical outcomes.

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