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ORLANDO -- Using diphenhydramine (Benadryl) in addition to conventional sedatives decreased pain and improved quality of sedation during colonoscopy, a researcher reported here.
Results from a randomized, double-blind study of more than 100 patients indicated that, compared with placebo, add-on diphenhydramine significantly improved mean sedation scores as assessed separately by physicians (mean 6.2 versus 5.3 on a scale of 1-7; P=0.0002) and nurses (5.6 versus 5.1; P=0.04), reported Salman Nusrat, MD, of Oklahoma Health Sciences Center in Oklahoma City.
Action Points
- Note that this study was published as an abstract and presented at a conference. These data and conclusions should be considered to be preliminary until published in a peer-reviewed journal.
Diphenhydramine also appeared to improve patient comfort without increasing the number of adverse events, he said during his Monday afternoon presentation at the .
Nusrat explained that as opioid use becomes more prevalent in the general population with the associated development of tolerance, patients can be less responsive to conventional opioid sedatives, making sedation a challenge. "Patient tolerance is important for successful and safe completion of colonoscopy and results in increased compliance and willingness to undergo repeat procedure," he said.
"Our results showed that, though the use of diphenhydramine did not decrease the dose of conventional sedative used, it did improve the quality of sedation as rated by the patient, nurses and the physicians," stated Nusrat.
Nusrat and colleagues randomized 119 patients at the Oklahoma City Veterans' Affairs Medical Center from July 2014 to November 2016. All patients used chronic opioids (defined as at least 5 mg of morphine or its equivalent at least 3 days per week for more than 3 months) and were scheduled to undergo colonoscopy. Those who were pregnant, had a history of colon resection, or severe cardiopulmonary disease were excluded.
In addition to receiving intravenous fentanyl and midazolam before the procedure, patients were assigned 1:1 to receive either 50 mg of diphenhydramine or placebo.
Quality of sedation was then assessed both categorically (inadequate, adequate, over-sedated) and quantitatively on a seven-point scale (spanning no effect to optimal sedation) separately by a physician and a nurse. Patients rated their pain on 10-point scales (1=no pain; 10=severe pain) and amnesia (1=complete memory; 10=no memory) the following day.
The researchers found that diphenhydramine improved patient scores for pain (mean 2.05 with diphenhydramine versus 3.09 for placebo) and amnesia (7.8 versus 6.5, respectively; P=0.047 for both comparisons), although the categorical assessment showed no significant difference between groups.
Hypotensive episodes were more common in patients in the placebo group. There were no statistical differences in induction time, procedure duration, or recovery time between the diphenhydramine and placebo groups.
A leading study limitation was that the majority of patients were older than 55 years and Caucasian males. Additionally, analysis was restricted to patients who were on chronic opioids and were undergoing outpatient colonoscopies.
Nusrat called for further studies to identify the optimal use of diphenhydramine as an adjunct to standard sedation.
Disclosures
The researchers reported no financial disclosures of interest.
Primary Source
World Congress of Gastroenterology at ACG2017
Nusrat S "Use of diphenhydramine as an adjunctive sedative for colonoscopy in patients on chronic opioids: a randomized controlled trial" ACG2017; Oral Abstract 17.