A novel, patient-controlled sublingual analgesic is as effective for postop pain as intravenous morphine, independent of body mass index (BMI), according to a study presented here at Obesity Week 2015.

With more and more patients undergoing surgery for obesity-related conditions, such as knee and hip arthroplasty, the physiological differences between obese and normal-weight patients may affect not only procedural analgesic requirements but also postoperative pain management, which is critical for prevention of complications.

A handheld, non-invasive patient-controlled analgesia product currently under US Food and Drug Administration (FDA) review for management of moderate-to-severe acute pain — the sufentanil sublingual tablet system — allows patients to self-administer sufentanil 15 mcg tablets with a 20-minute lockout period and may be well-suited for obese patients given their ability to self-titrate based on body weight and need.

Pamela Palmer, MD, AcelRx Pharmaceuticals, Inc., Redwood City, California, and colleagues used pain intensity difference from baseline as well as global assessment measures over 48 hours to assess the analgesic efficacy and safety of self-administered sufentanil 15 mcg tablets. They also analysed data from a phase 3 development program using the tablets to treat postoperative pain, including 2 randomised, placebo-controlled trials and 1 open-label, active comparator study (vs intravenous patient-controlled morphine) in major joint replacement or abdominal surgery.

The study randomised 606 patients to the tablets; of the patients, 341 were non-obese, 23% had a BMI of ≥30 to <35kg/m2, and 21% had a BMI ≥35kg/m2.

They primary efficacy endpoints were met across all studies with obese and non-obese demonstrating roughly equivalent analgesic responses. There was no difference in number of tablet doses needed to gain control over pain in the first hour or mean inter-dosing intervals over 48 hours, suggesting appropriate self-titration based on weight. Furthermore, adverse event profiles were similar across all body mass index sub-groups.

“With these obese patients we saw rapid onset of analgesia, we saw high efficacy compared to placebo, and we also saw a trend toward lower adverse events compared with [intravenous patient-controlled] morphine, which is the current standard-of-care for postoperative analgesia,” said Dr. Palmer.

She added that the onset of action being more rapid than intravenous morphine is a key result to take into account.

“The onset of action being more rapid than IV I think surprises everybody,” she said. “I’ve been working with the drug now for 10 years so it’s not becoming a surprise anymore, but this is a sublingual route of administration so it’s not invasive, and you know how difficult IV access can be in the obese patient. So being able to give them a non-invasive route — a postoperative analgesia that’s actually faster than intravenous morphine — is really a surprising part of our data.”

Obesity Week 2015 is sponsored by the American Society for Metabolic & Bariatric Surgery and the Obesity Society.

[Presentation title: Efficacy and Safety of the Sufentanil Sublingual Tablet System (SSTS) in Class I and II Obese Patients: The Effect of BMI on Analgesic Response. Abstract T-P-3144]