Drug Companies Working on Products to Reduce Severe GI Problems Among Opioid Users

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Individuals taking long-term opioids for chronic back pain suffer abundant gastrointestinal (GI) side effects, ones that often lead to the cessation of opioid therapy.
Two recent studies sponsored by GlaxoSmithKline illustrate both the prevalence and severity of GI problems related to long-term opioid use. And they identify a market that GlaxoSmithKline hopes to fill with a drug that can prevent the worst of these complications.
In one effort to characterize GI complications related to long-term opioid use for chronic pain of all, M. Lucero, MD, of Glaxo SmithKline and colleagues performed a structured review of 237 trials and studies on the use of opioids for pain of all types. “The literature indicated that opioid-induced gastrointestinal adverse effects, including constipation, abdominal pain/bloating, and reflux are among the major clinically significant issues in pain management,” according to Lucero et al. The review concluded that the elderly, and those in palliative care, were at highest risk of GI complications. (See Lucero et al., 2006.)
Constipation rates ranged from 5% to 58% in patients with chronic cancer pain and 16% to 49% among patients with noncancer pain. Opioid-related side effects caused changes in analgesic therapy in at least 10% of patients. However, more than 50% of patients reported their constipation to be moderate-to-severe—and an interference with their pain therapy.
In a second study, G. Irving, MD, et al. studied the prevalence of GI complications in a cohort of 522 subjects who were using oral morphine, or its equivalents, at doses of 30 mg or more per day. All had been recruited to the study because they complained of GI side effects. (See Irving et al., 2006.)
The subjects reported substantial GI problems: abdominal pain (65%), bloating (79%), intestinal gas (71%), decreased appetite (40%), gastroesophageal reflux (32%), and nausea (27%). But the most significant problems related to constipation, despite abundant use of laxatives and stool softeners.
“Novel therapies are needed to address these persistent opioid-induced gastrointestinal adverse effects,” according to Irving et al.
GlaxoSmithKline is investing substantial resources in an effort to identify such therapies. And in preliminary studies, the opioid receptor antagonist alvimopan seems to reduce GI complications among opioid users. Though users still reported a variety of GI side effects, so did those who took a placebo. (See GlaxoSmith Kline, 2006.
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