The U.S. Food and Drug Administration has approved a new medication for opioid-induced constipation (OIC), a common side effect for patients who take narcotic pain relievers.
The drug, known generically as naloxegel, will be sold under the brand name Movantik. The once-a-day pill was developed by British drug maker AstraZeneca Pharmaceuticals (NYSE: AZN) and Nektar Therapeutics (NASDAQ: NKTR).
“The FDA approval of Movantik provides a new treatment option for adult patients with chronic non-cancer pain suffering from opioid-induced constipation, a common side effect of opioid therapy,” said Dr. Briggs Morrison, Executive Vice President and Chief Medical Officer, AstraZeneca.
Opioids work by blocking pain signals to the brain and central nervous system called opioid receptors. But when the opioids attach to receptors in the gastrointestinal tract, there’s a decrease in fluid absorption and constipation may occur.
A survey of over 2,400 women with chronic pain by National Pain Report found that 8 out of 10 who have taken opioids experienced constipation at some time. Over 40% said they were “always” or “usually” constipated by opioids.
“My constipation causes me to feel more unwell than I usually do. It causes loss of appetite, nausea, weakness. Fighting to have a bowel movement is downright painful. Now when I have an IBS (irritable bowel syndrome) attack, my intestines cramp and cramp and I am unable to relieve myself, it’s horribly painful,” wrote one woman.
“There have been episodes of constipation that have lasted 10-13 days when I could not have a bowel movement. During this time I try various laxatives which would not work or made me cramp up so bad I would end up lying on the bath room floors for hours,” wrote another.
“Many times I bow out of activities because I’m so uncomfortable for not defecating for three days,” wrote another survey respondent.
Over 60% of the women said constipation from opioids had reduced their quality of life and over 20% said they had stopped taking an opioid because of constipation.
“I stopped taking Vicodin because it was so rough on my system,” said one woman
“Because it’s the only thing that gives me (pain) relief, I have to stick with it. One of the reasons why I take it as seldom as possible is how painful the OIC can be,” said another.
You can see the full results of the “Women in Pain” survey by clicking here.
Movantik is based on the same active molecule as naloxone, a drug developed in the 1960s to counter the effects of opioid overdose.
The FDA is requiring a post-marketing observational study of Movantik to evaluate the potential risk of cardiovascular problems in patients taking the drug. Heart attacks have been associated with another OIC drug – Entereg – but an FDA safety panel recommended in June that large cardiovascular safety trials were not needed before similar drugs were approved.
In two Phase III studies of Movantik on over 1,300 patients with OIC, AstraZeneca said there were no “clinically relevant imbalances” in cardiovascular events between patients treated with Movantik and a placebo.
Movantik was shown to maintain the pain killing effect of opioids’ in the brain and block their effects in the bowels. Bowel movements increased in over 40% of the patients, and stomach pain and other discomforts decreased. The most common side effects in both trials were abdominal pain, diarrhea, nausea and flatulence.
“For patients taking prescription opioids for chronic pain, constipation is one of the most common and bothersome side effects, and these patients can experience sub-optimal relief from laxatives,” said William Chey, MD, Professor of Medicine at the University of Michigan Health System. “These results demonstrated the potential for naloxegol… to be a new treatment option as the studies showed rapid and sustained improvement for these patients, without compromising their pain management over the course of the trials.”
Movantik is expected to be available to patients in the first half of 2015. Although the approved labeling will say that Montivak has no risk for abuse or dependency, the drug is classified as a restricted Schedule II controlled substance because it is structurally related to noroxymorphone, which is an opioid. AstraZeneca has submitted a petition to “deschedule” Montivak to the Drug Enforcement Administration (DEA), which the agency is reviewing.
Over-the-counter laxatives, drinking more water and eating foods high in fiber – such as fruits and vegetables – can also help induce a bowel movement, but are only effective in about half of patients experiencing OIC.