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05/24/2013 10:53 AM

New Constipation Drugs In Development

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I doubt there's a single member here who takes opioids who isn't familiar with the awful constipation that accompanies their use. Weirdly, although we tend to become tolerant to most of opioids' nasty side-effects, constipation is one we never do, so it's an ongoing problem for virtually all CRPS patients.

There have been various discussions about the best drugs to combat this, and my opinions are there. I wanted to highlight a couple of new anti-constipation drugs under development (and one relatively unknown agent), most of which work by a different mechanism than those on the market, and are targeted specifically to constipation caused by opioids.

One of these, naloxegol, is almost through Phase III trials, meaning an NDA (New Drug Application) will soon be filed, and it could be on the market relatively soon, assuming the FDA doesn't find a problem. It's being developed by AstraZeneca. Here's a Medpagetoday article about it, followed by its rather short article in Wikipedia:

Another is naldemedine, being developed by Shionogi, which has just completed Phase II trials successfully and is anticipated to get through Phase III with little trouble. A short summary is available at Wikipedia:

The last is an existing drug you hear little of for reasons coming up, called alvimopan (brand name Entereg). Due to possible side-effects, it's currently only administered in hospitals. As is often true, the best summary appears in

What do these agents have in common? They're generally called "peripherally-acting opioid antagonists". This means that their actions exist outside the brain, since they are, by design, unable to cross the blood-brain barrier [BBB]. Thus, they do not interfere with opioids' analgesic or other beneficial actions.

Thus, they antagonize the constipating action of opioids without compromising their analgesic activity. Interestingly, all of these agents have the structure of either naloxone or naltrexone, attached to a polar subunit that renders them incapable of crossing the BBB. Pretty clever, actually.

So, if you have yet to find an agent that works for you, there's hope on the horizon!


Post edited by: cfthb, at: 06/07/2013 04:46 PM


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