Wyeth has launched Relistor (methylnaltrexone bromide) for the treatment of opioid-induced constipation.


Methylnaltrexone bromide is a selective, peripherally acting antagonist of opioid binding at the mu-opioid receptor.

As a quaternary amine, the ability of methylnaltrexone to cross the blood-brain barrier is restricted, allowing methylnaltrexone to function in tissues such as the gastrointestinal tract, without impacting opioid-mediated analgesic effects in the central nervous system.

In one study1, 154 patients were randomised to receive a single dose of methylnaltrexone or placebo. Rescue-free laxation* within 4 hours occurred in 62% and 58% in the methylnaltrexone 0.15mg/kg and 0.30mg/kg groups, respectively. In the placebo group, 14% of patients had rescue-free laxation within 4 hours (p<0.0001).

In another study2 133 patients were randomised to receive methylnaltrexone 0.15mg/kg or placebo every other day for 2 weeks. In the methylnaltrexone group, 48% of patients had laxation within 4 hours after the first study dose, as compared with 15% in the placebo group.

* A bowel movement without the use of additional laxatives

View Relistor drug record

1. Poster presentation: Wellman C, Wilson, G, Israel, R. Methylnaltrexone in the treatment of opioid-induced constipation in patients with advanced illness: Results of two phase 3 trials.
2. Thomas J, Karver S, Cooney G et al. Methylnaltrexone for opioid-induced constipation in advanced illness. NEJM 2008: 358; 2332-43.

Further information: Wyeth

Want news like this straight to your inbox?
Sign up for our bulletins

Have you registered with us yet?

Register now to enjoy more articles and free email bulletins

Already registered?
Sign in

Register or Subscribe to MIMS

GPs can get MIMS print & online and GPonline for free when they register online – take 2 minutes, and make sure you get your free MIMS access! If you're not a GP, you can subscribe to MIMS for full access.

Register or subscribe

MIMS Dermatology

Read the latest issue online exclusively on MIMS Learning.

Read MIMS Dermatology

MIMS Adviser

Especially created for prescribing influencers.

Request free copy

Mobile apps

MIMS: access the full drug database and quick-reference tables on the go

MIMS Diagnosis and Management: concise information on signs and symptoms, investigations and diseases