Clinical Trial: Effects of Methylnaltrexone in Comparison to Naloxone on Loperamide-induced Delay of the Oro-cecal, Whole-gut and Colon Transit Time.

Study Status: Completed
Recruit Status: Completed
Study Type: Interventional

Official Title: Effects of Extended Release Methylnaltrexone Bromide (150 mg b.i.d.) in Comparison to Extended Release Naloxone Hydrochloride (20 mg b.i.d.) on Loperamide-induced Delay of the Oro-cecal, Whole-gut and

Brief Summary: The purpose of this study is to describe the effects of repeated-dose methylnaltrexone in preventing loperamide-induced delay of whole-gut, oro-cecal and colon transit time and to measure pharmacokinetics of methylnaltrexone and naloxone-3-glucuronide after oral administration of methylnaltrexone and naloxone.

Detailed Summary:

The increasing prevalence of opioid use and consequently, opioid-induced bowel dysfunction has prompted interest in identifying effective treatment options. Until now, the treatment of opioid-induced constipation (OIC) has been viewed as an extension of constipation in general. Traditional therapies for constipation such as bulking agents, stool softeners, stimulant laxatives, and osmotic agents are commonly utilized, but the effects of such therapies are nonspecific and are often generating diarrhea or cramps and some of these drugs cause severe side effects. Furthermore, these conventional measures are sometimes insufficient in some patients, especially those requiring increasing doses of opioids.

Opioid-induced constipation is predominantly mediated by gastrointestinal μ-opioid receptors. Selective blockade of these peripheral receptors might relieve constipation without compromising centrally mediated effects of opioid analgesia or precipitating withdrawal.

Naloxone is a competitive antagonist of opioid receptors inside and outside the central nervous system used as a solution for injection in the treatment of opioid overdose. When administered orally, it can reduce opioid-induced constipation due to a local action in the gut. It has a high first-pass metabolism, which is an advantage as the laxative effect can be achieved due to the local action in the gut without significant antagonism of the narcotic analgesic effect of opioid. In some patients, however, withdrawal symptoms or reduction of analgesia was seen.

Another way to prevent central actions is the use of opioid antagonists which cannot penetrate the blood-brain barrier such as methylnaltrexone and alvimopan. Their antagonism of μ-opioid receptors in the gastrointestinal tract seems to reverse opioid-
Sponsor: University Medicine Greifswald

Current Primary Outcome:

  • Whole-gut transit time (WGT) [ Time Frame: up to 7 days after administration of the study medication ]
    Whole-gut transit time (WGT) was assessed by counting the radio-opaque markers with different shapes (Colon Transit) at different time pints in the feces.
  • renal clearance (CLR) [ Time Frame: Blood sampling at 48, 49, 50, 50.5, 51, 51.5, 52, 52.5, 53, 53.5, 54, 54.5, 55, 55.5, 56, 57, 58, 60, 62, 64 h and urine sampling 48-60 h after administration of study medication ]
  • area under the curve of administration window (AUC0-12h) [ Time Frame: 48, 49, 50, 50.5, 51, 51.5, 52, 52.5, 53, 53.5, 54, 54.5, 55, 55.5, 56, 57, 58, 60, 62, 64 h after administration of study medication ]
  • maximum concentration at steady state (Css max) [ Time Frame: 48, 49, 50, 50.5, 51, 51.5, 52, 52.5, 53, 53.5, 54, 54.5, 55, 55.5, 56, 57, 58, 60, 62, 64 h after administration of study medication ]
  • minimum concentration at steady state (Css min) [ Time Frame: 48, 49, 50, 50.5, 51, 51.5, 52, 52.5, 53, 53.5, 54, 54.5, 55, 55.5, 56, 57, 58, 60, 62, 64 h after administration of study medication ]
  • average concentration of administration interval (Cav) [ Time Frame: 48, 49, 50, 50.5, 51, 51.5, 52, 52.5, 53, 53.5, 54, 54.5, 55, 55.5, 56, 57, 58, 60, 62, 64 h after administration of study medication ]
  • time of maximum concentration (Tmax) [ Time Frame: 48, 49, 50, 50.5, 51, 51.5, 52, 52.5, 53, 53.5, 54, 54.5, 55, 55.5, 56, 57, 58, 60, 62, 64 h after administration of study medication ]


Original Primary Outcome: Same as current

Current Secondary Outcome:

  • Oro-cecal transit time (OCT) [ Time Frame: 48, 49, 50, 50.5, 51, 51.5, 52, 52.5, 53, 53.5, 54, 54.5, 55, 55.5, 56, 57, 58, 60, 62, 64 h after first administration of study medication ]
    Oro-cecal transit time (OCT) was defined as the first appearance of sulfapyridine in the plasma (cut of >100 ng/ml) after oral administration of 500 mg sulfasalazine immediate release tablets.
  • Colon transit time (CTT) [ Time Frame: up to 7 days after administration of the study medication ]
    Colon transit time (CTT) was derived as the difference WGT minus OCT.


Original Secondary Outcome: Same as current

Information By: University Medicine Greifswald

Dates:
Date Received: May 7, 2012
Date Started: May 2011
Date Completion:
Last Updated: May 9, 2012
Last Verified: May 2012