Preventing constipation caused by opioids in advanced cancer patients

OMAMA-study - Prevention of Opioid-induced Constipation in Patients With Advanced Cancer

PHASE4 · Amsterdam UMC, location VUmc · NCT05216328

This study is testing whether magnesium hydroxide can help prevent constipation caused by opioid pain medications in advanced cancer patients better than a standard treatment.

Quick facts

PhasePHASE4
Study typeInterventional
Enrollment330 (estimated)
Ages18 Years and up
SexAll
SponsorAmsterdam UMC, location VUmc (other)
Locations13 sites (Almere Stad, Flevoland and 12 other locations)
Trial IDNCT05216328 on ClinicalTrials.gov

What this trial studies

This study aims to evaluate the effectiveness of magnesium hydroxide compared to macrogol/electrolytes in preventing opioid-induced constipation (OIC) in patients with advanced cancer who are starting opioid treatment for pain management. Given that OIC affects a significant portion of cancer patients, the study will assess the tolerability and efficacy of these treatments in improving patient quality of life. Participants will be required to complete a questionnaire in Dutch to assess their symptoms and treatment outcomes. The study is designed to provide insights into a less commonly used laxative option that may be more acceptable to patients due to its neutral taste.

Who should consider this trial

Good fit: Ideal candidates are adults aged 18 and older with metastatic cancer who are beginning treatment with slow-release or transdermal opioids.

Not a fit: Patients with contraindications for laxatives, those using laxatives in the past four weeks, or those with severely impaired renal function may not benefit from this study.

Why it matters

Potential benefit: If successful, this study could provide a more tolerable treatment option for preventing constipation in patients undergoing opioid therapy for cancer pain.

How similar studies have performed: While macrogol/electrolytes has been proven effective for OIC, magnesium hydroxide has not been extensively studied for this purpose, making this approach relatively novel.

Eligibility criteria

Show full inclusion / exclusion criteria
Inclusion criteria:

In order to be eligible to participate in this study, a subject must meet all of the following criteria:

* Patients with metastatic cancer (≥18 years);
* Starting with slow release or transdermal opioids for pain;
* Able to complete a Dutch questionnaire. Previous treatment with opioids is allowed, if discontinued more than 4 weeks ago.

Exclusion Criteria:

A potential subject who meets any of the following criteria will be excluded from participation in this study:

* Patients with contra-indications for laxatives
* Use of laxatives during the last four weeks
* Severely impaired renal function (serum creatinine \>180 umol/l)
* Estimated life expectancy \<3 months

Where this trial is running

Almere Stad, Flevoland and 12 other locations

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.

View on ClinicalTrials.gov →

Conditions: Constipation, Opioid-Induced, Cancer, Palliative care, Cancer pain, Opioid-Induced Constipation, macrogol/electrolytes, magnesium hydroxide

Last reviewed 2026-05-15 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.