Condition category
Digestive System
Date applied
Date assigned
Last edited
Retrospectively registered
Overall trial status
Recruitment status
No longer recruiting

Plain English Summary

Not provided at time of registration

Trial website

Contact information



Primary contact

Mr Mark Bignell


Contact details

c/o Mr Rhodes' Secretary
Department of General Surgery
Norfolk and Norwich University Hospitals NHS Trust
Colney Lane
United Kingdom

Additional identifiers

EudraCT number number

Protocol/serial number


Study information

Scientific title

Naloxone hydrochloride SR gastro-resistant sustained release capsules as a treatment for functional constipation: a randomised, double-blind controlled trial in secondary care


Study hypothesis

The primary objective of this study is to assess the efficacy of Nalcol™ when used as an adjunct to usual laxatives in the treatment of patients with refractory chronic constipation. The null hypothesis states that there will be no improvement in the symptoms of constipation in those participants taking Nalcol™ compared to the placebo group.

Ethics approval

Cambridgeshire 1 Research Ethics Committee, ref: H09/0304/55

Study design

Single-centre double-blind randomised parallel-group study

Primary study design


Secondary study design

Randomised controlled trial

Trial setting


Trial type


Patient information sheet

Not available in web format, please use the contact details below to request a patient information sheet




This is a single-centre double-blind placebo-controlled study of the efficacy and safety of Nalcol™ given to patients with refractory constipation attending a specialist clinic. The study is principally a phase II trial of short-term (4 weeks) effect. It is suspected that Nalcol™ will have a moderate effect, and is used here as an adjuvant to regular laxatives.

The patients will all fulfil criteria for functional constipation (as above) and will have attended a specialist gastroenterology or colorectal clinic at the Norfolk and Norwich University Hospital. They will have undergone investigation for their constipation with barium enemas and also transit studies and their basic management, including dietary and lifestyle advice and modification of laxatives, will have been instigated.

The key treatment phase (Period 2) will last 4 weeks and data over 4 weeks of treatment will be available. Two weeks of pre-treatment data will be collected during the screening period before randomisation (Period 1). This will allow an assessment of patient suitability and health to ensure that the inclusion criteria are met and permit examination with a rigid sigmoidoscope to obtain a rectal biopsy and stool sample. This initial period will ensure short-term symptom stability and confirm patient compliance with diary completion. It will allow secondary analyses comparing pre-treatment and treated symptom scores and quality of life (QoL) data. A final phase of 4 weeks (Period 3) will allow all patients in the trial to evaluate the treatment and provide further observation over a more prolonged duration.

Nalcol™ is given to relieve symptoms, which may be variable from day-to-day. The tolerability of Nalcol™ tablets is expected to be comparable to that of commonly dispensed stimulant laxatives; with no significant systemic side effects. It is known that 10 mg, twice a day is effective in increasing gut motility in normal subjects and a group of patients have taken 40 mg daily and occasionally up to 60 mg daily for severe symptoms. 40 mg daily has therefore been chosen to be given to patients in this trial because of the very troublesome symptoms of constipation from which they suffer.

Intervention type



Phase II

Drug names

Naloxone hydrochloride (Nalcol™)

Primary outcome measures

Comparison of the responders during Period 2 of the study (weeks 3 - 6) in the treatment group and those in the placebo group. Response is defined as those participants who give an assessment of 'satisfactory improvement' on at least 50% of occasions over the 4-week trial period (Period 2) to the global question on the diary card.

Secondary outcome measures

1. Comparison of stool frequency and type, laxative use, Patient Assessment of Constipation Symptoms (PAC-SYM), and Patient Assessment of Constipation Quality of Life Questionnaire (PAC-QOL) between treatment and placebo groups during Period 2 of the study. PAC-SYM will be used to provide an overall symptom score; but each component will also be analysed separately to identify changes to individual symptoms. Comparison will be made between the pre- and post-trial transit study as an objective marker of a reduction in transit time.
2. Graphical representation of the temporal changes in stool frequency and type and analysis to assess any drop-off of effect after 8 weeks of use in those receiving Nalcol™ for 8 weeks or in the whole group
3. A comparison of pre-treatment versus treatment symptom levels in the whole (n = 120), i.e., Period 1 versus Period 3
4. Comparison of stool bacterial counts between the treatment and placebo groups in the selected subset after each Period

Overall trial start date


Overall trial end date


Reason abandoned


Participant inclusion criteria

1. Aged greater than 18 years
2. Male or female
3. Satisfy Rome III criteria for functional (slow transit) constipation
4. Symptoms not relieved by diet and laxatives

Participant type


Age group




Target number of participants


Participant exclusion criteria

1. Severe cardiac, renal or hepatic impairment
2. Severe psychiatric disturbance
3. Mental disorder preventing adequate informed consent
4. Dilatation of the bowel (megarectum or pseudo-obstruction)
5. Concomitant medication with drugs known to cause constipation
6. Known pregnancy, suspected pregnancy, or trying to conceive
7. Currently breastfeeding
8. Currently participating (or within 1 month) in any other study

Recruitment start date


Recruitment end date



Countries of recruitment

United Kingdom

Trial participating centre

c/o Mr Rhodes' Secretary
United Kingdom

Sponsor information


Norfolk and Norwich University Hospitals NHS Foundation Trust (UK)

Sponsor details

c/o Kath Andrews
Research and Development Office
Colney Lane
United Kingdom

Sponsor type




Funder type


Funder name

Norfolk and Norwich University Hospitals NHS Foundation Trust (UK) - research account (ref: E-31)

Alternative name(s)

Funding Body Type

Funding Body Subtype


Funder name

SLA Pharma AG (Switzerland) - provide active and placebo capsules

Alternative name(s)

Funding Body Type

Funding Body Subtype


Results and Publications

Publication and dissemination plan

Not provided at time of registration

Intention to publish date

Participant level data

Not provided at time of registration

Results - basic reporting

Publication summary

Publication citations

Additional files

Editorial Notes