PARASTOP - Paracetamol With Strong Opioids (PARASTOP)

February 23, 2026 updated by: Ørnulf Paulsen, Oslo University Hospital

PARASTOP - Paracetamol With Strong Opioids. A Randomized, Double-blind, Parallel-group Non-inferiority Phase III Withdrawal Trial of Paracetamol Versus Placebo in Conjunction With Opioids for Moderate to Severe Cancer-related Pain

Current guidelines recommend all people with cancer-related pain should be prescribed paracetamol, even those receiving high doses of strong pain killers (opioids) such as morphine. Although this has been shown in studies to be beneficial in other conditions, for instance dental work and after surgery, it has not been shown to further improve pain in people with cancer-related pain. Taking tablets is burdensome to patients and the study aims to determine whether the inconvenience of taking eight extra paracetamol tablets per day can be justified.

The study plans to show whether or not pain control is changed (non-inferior) when stopping paracetamol compared to continued use of paracetamol in people already taking strong pain killers for cancer-related pain. Voluntary participants who are taking a combination of paracetamol and a strong opioid are recruited to the study.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Completed

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
204

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Phase 3

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Contact Backup

  • Name: Siv Åshild Billington
  • Phone Number: +4797777857
  • Email: sivwii@sthf.no

Study Locations

  • Italy
      • Milan, Italy
        • Fondazione IRCCS Istituto Nazionale dei Tumori
  • Norway
      • Lørenskog, Norway, 1478
        • Akershus University Hospital
      • Oslo, Norway, 0424
        • OsloUH
      • Skien, Norway
        • Telemark Hospital Trust
      • Tromsø, Norway, 9019
        • Universitetssykehuset Nord-Norge
      • Trondheim, Norway, 7030
        • St. Olavs Hospital
      • Tønsberg, Norway, 3103
        • Vestfold Hospital Trust
      • Ålesund, Norway, 6026
        • Helse Møre og Romsdal
    • Drammen
      • Drammen, Drammen, Norway, 3004
        • Vestre Viken Hospital Trust
    • Førde
      • Førde, Førde, Norway, 6812
        • Førde Hospital Trust
    • Grålum
      • Sarpsborg, Grålum, Norway, 1714
        • Østfold Hospital Trust
    • Kristiansand
      • Kristiansand, Kristiansand, Norway, 4604
        • Sørlandet Hospital Trust
    • Stavanger
      • Stavanger, Stavanger, Norway, 4011
        • Stavanger University Hospital
  • Uganda
      • Kampala, Uganda
        • Makere University Hospital
  • United Kingdom
      • Edinburgh, United Kingdom
        • Edinburgh Cancer Research

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

18 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Participants must be ≥ 18 years of age inclusive, at the time of signing the informed consent.
  • ≥50 kg (due to paracetamol dosage)
  • Participants who are under palliative care or oncology service review
  • Diagnosis of metastatic cancer
  • Clinician-predicted life expectancy >2 months
  • Receiving daily regular strong opioids for cancer pain
  • Receiving stable scheduled opioid dose last 48 hours*
  • Receiving paracetamol 1 gram x three or four times a day for at least five days
  • Average pain intensity past 24 hours ≥ 2 and ≤ 7 (NRS 0-10)*
  • Able to take study drug/placebo as tablets
  • Able to comply with all study procedures

  • Capable of giving signed informed consent as described in Appendix 1 which includes compliance with the requirements and restrictions listed in the informed consent form (ICF) and in this protocol.

    • It is allowed to repeat procedure within the screening period without considering the participant being a rescreen

Exclusion Criteria:

  • History of allergy or hypersensitivity to any of the active substances or excipients in the study drug
  • Known severe liver or renal failure equivalent with CTCAE Grade 3 or 4* precluding continuation of paracetamol. (*Common Terminology Criteria for Adverse Events (CTCAE) Version 5.0)
  • Participants receiving subcutaneous, intravenous, intrathecal, or epidural opioid therapy
  • Participants receiving systemic anticancer treatment during the intervention period if they are anticipated to have increasing pain or other symptoms related to the treatment
  • Co-enrolment in other drug trials. Participants will not be enrolled in any other on-going interventional clinical trial. Study participants may be enrolled in non-interventional research (e.g. questionnaire, tissue collection studies)
  • Previously enrolled in this study
  • Pregnant or lactating women

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Quadruple

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Paracetamol
Paracetamol P.O. 500 mg 2 tablets four times a day for 7 days
Drug: Paracetamol
Paracetamol 500 mg
Other Names:
  • Acetaminophen
Placebo Comparator: Placebo
Placebo P.O. 2 tablets four times a day for 7 days
Drug: Placebo
Placebo

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
To establish whether placebo with strong opioids compared to paracetamol together with strong opioids provides non-inferior analgesia for cancer-related pain.
Time Frame: 7 days
Numeric Rating Scale 0-10: Average pain intensity past 24 hours
7 days

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
To establish whether placebo with strong opioids compared to paracetamol with strong opioids changes opioid related side effects.
Time Frame: 7 days
Opioid Side Effects Questionnaire
7 days
To establish whether placebo with strong opioids compared to paracetamol with strong opioids changes global rating of improvement.
Time Frame: 7 days
Patient Global Impression of Change
7 days
To establish whether placebo with strong opioids compared to paracetamol with strong opioids changes opioid requirements.
Time Frame: 7 days
Opioid consumption
7 days

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Oslo University Hospital

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
Sykehuset Telemark

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Ørnulf Paulsen, Telemark Hospital Trust

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
October 20, 2021

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
February 11, 2026

Study Completion (Actual)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
February 18, 2026

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
September 11, 2021

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
September 20, 2021

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
September 21, 2021

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
February 25, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
February 23, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
February 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • 180946

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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