Acute Post Operative PainIMAPSSNCT06659965
Intravenous Methocarbamol for Acute Pain After Spine Surgery
An observational study of Acute Post Operative Pain and Postsurgical Pain Management, run by The University of Texas Health Science Center, Houston at 1 site in United States.
Trial summary
The goal of this target trial emulation is to evaluate the impact of intravenous (IV) methocarbamol on postoperative pain and opioid use in adults undergoing elective spine surgery. Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Acute Post Operative Pain, Postsurgical Pain Management, Spine Surgery
- What is being tested?
- Intravenous Methocarbamol
- Type of treatment
- Injection or infusion
- How many people
- 1,270 participants
- Where
- 1 siteUnited States
- Study dates
- 1 Jan 2020to 30 Jun 2025
- Phase
- Observational
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Study population: The study population consists of adult patients undergoing elective spine surgeries at multiple hospitals within a large health system in Houston, TX. This includes individuals receiving surgical interventions for conditions such as degenerative disc disease, spinal stenosis, or other spinal pathologies that require procedures like ACDF, posterior spinal fusion, or laminectomy. Participants will be selected from those who receive perioperative care across various hospital settings within the health system, including postoperative management in the Post-Anesthesia Care Unit (PACU).
Who may be able to join
- 18 years of age or older
- Undergoing one of the following three elective spine surgeries: (i) Anterior Cervical Discectomy and Fusion (ACDF), (ii) Posterior Spinal Fusion, or (iii) Laminectomy, Laminotomy, or Discectomy
- At least 8h of valid pain scores recorded postoperatively
Who cannot join
- Emergency Surgery
- Pregnancy
- Sensitivity to methocarbamol (allergy)
- End-stage renal disease (ESRD)
- Myasthenia gravis
- Missing a valid electronic anesthesia record
Trial locations and contacts
1 site in 1 country.
United States1 site
Memorial Hermann Health System
Houston, Texas, 77007-1708
About this study
The goal of this target trial emulation is to evaluate the impact of intravenous (IV) methocarbamol on postoperative pain and opioid use in adults undergoing elective spine surgery. The main questions it aims to answer are:
- Does IV methocarbamol reduce pain in the 6 hours following surgery?
- Does IV methocarbamol decrease the need for opioid pain medications in the same period?
Participants who receive IV methocarbamol as part of their routine postoperative care will have their pain scores and opioid consumption tracked for 6 hours after treatment. Pain levels will be measured using standard assessments, and opioid use will be quantified in oral morphine equivalents.
Read the detailed description
The IMAPSS study is a target trial emulation evaluating the effect of intravenous (IV) methocarbamol on postoperative pain management and opioid consumption in adult patients undergoing elective spine surgery. The study employs a target trial emulation design to simulate the conditions of a randomized controlled trial using observational data extracted from electronic medical records. The main focus is to determine if administering IV methocarbamol within two hours after surgery reduces postoperative pain scores and opioid use.
Patients will be tracked from the point of their first recorded pain score in the Post-Anesthesia Care Unit (PACU) after surgery to assess for treatment assignment eligibility. Data will be collected at 15-minute intervals, which corresponds to the standard assessment frequency in Phase I PACU care, for up to 12 hours postoperatively for each patient. The primary analysis will use time-varying propensity score matching (TV-PSM) to control for baseline and time-varying confounders. Pain levels will be measured using a time-weighted average (TWA) of pain scores, and opioid consumption will be quantified in oral morphine equivalents (OME).
The primary analysis will utilize TV-PSM, with propensity scores estimated through a Cox proportional hazards model. Matching will create balanced treatment groups at each 15-minute interval. Generalized estimating equations (GEE) will then estimate the effect of IV methocarbamol on the primary outcome (TWA pain) and secondary outcome (cumulative OME) over a 6-hour postoperative period. As a sensitivity analysis, a marginal structural model (MSM) using inverse probability weighting (IPW) will assess the robustness of the findings to the time-varying confounder adjustment.
This study's findings will aim to inform evidence-based recommendations for postoperative pain management and opioid-sparing strategies, potentially providing safer alternatives to conventional opioid-based regimens.
- Conditions
- Acute Post Operative Pain, Postsurgical Pain Management, Spine Surgery, Acute Pain, Postoperative, Multimodal Analgesia
- Being tested
- Intravenous Methocarbamol
- Keywords
- methocarbamol, postoperative pain, Robaxin, spine surgery, acute postsurgical pain, postsurgical pain, target trial emulation, postoperative analgesia, postoperative pain management, multimodal pain management
- Medical subject headings
- Pain, Postoperative
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Intravenous MethocarbamolDrug
Also called Robaxin
At least 500 mg of intravenous methocarbamol administered within 2 hours after the end of elective spine surgery for acute postoperative pain management
| Study group | Role | What they receive |
|---|---|---|
| IV methocarbamol | Patients who received intravenous methocarbamol Receives: Drug: Intravenous Methocarbamol | |
| Usual Care | Patients who received usual postoperative pain management after surgery without any intravenous methocarbamol administration |
What is being measured
The primary outcome is the main question the study is designed to answer.
Time-Weighted Average Pain Score
The primary outcome of this study is the Time-Weighted Average (TWA) pain score measured over the 6-hour period following treatment assignment. Pain scores are collected using a standardized numerical pain rating scale, ranging from 0 (no pain) to 10 (worst possible pain). These scores are assessed in 15-minute intervals, the standard frequency for Phase I PACU assessments, throughout the 6-hour follow-up period. The TWA pain score is calculated by averaging these pain ratings, giving greater weight to scores recorded more frequently or for longer periods. This method provides a comprehensive summary of the patient's pain experience over the observed time frame, accounting for fluctuations in pain intensity during recovery. A lower TWA score indicates better pain control and a potentially greater effect of the intervention.
Measured: 6 hours after treatment assignment
Secondary outcomes (1)
Cumulative Opioid Use
The secondary outcome of this study is the cumulative opioid use measured in Oral Morphine Equivalents (OME) over the 6-hour period following treatment assignment. Opioid doses administered during this timeframe are converted into OME to standardize and compare the total amount of opioids used, accounting for the specific medication, dose, and route of administration. Data on opioid administration are assessed in 15-minute intervals, aligned with standard PACU assessment practices. The cumulative OME reflects the total opioid exposure a patient received, providing a quantitative measure of opioid consumption and its potential reduction with the intervention. Lower cumulative OME values suggest more effective pain management with fewer opioids, indicating the potential benefits of non-opioid alternatives.
Measured: 6 hours after treatment assignment
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted26 Oct 2024
- Study start1 Jan 2020
- Primary completion31 Dec 2023
- Study completion30 Jun 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (1)Papers the sponsor has linked to this study.
- Other trials for Acute Post Operative PainStudies of the same condition, open and under way.
- More trials run by The University of Texas Health Science Center, HoustonThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Cohort
- Time perspective
- Retrospective
- Enrolment
- 1,270 participants (actual)
Sponsor and investigators
- Sponsor type
- University, hospital or other
- Collaborators
- National Institutes of Health (NIH), National Institute of General Medical Sciences (NIGMS)
- Responsible party
- Principal investigator, Paul Potnuru, The University of Texas Health Science Center, Houston
- Investigators
- Paul Potnuru, MD, Principal investigator, The University of Texas Health Science Center, Houston
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06659965
- Sponsor's protocol ID
- HSC-MS-24-1095
- Other IDs
- 5T32GM135118-03
- Acronym
- IMAPSS
- Status last verified
- Nov 2025
- First submitted
- 24 Oct 2024
- Last updated
- 14 Nov 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes: Individual participant data (IPD) used in the publication of the results will be shared with interested researchers upon request when the required documentation is completed, and a review by the study team is completed and approved.
Publications
Potnuru P, Baranov A, Khudirat M, Turan A. Intravenous methocarbamol for acute pain after spine surgery: a target trial emulation. Reg Anesth Pain Med. 2026 Aug 5;51(8):940-946. doi: 10.1136/rapm-2025-107010.
PubMed 40921494
Study at a glance
From the registry record, last updated by the sponsor on 14 Nov 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Intravenous Methocarbamol for Acute Pain After Spine Surgery
- ClinicalTrials.gov ID
- NCT06659965
- Acronym / sponsor ID
- IMAPSS / HSC-MS-24-1095
- Conditions
- Acute Post Operative Pain, Postsurgical Pain Management, Spine Surgery, Acute Pain, Postoperative, Multimodal Analgesia
- Keywords
- methocarbamol, postoperative pain, Robaxin, spine surgery, acute postsurgical pain, postsurgical pain, target trial emulation, postoperative analgesia
- Study type
- Observational
- Recruitment status
- Completed
- Enrolment
- 1,270 participants (actual)
- Lead sponsor
- The University of Texas Health Science Center, HoustonUniversity, hospital or other
- Collaborators
- National Institutes of Health (NIH), National Institute of General Medical Sciences (NIGMS)
- Study start
- 1 Jan 2020 (actual)
- Primary completion
- 31 Dec 2023 (actual)
- Study completion
- 30 Jun 2025 (actual)
- First posted
- 26 Oct 2024 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The goal of this target trial emulation is to evaluate the impact of intravenous (IV) methocarbamol on postoperative pain and opioid use in adults undergoing elective spine surgery. The main questions it aims to answer are:
- Does IV methocarbamol reduce pain in the 6 hours following surgery?
- Does IV methocarbamol decrease the need for opioid pain medications in the same period?
Participants who receive IV methocarbamol as part of their routine postoperative care will have their pain scores and opioid consumption tracked for 6 hours after treatment. Pain levels will be measured using standard assessments, and opioid use will be quantified in oral morphine equivalents.
Detailed description
The IMAPSS study is a target trial emulation evaluating the effect of intravenous (IV) methocarbamol on postoperative pain management and opioid consumption in adult patients undergoing elective spine surgery. The study employs a target trial emulation design to simulate the conditions of a randomized controlled trial using observational data extracted from electronic medical records. The main focus is to determine if administering IV methocarbamol within two hours after surgery reduces postoperative pain scores and opioid use.
Patients will be tracked from the point of their first recorded pain score in the Post-Anesthesia Care Unit (PACU) after surgery to assess for treatment assignment eligibility. Data will be collected at 15-minute intervals, which corresponds to the standard assessment frequency in Phase I PACU care, for up to 12 hours postoperatively for each patient. The primary analysis will use time-varying propensity score matching (TV-PSM) to control for baseline and time-varying confounders. Pain levels will be measured using a time-weighted average (TWA) of pain scores, and opioid consumption will be quantified in oral morphine equivalents (OME).
The primary analysis will utilize TV-PSM, with propensity scores estimated through a Cox proportional hazards model. Matching will create balanced treatment groups at each 15-minute interval. Generalized estimating equations (GEE) will then estimate the effect of IV methocarbamol on the primary outcome (TWA pain) and secondary outcome (cumulative OME) over a 6-hour postoperative period. As a sensitivity analysis, a marginal structural model (MSM) using inverse probability weighting (IPW) will assess the robustness of the findings to the time-varying confounder adjustment.
This study's findings will aim to inform evidence-based recommendations for postoperative pain management and opioid-sparing strategies, potentially providing safer alternatives to conventional opioid-based regimens.
Study design
- Observational model
- Cohort
- Time perspective
- Retrospective
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| IV methocarbamol | – | Drug: Intravenous MethocarbamolPatients who received intravenous methocarbamol |
| Usual Care | – | –Patients who received usual postoperative pain management after surgery without any intravenous methocarbamol administration |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
- Study population
- The study population consists of adult patients undergoing elective spine surgeries at multiple hospitals within a large health system in Houston, TX. This includes individuals receiving surgical interventions for conditions such as degenerative disc disease, spinal stenosis, or other spinal pathologies that require procedures like ACDF, posterior spinal fusion, or laminectomy. Participants will be selected from those who receive perioperative care across various hospital settings within the health system, including postoperative management in the Post-Anesthesia Care Unit (PACU).
Key inclusion criteria (3 listed)
- 18 years of age or older
- Undergoing one of the following three elective spine surgeries: (i) Anterior Cervical Discectomy and Fusion (ACDF), (ii) Posterior Spinal Fusion, or (iii) Laminectomy, Laminotomy, or Discectomy
- At least 8h of valid pain scores recorded postoperatively
Key exclusion criteria (6 listed)
- Emergency Surgery
- Pregnancy
- Sensitivity to methocarbamol (allergy)
- End-stage renal disease (ESRD)
- Myasthenia gravis
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Intravenous MethocarbamolAlso: RobaxinAt least 500 mg of intravenous methocarbamol administered within 2 hours after the end of elective spine surgery for acute postoperative pain management | Drug | IV methocarbamol |
Primary outcome
Time-Weighted Average Pain Score
Time frame: 6 hours after treatment assignment
The primary outcome of this study is the Time-Weighted Average (TWA) pain score measured over the 6-hour period following treatment assignment. Pain scores are collected using a standardized numerical pain rating scale, ranging from 0 (no pain) to 10 (worst possible pain). These scores are assessed in 15-minute intervals, the standard frequency for Phase I PACU assessments, throughout the 6-hour follow-up period. The TWA pain score is calculated by averaging these pain ratings, giving greater weight to scores recorded more frequently or for longer periods. This method provides a comprehensive summary of the patient's pain experience over the observed time frame, accounting for fluctuations in pain intensity during recovery. A lower TWA score indicates better pain control and a potentially greater effect of the intervention.
1 secondary outcome
Cumulative Opioid Use
Time frame: 6 hours after treatment assignment
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 14 Nov 2025.
- Background: PubMed 40921494Potnuru P, Baranov A, Khudirat M, Turan A. Intravenous methocarbamol for acute pain after spine surgery: a target trial emulation. Reg Anesth Pain Med. 2026 Aug 5;51(8):940-946. doi: 10.1136/rapm-2025-107010.
- Individual participant dataSharing planned: Yes. Individual participant data (IPD) used in the publication of the results will be shared with interested researchers upon request when the required documentation is completed, and a review by the study team is completed and approved.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Paul Potnuru, MD principal investigator
The University of Texas Health Science Center, Houston
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Acute Post Operative Pain and Postsurgical Pain Management, run by The University of Texas Health Science Center, Houston at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 3 inclusion and 6 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 14 Nov 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Time-Weighted Average Pain Score (time frame: 6 hours after treatment assignment). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT06659965, which also lists 1 linked publication.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 14 Nov 2025.