Dexmedetomidine in the Treatment of Symptoms Of Acute Opioid Withdrawal: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Dexmedetomidine in the Treatment of Symptoms Of Acute Opioid Withdrawal (NCT04470050), a randomized phase 1, phase 2 study. The primary outcome is Peak SOWS Scores at Baseline and Over Time.

2. Clinical Question

The study was designed to assess safety, pharmacokinetics, and early signs of efficacy following discontinuation of morphine maintenance. Its clinical question is therefore framed around symptom scores during a defined inpatient treatment sequence, rather than a long-term outcome. The primary score is patient-reported and measures withdrawal symptoms; secondary outcomes include other symptom measures, time to dropout, dropout counts, and an ACES score. The posted record does not include the result estimates needed to describe whether scores differed between treatment groups, how large any differences were, or how precisely they were estimated. The clinical question can be identified from the protocol summary, but the numerical answer to it is not reported in the registry record.

3. Trial Design

This was a Phase 1b/2 randomized, double-blind, placebo-controlled, ascending-dose study. The registry record describes the masking as quadruple and the intervention model as sequential. It lists BioXcel Therapeutics Inc as the sponsor and the status as completed. Enrollment is recorded as 225. The study start date is 2020-06-09, and primary completion is recorded as 2021-02-18.

The study had two stated phases. The morphine maintenance phase, identified as Phase 1b, included Days 1-5. After morphine maintenance was discontinued, the randomized BXCL501/placebo phase, identified as Phase 2, included Days 6-12. Six escalating dexmedetomidine dose cohorts are listed, with placebo as the comparator. Following the randomized phase, the record describes two sequential days, Days 13 and 14, using BXCL501-placebo sublingual films and morphine-placebo capsules for participants who remained in the study.

The description identifies the treatment sequence and dose levels, but not the detailed randomization procedure, allocation ratio, or how participants were distributed among the sequential cohorts. Those details are not reported in the registry record. Nor does the record specify the number assigned to each dose group in the efficacy analysis. The sample sizes listed with the adverse-event results are safety counts and should not be treated as group sizes for the primary outcome.

Peak SOWS score at baseline and over time was the primary outcome. The registry record also lists seven outcome measures, including the primary measure and several secondary measures. It reports zero analyses, so no numerical inferential results, effect estimates, or confidence intervals are available in the registry record for interpretation. The overall enrollment and completed status describe trial conduct; they do not establish that all planned measurements were reported or that every participant contributed data at every time point.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Only the first 6 of 7 groups are shown.

Opioid Maintenance Phase

Double-blind Treatment Phase

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Full Analysis Set (FAS)

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

Only the first 6 of 8 groups are shown.

6. Primary Endpoint

The registry lists the primary outcome as Peak SOWS Scores at Baseline and Over Time, measured over Baseline (pre-dose day 6) and at days 6, 7, 8, 9, 10, 11, 12, 13, and 14 post-dose.

The primary endpoint was peak Short Opiate Withdrawal Scale (SOWS)-Gossop score at baseline and over time. The record specifies baseline as pre-dose on day 6, with post-dose measurements on days 6 through 14. SOWS-Gossop is described as a validated, 10-item patient-reported scale for withdrawal symptoms in people dependent on opioids. Its items cover feeling sick, stomach cramps, muscle spasms or twitching, feeling cold, heart pounding, muscular tension, aches and pains, yawning, runny eyes, and insomnia or problems sleeping.

The total score ranges from 0 to 30, with higher scores indicating greater withdrawal symptom severity. A peak score focuses on the highest recorded score within the relevant measurement period, whereas a mean score describes an average; these summaries answer different questions. The primary measure is therefore intended to capture the reported intensity of withdrawal symptoms, while the recorded time points allow the symptom profile to be followed through the study schedule.

As a general statistical consideration, repeated symptom measurements can describe both the level and course of a measure. Interpretation depends on which time point or summary is compared, how missing measurements are handled, and whether between-group estimates include uncertainty. The registry record identifies the endpoint and its measurement schedule but does not report the numerical peak scores, standard deviations, between-group contrasts, or confidence intervals. The endpoint's intended meaning is clear, but its observed pattern and precision cannot be assessed from the posted results.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The statistical methods that can be interpreted from the registry record are limited. It identifies the primary measure as a continuous score, reports mean as the parameter and standard deviation as the dispersion, and names the Full Analysis Set as the primary outcome population. It does not report numerical outcome analyses. Statistical explanations below are general and do not imply that a particular method was used in this trial.

What does a mean and standard deviation describe?

In general, a mean summarizes the average score among the observations included in an analysis. A standard deviation describes how spread out individual scores are around that average. Together they convey a group-level location and variability, but they do not show every participant's score or the full shape of the score distribution. The registry record names these summaries for the primary outcome but does not report the corresponding numbers.

A group mean on its own is not a treatment comparison. To compare randomized groups, an analysis typically presents a contrast, such as a difference in means, with an estimate of uncertainty. A confidence interval expresses a range of values compatible with the data and the analysis assumptions; narrower intervals generally indicate greater precision than wider intervals. A p-value, when reported, addresses compatibility with a specified null hypothesis under a statistical model. Neither confidence intervals nor p-values are reported for the primary endpoint in the registry record, so statistical significance and precision cannot be assessed.

Why do repeated measurements need careful interpretation?

The primary outcome schedule includes baseline and repeated post-dose time points. Repeated scores from the same participant are related, rather than independent observations. General methods for repeated measures account for this within-participant relationship and can estimate time patterns or between-group differences while using observations across visits. The choice of method affects the estimand, assumptions, and interpretation. The registry record does not report the model, covariance assumptions, contrast definitions, or whether the primary comparison was made at a particular time point or across the sequence.

The endpoint is described as peak SOWS score at baseline and over time. Peak summaries focus on the maximum recorded score over a defined period, while an average over visits reflects a different aspect of symptom experience. When measurements are missed, the observed maximum may not represent the unobserved peak. General analyses of repeated outcomes therefore need to state how the time window and missing measurements are handled. Those details are not reported in the registry record.

What is the role of the Full Analysis Set?

The Full Analysis Set is named as the primary endpoint population. In general, analysis populations define which randomized participants contribute to an estimate, and the definition can affect interpretation. The name alone does not establish which participants were included, whether assignment was retained for analysis, or how deviations and missing observations were treated. The operational definition of the Full Analysis Set is not reported in the registry record.

How should dose-ranging results be analyzed?

With several active dose levels and a placebo comparator, possible analyses include separate contrasts for each dose, an ordered trend, or a model describing dose response. These approaches answer distinct questions and may rely on different assumptions. The sequential model designation and escalating-dose description do not reveal which approach was used. The registry record reports no analyses and does not describe a dose-response method or the prespecified primary contrast.

Multiple dose comparisons and multiple outcomes raise a general multiplicity issue. If many hypotheses are tested, the chance of at least one apparently unusual result can increase unless the analysis plan controls or otherwise addresses multiplicity. Adjustment methods, a testing hierarchy, and the distinction between confirmatory and exploratory outcomes are not reported in the registry record. No claim about multiplicity control can therefore be made.

What does the sample-size illustration represent?

The record describes planning illustrations based on the observed effect, using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the effect to detect is a stated fraction of the observed effect. It distinguishes participants per arm for continuous outcomes from total events for time-to-event outcomes. These are planning illustrations, not observed power and not evidence that the trial was designed with those assumptions. The registry record does not report the trial's own sample-size justification. Because primary numerical results and the observed effect are not reported, no numerical planning result can be interpreted from the record.

Over-dispersion is a general issue for count outcomes when variability exceeds what a simple model assumes; it can make standard errors too small if ignored. That concept does not directly provide an analysis of the continuous SOWS score, and the record does not report a count-outcome model. More broadly, statistical methods should be matched to the endpoint and design, and their assumptions should be reported. Here, the registry record names the endpoint summaries and population but leaves the inferential methods and numerical results unavailable.

10. Multiplicity, Missing Data and Analysis Populations

The record lists seven outcome measures, including the primary peak SOWS outcome and secondary measures. Repeated measurement times and several dose comparisons can create multiple opportunities for testing. As a general statistical principle, multiplicity matters because interpreting many separate tests without a stated strategy can make isolated findings difficult to distinguish from chance variation. A prespecified hierarchy, adjustment method, or clear separation of confirmatory and exploratory analyses can help readers understand that issue. Such a strategy is not reported in the registry record.

The record reports zero analyses. It therefore does not provide evidence about how the listed outcomes were analyzed, which contrasts were prioritized, or whether any adjustment for multiple comparisons was used. The number of listed outcomes alone does not establish how many tests were performed. No multiplicity-adjusted conclusion can be reconstructed from the record.

Missing-data handling is also not reported in the registry record. This matters because the primary outcome was measured repeatedly, and the study description includes dropout outcomes. In general, participants may have incomplete scores because they leave the study or miss a measurement. Analyses can differ in the assumptions they make about the reasons for missingness and the values that would have been observed. A complete-case analysis, a model using available repeated observations, and imputation are examples of approaches with different assumptions; the record does not say whether any of these was used.

The Full Analysis Set is identified as the primary population, but its membership criteria are not reported. The record does not explain how participants who discontinued treatment, withdrew, or lacked a score were handled in the primary analysis. Enrollment of 225 should not be read as the number contributing to every outcome or time point. Without population definitions, missing-data methods, and analyses, the robustness of any efficacy result cannot be assessed; moreover, numerical efficacy results are not reported.

11. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 5% reporting threshold.

Most frequent non-serious adverse event terms

The registry lists safety counts for six dexmedetomidine dose groups and pooled placebo. In every listed group, the serious adverse event count is 0, and deaths are recorded as 0. The number at risk for serious adverse events and for other adverse events is listed for each group. For other adverse events, the counts of affected participants are 1 at 30 micrograms, 5 at 60 micrograms, 2 at 90 micrograms, 4 at 120 micrograms, 8 at 180 micrograms, 9 at 240 micrograms, and 5 with pooled placebo.

These are counts, not rates or comparative estimates. The registry record does not report percentages or an inferential analysis for adverse events, and those should not be inferred from the counts. The groups also have different numbers at risk, so raw counts alone do not establish which group had greater risk. The record's top serious adverse event terms list is empty; this does not provide descriptions of the other adverse events.

In general, safety results are interpreted in light of event definitions, observation periods, exposure, severity, and the completeness of reporting. The registry record does not report those details beyond the listed counts and the study schedule. Zero listed serious adverse events and zero deaths describe the recorded counts; they do not prove that no unrecorded events occurred or establish equivalence between treatments.

12. What the Result Does, and Does Not, Mean

The registry record establishes that the study was randomized, double-blind, placebo-controlled, and designed to assess escalating doses of BXCL501 after discontinuation of morphine maintenance. It identifies a patient-reported withdrawal score as the primary endpoint and gives its measurement schedule and scale interpretation. It also records safety counts for each dose group and pooled placebo. These registry entries describe the question and the reported study structure, not an efficacy result.

The primary numerical results are not reported in the registry record. Consequently, the available information does not show whether peak SOWS scores changed differently across groups, the size or direction of any group contrast, or its statistical precision. It also does not establish a dose-response pattern. A completed trial can have results that are not present in a registry entry; completion status alone cannot fill that information gap.

The safety counts offer a limited descriptive account. No serious adverse events or deaths are listed in any of the reported groups, and counts of participants with other adverse events are given. Without event descriptions, comparative analyses, and fuller context, these counts cannot support a broad conclusion about relative safety.

In general, interpreting a randomized trial requires estimates linked to the planned question, along with uncertainty intervals, analysis-population definitions, and an account of missing data and multiplicity. Those details are not reported for the primary outcome. The defensible reading is therefore narrow: the record describes the trial design and endpoint, and it reports certain safety counts, but it does not provide the numerical evidence needed to characterize the primary efficacy result. This is not a finding of no effect or of equal outcomes. It is a limitation of what the registry record reports.

13. Why This Trial Matters Statistically

This trial is statistically notable as a dose-ranging study with a repeated patient-reported endpoint. Its escalating-dose structure creates a question about how response varies across dose levels, while the repeated SOWS measurements make the time course relevant. These features require a clear definition of the comparison of interest: a single dose-versus-placebo contrast, a trend across doses, or change over time are not interchangeable questions.

The record is also a useful example of the distinction between a study description and an interpretable result. It contains the trial phase, design characteristics, outcome definition, measurement schedule, and enrollment, but reports zero analyses and no numerical primary outcome findings. Without estimates and measures of uncertainty, readers cannot judge the size or precision of the primary comparison, even when the endpoint is described in detail.

The listed secondary outcomes add further analytical dimensions, including symptom measures, dropout, and an ACES score. A comprehensive statistical account would explain how these outcomes relate to the primary question, how multiplicity was addressed, and which analysis populations and missing-data assumptions were used. Those details are not reported in the registry record. Their absence prevents a reader from distinguishing planned analyses from exploratory ones or from assessing the reliability of any individual finding.

The safety listing supplies some group-level counts, but it does not replace efficacy estimates or a full account of adverse events. The main statistical lesson is that design labels and outcome definitions establish what a trial set out to study, while estimates, uncertainty, and transparent methods are needed to understand what its data show. In this record, the former are available more fully than the latter.

14. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The most important limitation for interpreting this trial from the registry record is that numerical results for the primary outcome are not reported. Means, standard deviations, treatment contrasts, confidence intervals, and p-values are unavailable. The registry record reports zero analyses, so it is not possible to assess the observed SOWS pattern, the magnitude of any dose-placebo difference, or the precision of an estimate.

Although the primary population is named as the Full Analysis Set, its definition and membership are not reported. The record also does not explain how missing repeated scores, discontinuations, or other deviations were handled. This is particularly relevant because dropout is itself listed as a secondary outcome and the primary endpoint is measured across multiple days.

The registry identifies randomization, quadruple masking, and a sequential model, but does not report the allocation procedure, distribution of participants across dose cohorts, or the detailed analysis plan. It also does not report a multiplicity strategy for the several outcome measures and potential dose comparisons. The registry record does not provide the trial's own sample-size justification; the described planning illustrations are not a substitute for that justification.

The safety information is limited to counts at risk, counts with other adverse events, serious adverse event counts, and deaths. The record does not provide details of other adverse events or comparative safety analyses. Together, these omissions mean the record supports a description of the trial design and selected safety counts, but not a complete assessment of efficacy, precision, missing-data sensitivity, or comparative safety.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Dexmedetomidine in the Treatment of Symptoms Of Acute Opioid Withdrawal — NCT04470050.
• Registry record last updated 2026-08-11; status last verified 2026-08.
• Results first posted 2023-10-26.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

18. Record Summary

NCT04470050 is a completed Phase 1b/2 randomized, double-blind, placebo-controlled, ascending-dose inpatient study sponsored by BioXcel Therapeutics Inc. Enrollment is recorded as 225. The study assessed BXCL501, a dexmedetomidine sublingual film, after discontinuation of morphine maintenance, across six dose cohorts from 30 to 240 micrograms, with placebo as comparator.

The primary outcome was peak SOWS-Gossop score at baseline and over time, using baseline pre-dose on day 6 and post-dose measurements on days 6 through 14. The registry record describes the score as ranging from 0 to 30, with higher scores indicating greater withdrawal symptom severity. It identifies the Full Analysis Set as the primary population and lists seven outcome measures.

Numerical primary-outcome results and analyses are not reported in the registry record. Safety listings report zero serious adverse events and zero deaths in each group, alongside counts of participants with other adverse events. Analysis methods, missing-data handling, and multiplicity procedures are not reported.