This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Study to Evaluate the Pharmacokinetics of Mucinex 600 mg Extended-release Bi-layer Tablet in Healthy Volunteers (NCT03644108), a na phase 1 study. The primary outcome is Maximum Observed Plasma Concentration (Cmax) of Guaifenesin.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT03644108 |
| Phase | Phase 1 |
| Condition | Healthy Subjects |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 30 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Reckitt Benckiser Inc. |
| Results posted | Yes |
2. Clinical Question
Population
The study enrolled healthy subjects. The registry record states that all 30 subjects were included in the guaifenesin concentration tables and in the calculation of guaifenesin pharmacokinetic parameters. The record describes the population as normal healthy subjects; it does not report further eligibility details or demographic characteristics.
Intervention
Participants received a single dose of Mucinex® 600 mg Extended-Release Bi-Layer tablet, identified in the record as Mucinex® ER 600 mg. The dose was taken with 240 mL of water after an overnight fast. The study was open-label, so masking was not used.
Comparator
There was no comparator group. This was a single-group study, and allocation was recorded as not applicable. The registry record therefore does not provide a randomized or controlled comparison of the study drug against another treatment, a different dose, or placebo.
Primary question
The primary endpoint was the maximum observed plasma concentration, or Cmax, of guaifenesin, expressed in ng/mL and summarized using a geometric mean with geometric coefficient of variation. The clinical-pharmacology question was how the concentration of guaifenesin in plasma reached its observed maximum after the single dose. The numerical Cmax result is not reported in the registry record, so its magnitude and precision cannot be described from this record.
3. Trial Design
This was a Phase I, open-label, single-dose, single-period, single-group study in healthy subjects. The registry record lists Mucinex® ER 600 mg as the intervention and describes a single dose of the 600 mg extended-release bi-layer tablet taken with 240 mL of water after an overnight fast. There was no control arm, and allocation was not applicable. Because the study was not randomized and had no comparator, it cannot provide a like-for-like treatment contrast.
The registry lists enrollment of 30 and status as completed. The study began on 2009-06-04, and primary completion was recorded on 2009-06-15. The record states that all 30 subjects were included in the guaifenesin concentration tables and the calculation of guaifenesin pharmacokinetic parameters. It does not give further details about participant flow, exclusions, or withdrawals.
The primary outcome was maximum observed plasma concentration of guaifenesin. Its stated timeframe included pre-dose and multiple post-dose measurement times through 24 hours on Day 1 and 2. The record also lists the number of subjects with treatment-emergent adverse events as a secondary outcome. It lists 8 outcome measures and 0 analyses, but does not describe the statistical procedures used to analyze those outcomes.
The registry record does not report a sample-size justification, a prespecified statistical analysis plan, or details of any interim analyses. The sample-size assumptions associated with planning illustrations do not describe the study’s own design or justify its enrollment. This study is best understood as a descriptive pharmacokinetic and safety assessment in a single group, rather than as a comparative trial.
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.
Before assignment: A total of 30 subjects were screened for the study; All 30 subjects were included single-period.
Overall Study
| Stage | Mucinex® 600 mg ER |
|---|---|
| STARTED | 30 |
| COMPLETED | 30 |
| NOT COMPLETED | 0 |
Analysis population for the primary outcome, as defined in the registry: Data Sets Analyzed as all 30 subjects were included in the guaifenesin concentration tables and the calculation of guaifenesin Pharmacokinetic (PK) parameters.
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.
| Characteristic | Unit | Mucinex® 600 mg ER |
|---|---|---|
| Participants analysed | 30 | |
| Age, Continuous | years | 26.3 (SD 6.97) |
| Sex: Female, Male: Female | Participants | 15 |
| Sex: Female, Male: Male | Participants | 15 |
| Race: Asian | Participants | 1 |
| Race: Black | Participants | 2 |
| Race: Caucasian | Participants | 27 |
| Weight | lb | 160.4 (SD 23.11) |
| Height | in | 68.41 (SD 3.222) |
| Body Mass Index | kg/m^2 | 23.976 (SD 1.8368) |
6. Primary Endpoint
The registry lists the primary outcome as Maximum Observed Plasma Concentration (Cmax) of Guaifenesin, measured over 0 (Pre-dose), 0.5, 0.75, 1, 1.5, 2, 3, 4, 4.5, 4.75, 5, 5.5, 6, 7, 8, 8.5, 8.75, 9, 9.5, 10, 11, 12, 14, 16 and 24 hours (post-dose) on Day 1 and 2.
| Element | Registry entry |
|---|---|
| Result type | Geometric Mean |
| Measure of spread | Geometric Coefficient of Variation |
| Unit | ng/mL |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint was the maximum observed plasma concentration of guaifenesin, known as Cmax. It represents the highest concentration measured in plasma among the scheduled post-dose observations. The registry gives the unit as ng/mL and identifies the summary as a geometric mean with geometric coefficient of variation. The measurement schedule included a pre-dose observation and multiple post-dose times through 24 hours on Day 1 and 2.
In general, Cmax is used in pharmacokinetic studies to characterize the peak concentration observed after dosing. It describes one aspect of drug exposure; it does not by itself describe the full concentration-time profile, the duration of exposure, a clinical benefit, or a comparison with another treatment. Interpretation depends on the measured concentration data and on the analysis choices used to summarize them.
The registry record does not report the numerical Cmax estimate, its geometric coefficient of variation, a confidence interval, or subject-level measurements. Consequently, the endpoint’s value and precision cannot be assessed from the registry record. The stated measurement schedule and summary type identify what was intended to be characterized, but do not establish the size or variability of the observed peak.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry identifies a pharmacokinetic endpoint, but it does not report the numerical result for maximum observed plasma concentration. Without that estimate and its accompanying variability measure, the magnitude of the observed peak concentration cannot be described. The record also does not report a confidence interval or other interval estimate, so the precision of the primary result cannot be assessed. The presence of a defined endpoint and measurement schedule is not a substitute for the endpoint result.
The study included one group receiving a single dose, with no comparator. Its design can describe observations among the participants who received Mucinex® ER 600 mg, but it cannot establish a treatment difference relative to placebo, another product, or another dose. There is no randomized contrast from which to estimate a comparative effect. The registry record does not provide an analysis comparing any groups.
The study population was healthy subjects, and the record states that all 30 subjects were included in the guaifenesin concentration tables and pharmacokinetic calculations. That stated analysis population helps clarify who contributed to the listed endpoint calculations. The registry does not report participant characteristics or detailed inclusion and exclusion criteria, so the extent to which the findings would apply to other populations cannot be assessed from this record.
The record lists a secondary outcome concerning subjects with treatment-emergent adverse events. Its adverse-event figures list 0 subjects with serious adverse events and 5 deaths in the Mucinex® 600 mg ER group. The record does not explain the deaths or reconcile that count with the serious-adverse-event count. These figures should be reported as recorded, without inferring causes, timing, or relationship to treatment.
Overall, the registry record identifies what the study set out to measure and describes some aspects of its design and safety reporting. It does not provide the primary endpoint’s numerical result, detailed statistical methods, or enough safety context to interpret the reported deaths. No conclusion about comparative effects can be drawn from this single-group record.
9. Statistical Methods Explained
The registry describes the primary endpoint as a geometric mean of maximum observed plasma concentration, accompanied by a geometric coefficient of variation. These labels indicate the type of summary intended for the concentration measurements. They do not, by themselves, disclose the calculation procedure, any data transformations, how values below a measurement limit were handled, or how missing observations were treated. Those details are not reported in the registry record.
What does Cmax summarize?
Cmax is the largest observed plasma concentration among the measurements collected after dosing. In general, the observed maximum depends on the timing and frequency of sample collection as well as the concentration profile. A scheduled measurement can identify an observed peak at a sampled time; it does not necessarily identify the precise time or value of a peak between scheduled measurements. The registry lists pre-dose and multiple post-dose observations through 24 hours on Day 1 and 2. It does not report the individual concentration-time data or the observed Cmax value.
Why use a geometric mean?
In general, a geometric mean is a way to summarize positive measurements on a multiplicative scale. It can be useful for pharmacokinetic measurements when values are asymmetric or vary proportionally, rather than by a similar absolute amount. The registry identifies the geometric mean as the summary for this endpoint, but does not give a rationale for choosing it or report whether any transformation or particular estimation procedure was used. The actual geometric mean is not reported in the registry record.
What does geometric coefficient of variation describe?
In general, a coefficient of variation expresses variability relative to a mean; a geometric coefficient of variation is associated with summaries on a multiplicative scale. It describes dispersion, not the uncertainty in the estimated mean. A confidence interval would address uncertainty in an estimate, whereas a variability measure describes how observations are spread. The registry names the geometric coefficient of variation as the dispersion measure but does not report its value. It also does not report a confidence interval for the primary endpoint.
What can a single-group design estimate?
A single-group study can describe the observed response after the intervention within that group. It does not supply a concurrent control group for estimating a treatment contrast. In this study, allocation was not applicable and masking was not used. The record therefore does not support a randomized comparison, and no between-group effect can be inferred. The endpoint is descriptive of the study group and the stated dosing conditions.
What does the analysis population tell the reader?
The registry states that all 30 subjects were included in the guaifenesin concentration tables and calculation of pharmacokinetic parameters. This describes the population included in those analyses, but does not establish that every scheduled sample was available for every subject. The record does not describe missing measurements, participant withdrawals, protocol deviations, or analysis rules for incomplete concentration profiles. It also does not give a separate safety analysis population.
What statistical analysis details are absent?
The registry lists 8 outcome measures and 0 analyses. It does not report a statistical analysis plan, a model, a hypothesis test, an interval-estimation procedure, or any adjustment for multiple testing. It does not state whether analyses were prespecified or describe how potential outliers were handled. The absence of those details prevents a fuller assessment of how the primary summary was obtained and how uncertainty was evaluated.
In general, confidence intervals are useful because they display a range of values compatible with an estimate under a specified method and assumptions. They communicate precision differently from a dispersion statistic. No confidence interval for Cmax is reported in this record. No p-value or comparative test is reported either; in any event, a single-group design does not provide a randomized treatment contrast.
The registry’s planning assumptions describe an illustration based on an observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. Those assumptions do not represent the design of this single-group pharmacokinetic study, and they do not establish that the study was planned or analyzed using those methods. No sample-size justification for this trial is reported in the registry record. Planning illustrations are not observed power and do not replace an estimate with an uncertainty interval.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists 8 outcome measures and identifies maximum observed plasma concentration of guaifenesin as the primary endpoint. It also lists the number of subjects with treatment-emergent adverse events as a secondary outcome. The registry record does not describe a prespecified strategy for handling multiple outcomes or multiple statistical tests. It does not report whether any multiplicity adjustment was planned or used. Because no analyses are listed, there are no reported test results from which to assess such an adjustment.
The record states that all 30 subjects were included in the concentration tables and pharmacokinetic parameter calculations. It does not report whether measurements were missing at particular scheduled times, how incomplete concentration profiles were handled, or whether any subjects were excluded from specific analyses. The statement about inclusion does not establish that all observations were complete.
The registry does not report a detailed analysis-population definition for the adverse-event outcome, nor does it describe the handling of missing safety information. It also does not provide participant flow or reasons for any missing data. These gaps limit assessment of the completeness and consistency of the outcome analyses.
Details of a statistical analysis plan, interim analyses, and a sample-size justification are not reported in the registry record. Their absence should not be filled by assumptions about what was customary or what may have occurred. The available record identifies the primary and secondary outcomes but does not provide the methods needed to evaluate multiplicity or missing-data handling in detail.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Mucinex® 600 mg ER | 0 | 30 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Mucinex® 600 mg ER | 5 of 30 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Mucinex® 600 mg ER | 5 of 30 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Mucinex® 600 mg ER |
|---|---|---|
| Headache | Nervous system disorders | 4 of 30 |
| Nasal congestion | Respiratory, thoracic and mediastinal disorders | 1 of 30 |
For the Mucinex® 600 mg ER group, the registry record lists 0 subjects with serious adverse events among 30 at risk. It lists 5 subjects with other adverse events among 30 at risk, and it reports 5 deaths. These are the recorded figures and should not be combined or reinterpreted beyond the information in the record.
The death count is not explained: the registry record gives no cause, timing, relationship to treatment, or further narrative. It also does not reconcile the reported deaths with the figure of 0 subjects with serious adverse events. The figures therefore have an unresolved inconsistency on their face. The record does not clarify whether the counts reflect different definitions, reporting fields, or an error.
The listed secondary outcome concerns treatment-emergent adverse events, but the registry does not provide event terms or further details for the reported counts. The serious-event terms list is empty. These data do not establish causation, and the record does not provide enough context to interpret the deaths. The appropriate reading is to report the registry figures as recorded while recognizing that their relationship and meaning are not explained.
12. What the Result Does, and Does Not, Mean
The registry record describes a Phase I study in healthy subjects that gave a single dose of Mucinex® ER 600 mg and identified guaifenesin Cmax as its primary pharmacokinetic endpoint. It gives the endpoint’s unit and summary type, along with a sampling schedule. It also states that all 30 subjects were included in the concentration tables and pharmacokinetic calculations.
What the record does not provide is the numerical Cmax result or its geometric coefficient of variation. It also does not report a confidence interval or subject-level concentration data. As a result, readers cannot determine the observed peak concentration or how precisely it was estimated from this record. A stated endpoint is not evidence of a particular result.
The single-group design has no randomized comparator. It therefore does not estimate a treatment difference and cannot establish how the observed pharmacokinetic profile compares with another dose, product, or control. The study’s healthy-subject population also limits what can be inferred about populations not described in the record.
The safety record lists 0 subjects with serious adverse events, 5 with other adverse events, and 5 deaths. It does not explain the deaths or reconcile them with the serious-event count. Without that context, the figures cannot be used to attribute deaths to the intervention or to make a detailed safety interpretation.
In general, pharmacokinetic measures characterize drug concentrations over time; they are not, on their own, evidence of clinical benefit or harm. This record supports describing the study design, endpoint, stated analysis population, and recorded safety figures. It does not support a comparative efficacy conclusion, a precise estimate of Cmax, or an explanation of the safety counts.
13. Why This Trial Matters Statistically
This study is statistically informative in part because it illustrates the difference between an endpoint definition and a reportable result. The registry clearly identifies Cmax as the primary measure, specifies a geometric-mean summary and geometric coefficient of variation, and gives the concentration measurement schedule. Yet the numerical endpoint result is not reported in the registry record. Without the estimate and a measure of uncertainty, readers cannot assess its magnitude or precision.
The design also matters to interpretation. A single-group study can characterize observations after dosing under the stated conditions, but it does not create a controlled treatment comparison. Recognizing that boundary prevents a descriptive pharmacokinetic study from being read as though it estimated a difference between interventions.
The record’s statement that all 30 subjects were included in the pharmacokinetic calculations is useful information about the stated analysis population. At the same time, it does not describe completeness of sampling or the handling of missing measurements. Statistical interpretation depends on both who is included and how observations are processed; the registry does not report those additional details.
The adverse-event figures underscore why clear, internally interpretable reporting matters. The record lists no subjects with serious adverse events and reports 5 deaths, but offers no explanation of the relationship between these entries. Keeping the figures distinct and identifying the missing context is more informative than drawing an unsupported causal conclusion.
Overall, the study’s registry entry allows readers to understand its basic single-dose pharmacokinetic question and some aspects of its design. It also demonstrates the limits of interpreting a trial when numerical outcome results and key analytic details are absent. Those limits are central to a careful statistical reading.
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 consequential limitation of the registry record is that it does not report the numerical result for the primary endpoint. Although it identifies Cmax, its unit, summary type, dispersion measure, and sampling schedule, it provides no estimate or reported value for the geometric coefficient of variation. There is therefore no basis in the record for describing the observed concentration or its precision.
The study had a single group and no comparator. It was open-label, and allocation was not applicable. Thus, it does not provide a randomized contrast. Its findings, even if numerical pharmacokinetic results were available, would describe the study group under the stated dosing conditions rather than estimate a comparative effect.
The registry states that all 30 subjects were included in the pharmacokinetic calculations, but does not report participant characteristics, detailed eligibility criteria, withdrawals, or missing measurements. It does not explain how incomplete concentration profiles or other data issues were handled. The record also does not report the statistical analysis plan, sample-size justification, interim analyses, or multiplicity strategy.
Safety interpretation is limited by the absence of event details and the unexplained reporting of 5 deaths alongside 0 subjects with serious adverse events. Causes, timing, treatment relationship, and the meaning of these entries are not reported in the registry record. These limitations preclude a more detailed interpretation of the safety figures.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Study to Evaluate the Pharmacokinetics of Mucinex 600 mg Extended-release Bi-layer Tablet in Healthy Volunteers — NCT03644108.
- Registry record last updated 2019-02-28; status last verified 2019-02.
- Results first posted 2019-02-28.
- 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.
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18. Record Summary
The registry record describes a completed Phase I, open-label, single-dose, single-period study in healthy subjects. Enrollment was 30. Participants received one dose of Mucinex® ER 600 mg with 240 mL of water after an overnight fast. There was no comparator group.
The primary endpoint was maximum observed plasma concentration of guaifenesin, summarized as a geometric mean with geometric coefficient of variation. Concentrations were scheduled from pre-dose through 24 hours on Day 1 and 2. The record states that all 30 subjects were included in pharmacokinetic calculations, but does not report the numerical primary result.
The registry lists 8 outcome measures and 0 analyses. It reports 0 subjects with serious adverse events, 5 with other adverse events, and 5 deaths, without explaining the deaths or reconciling the serious-event figure. Detailed statistical methods and missing-data procedures are not reported in the registry record.