A Pharmacokinetic Study of TAK-438 in Healthy Adult Chinese Participants: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for A Pharmacokinetic Study of TAK-438 in Healthy Adult Chinese Participants (NCT03085836), a non-randomized phase 1 study. The primary outcome is Cmax: Maximum Observed Plasma Concentration for Free Base of TAK-438 (TAK-438F) and Its Metabolites M-I, M-II, M-III and M-IV-Sul on Day 1.

2. Clinical Question

The study asks how TAK-438 concentrations in plasma change after participants receive single and repeated oral doses. Its primary endpoint is the maximum observed plasma concentration, or Cmax, on Day 1, with separate measurements specified for TAK-438F and the metabolites M-I, M-II, M-III and M-IV-Sul. The record also identifies single- and multiple-dose administration as the study’s broader pharmacokinetic purpose.

The registry record does not report numerical Cmax results, so the size and precision of the observed concentrations cannot be described from the posted record. Nor does this design establish a randomized estimate of differences among regimens. Its stated focus is pharmacokinetic description in the enrolled population, rather than a clinical outcome comparison.

3. Trial Design

This was an open-label, single-center, parallel Phase 1 study with non-randomized allocation and no masking. The registry reports enrollment of 33 participants and a completed status. The study start date was 2017-04-19, and primary completion was 2017-08-17. Takeda is listed as the sponsor.

The three described regimens were TAK-438 10 mg once daily, TAK-438 20 mg once daily, and TAK-438 20 mg twice daily. The once-daily schedules specify dosing on Day 1 and Days 3-9. The twice-daily schedule specifies one dose on Day 1 and twice-daily dosing on Days 3-9. For the 10 mg once-daily arm, participants were required to fast for a minimum of 10 hours before administration. The other arm descriptions ask participants to fast for a minimum of 10 hours, with the twice-daily description specifying fasting before breakfast and administration 0.5 hours after breakfast and dinner.

Because assignment was not randomized, differences between the regimen groups cannot be treated as if they arose from random allocation. The registry explicitly cautions that the arms are not a like-for-like control comparison. The record does not report how participants were assigned to regimens, so the allocation process should not be inferred from the arm descriptions.

The primary endpoint is described for the pharmacokinetic set, not simply for everyone enrolled. That set includes participants meeting the record’s criteria for drug receipt, concentration data, minimum procedures, and protocol deviations. The number meeting those criteria is not reported in the registry record. Detailed protocol rationale, including the justification for the enrollment target, is also not reported in the registry record.

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: Healthy Chinese participants were enrolled in this study to receive treatment in one of the 3 treatment groups: TAK-438 10 milligram (mg) once daily or TAK-438 20 mg once daily or TAK-438-20 mg twice daily.

Overall Study

Analysis population for the primary outcome, as defined in the registry: The PK set included all participants who received the study drug, had sufficient plasma/urine concentration data to calculate at least 1 PK parameter, and completed the minimum protocol specified procedures with no significant protocol deviations.

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.

Population: The pharmacokinetic (PK) set included all participants who received the study drug, had sufficient plasma/urine concentration data to calculate at least 1 PK parameter, and completed the minimum protocol specified procedures with no significant protocol deviations.

6. Primary Endpoint

The registry lists the primary outcome as Cmax: Maximum Observed Plasma Concentration for Free Base of TAK-438 (TAK-438F) and Its Metabolites M-I, M-II, M-III and M-IV-Sul on Day 1, measured over Day 1 pre-dose and at multiple timepoints (up to 48 hours) post-dose.

Cmax is the maximum observed plasma concentration of a substance during the specified sampling period. For this study, the endpoint concerns TAK-438F, the free base of TAK-438, and its metabolites M-I, M-II, M-III and M-IV-Sul on Day 1. The stated timeframe begins with a pre-dose assessment and includes multiple post-dose timepoints up to 48 hours. The registry identifies the endpoint’s summary measure as a mean and its dispersion measure as a standard deviation, with concentration expressed in nanograms per milliliter.

General: Cmax is used in pharmacokinetic studies to describe the highest measured concentration after dosing. It is informative about the concentration profile, but it does not by itself describe the full time course or total exposure. Its value also depends on the timing and coverage of sample collection: the maximum observed at sampled times is not necessarily the exact concentration peak between those times.

The registry record does not report the actual Cmax means or standard deviations. It therefore does not support a numerical account of the endpoint’s magnitude, variability, or differences between regimens. The listed endpoint definition explains what was intended to be summarized, not what the observed concentrations were.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The record identifies a continuous pharmacokinetic endpoint summarized by a mean and standard deviation. It also describes a pharmacokinetic analysis population and a non-randomized parallel design. However, it does not report the numerical endpoint summaries or a detailed statistical analysis plan. The statistical interpretation must therefore distinguish the stated measurement and population from analyses that are not documented.

What does the mean describe?

General: For a continuous measurement such as plasma concentration, the mean is an average across the participants included in the analysis. It gives a central summary in the endpoint’s measurement units, but it does not show whether individual measurements cluster closely around that value or vary substantially. The registry specifies the mean as the endpoint parameter, but the numerical means are not reported in the registry record.

What does the standard deviation add?

General: The standard deviation describes the spread of individual measurements around the mean. It is a measure of observed variability, not a confidence interval and not a measure of uncertainty in the mean itself. A standard deviation can help readers judge whether participants’ concentrations were relatively similar or dispersed, but the record does not give the standard deviations for the primary endpoint. The actual spread therefore cannot be assessed.

What is Cmax, and what can it miss?

General: Cmax is the highest measured concentration for a substance over the specified sampling period. It condenses a concentration-time profile into a single peak-related summary. The sampling schedule matters because measurements taken at discrete timepoints may not capture the exact peak between observations. The record specifies pre-dose and multiple post-dose measurements up to 48 hours for the primary endpoint; it does not report the observed values at those timepoints or the resulting Cmax summaries.

Cmax also answers a narrower question than a measure integrating concentrations across time. It does not alone describe the duration of exposure or the complete shape of a concentration-time curve. The primary endpoint is explicitly a maximum observed concentration, so interpretation should remain focused on that quantity rather than treating it as a complete summary of pharmacokinetics.

Who is included in the primary analysis population?

The pharmacokinetic set is defined as participants who received study drug, had sufficient plasma or urine concentration data to calculate at least one pharmacokinetic parameter, and completed the minimum protocol-specified procedures without significant protocol deviations. This definition indicates that the endpoint analysis was not necessarily intended to include every enrolled participant. The registry does not report how many participants met the criteria, how many were excluded, or the reasons for any exclusions. Those details are not reported in the registry record.

General: Defining an analysis population matters because estimates apply to the participants actually included. If eligibility for analysis depends on having usable measurements or completing procedures, the analyzed group may differ from the enrolled group. Without participant flow and the analysis-set count, readers cannot assess the extent or potential consequences of exclusions for this endpoint.

What does the design imply for comparisons?

The study is described as parallel and non-randomized, with no masking. The three arms received different TAK-438 regimens. The registry warns that the arms are not a like-for-like control comparison. Non-randomized assignment can leave group differences entangled with differences in participant characteristics or other aspects of care. The registry record does not report an adjustment method or a statistical comparison plan. Therefore, the design description alone does not justify interpreting a difference between groups as caused by the dosing regimen.

General: Random allocation is one way to reduce systematic differences between comparison groups, on average. In its absence, measured or unmeasured differences may complicate comparisons. Statistical adjustment can address some measured differences when appropriate data and a specified method are available, but it cannot automatically remove all sources of bias. No adjustment approach is reported in the registry record.

How should uncertainty and significance be read?

General: A confidence interval gives a range of values compatible with an estimate under the analysis assumptions and conveys precision as well as direction and magnitude. A p-value, when used, quantifies how unusual data would be under a specified null model; it does not measure the probability that a hypothesis is true. Neither a confidence interval nor a p-value for the primary endpoint or between-arm comparisons is reported in the registry record. No inferential result should be reconstructed from the design description alone.

The registry lists zero analyses. This does not establish that no statistical work was done; it means the registry record does not list analysis entries. The detailed statistical plan, including any model, transformation, handling of values below assay limits, or approach to repeated concentration measurements, is not reported in the registry record.

What can planning illustrations establish?

General: Sample-size calculations can illustrate how many participants might be needed under specified assumptions about an effect, variability, allocation, and statistical method. An illustration based on an observed effect is a planning scenario, not observed power and not evidence that the trial was designed around that effect. The registry record does not report the study’s sample-size justification or the assumptions used to choose its enrollment target. Any planning illustration should not be interpreted as a description of the trial’s original design or as a substitute for reported endpoint results.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 14 outcome measures, while the primary endpoint includes Cmax assessments for TAK-438F and the metabolites M-I, M-II, M-III and M-IV-Sul. Considering several outcomes or analytes can raise a multiplicity question when multiple statistical tests are conducted: the chance of at least one apparently notable result can increase as the number of tests increases. General: methods for addressing multiplicity may include defining a primary outcome in advance, adjusting inference across tests, or treating secondary analyses as exploratory. The appropriate approach depends on the analysis plan and purpose.

The registry record does not report a multiplicity strategy, a hierarchy among the listed outcomes, or statistical tests for the primary endpoint. It lists zero analyses. It is therefore not possible to determine from this record whether multiplicity adjustments were planned or used, or how any results across analytes and outcomes were interpreted.

The primary population is defined by drug receipt, sufficient concentration data for at least one pharmacokinetic parameter, completion of minimum procedures, and absence of significant protocol deviations. The number included in that population is not reported in the registry record. The record also does not describe missing-data handling, reasons for unavailable measurements, or whether participants with incomplete concentration profiles were excluded or otherwise handled.

General: Missing measurements can affect precision and, depending on why they are missing, can also affect the interpretation of an estimate. The amount and pattern of missingness, the analysis population, and the method used to handle unavailable values are relevant to judging results. Since the endpoint results and these details are not reported in the registry record, neither the effect of missing data nor the practical impact of multiplicity can be assessed. The reported enrollment of 33 does not, by itself, reveal the number contributing to each endpoint summary.

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 0% reporting threshold.

Most frequent non-serious adverse event terms

The registry reports serious adverse event counts by regimen group. For TAK-438 10 mg once daily, zero participants were recorded with serious adverse events among 12 at risk. For TAK-438 20 mg once daily, the corresponding figures are zero among 11. For TAK-438 20 mg twice daily, the figures are zero among 10. The registry records zero deaths in each group.

Other adverse events are listed separately: 4 participants among 12 in the 10 mg once-daily group, 6 among 11 in the 20 mg once-daily group, and 4 among 10 in the 20 mg twice-daily group. These are counts of participants affected, not a statistical comparison. No serious adverse event terms are listed among the top serious terms.

General: A recorded count of zero means no event of that category was recorded in the listed group; it does not establish that the underlying risk is zero. The group sizes are limited, and assignment was non-randomized, so these counts do not support a robust causal comparison among regimens. The registry record does not report additional detail about event timing, duration, severity grading, or attribution to study drug. The figures should be read as descriptive safety reporting rather than proof about comparative risk.

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

The record establishes that a completed Phase 1 study was conducted to examine TAK-438 pharmacokinetics in healthy adult Chinese participants. It identifies three oral regimens and defines a Day 1 maximum observed plasma concentration endpoint for TAK-438F and named metabolites. It also states the criteria for the pharmacokinetic set and reports selected adverse-event counts.

It does not report the numerical primary endpoint results. There are no registry-record means or standard deviations from which to describe observed Cmax levels or their variability. Nor are numerical estimates, confidence intervals, or tests of differences between regimens reported. The absence of these values means the registry record cannot answer how concentrations differed across the three schedules.

The design also limits comparative interpretation. Allocation was non-randomized, and the record explicitly cautions that the arms are not a like-for-like control comparison. Thus, the design description does not support treating any between-group contrast as an unbiased causal estimate. The record does not report an adjustment method that might address group differences.

General: Pharmacokinetic results describe drug concentrations over time in a defined population; they do not by themselves establish clinical benefit or harm. Interpretation also depends on sampling, assay and analysis details, population characteristics, and the completeness of results reporting. Those details cannot be filled in when they are not reported.

The safety counts show no recorded serious adverse events or deaths in the listed groups, alongside recorded other adverse events. These are descriptive registry figures, not evidence that an event cannot occur or a reliable comparison of regimen safety. The study’s healthy-participant setting and its stated pharmacokinetic purpose should also be kept distinct from claims about outcomes in a patient population. The registry record supports a bounded account of study design and reporting, not a treatment recommendation or a conclusion that TAK-438 does or does not work.

13. Why This Trial Matters Statistically

This study is statistically informative as an example of a pharmacokinetic question with a clearly named concentration endpoint and a population defined for analysis. Cmax focuses attention on the highest observed plasma concentration during a specified sampling window. Identifying the analytes, timeframe, summary measure, and population helps clarify what a reported estimate would represent.

The record also illustrates why design details matter when readers encounter several regimen groups. Although the study was parallel, allocation was non-randomized, and the record cautions against treating the groups as like-for-like controls. Statistical comparisons are not made reliable by the mere presence of multiple arms; the assignment process and analysis approach affect what conclusions can be drawn.

Equally important is the distinction between a registered endpoint definition and a reported result. The registry lists the primary measurement but provides no numerical Cmax summaries. Without the results, readers cannot evaluate magnitude, variability, or precision. The analysis-population definition is useful, but its count and participant flow are also absent, leaving uncertainty about how many participants contributed to the endpoint.

General: Transparent reporting of estimates, uncertainty, analysis populations, missing data, and multiplicity helps readers judge both statistical precision and the scope of inference. The record’s missing numerical outcomes make those assessments impossible for the primary endpoint. This is not a reason to infer a result; it is a reason to distinguish carefully between what the study was designed to measure and what the registry actually reports.

The statistical value of the record is therefore primarily descriptive: it specifies a study framework and endpoint while showing the limits of interpretation when outcome summaries and analysis details are unavailable. It also makes clear that safety counts and pharmacokinetic summaries answer different questions and should not be merged into a single conclusion.

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 central limitation for interpretation is that numerical results for the primary endpoint are not reported in the registry record. Means and standard deviations are specified as the intended summaries, but their values are absent. The number of participants in the pharmacokinetic set is also not reported, so the analysis denominator and the relationship between the enrolled group and the endpoint population cannot be established.

The study used non-randomized allocation and no masking. The registry warns that the arms are not a like-for-like control comparison. The record does not explain the allocation process or report a statistical approach for adjusting group comparisons. Consequently, the regimen groups cannot be treated as randomized comparisons on the basis of the available information.

Additional analysis details are missing: the registry record does not report the statistical analysis plan, uncertainty estimates, inferential tests, handling of missing concentration measurements, or a multiplicity strategy. The listed endpoint timeframe identifies sampling up to 48 hours but does not provide the individual sampling schedule or observed concentration profiles. These omissions constrain assessment of precision, missingness, and the interpretation of the measured maximum.

The record reports enrollment of 33 and identifies healthy participants, but it does not provide endpoint-specific denominators or participant flow. The findings therefore cannot be generalized from the record to populations or settings not described in the study. The registry also does not report a sample-size justification. Any planning illustration based on an observed effect should be understood as a scenario rather than the study’s documented design rationale or observed power.

The safety information is limited to counts of participants affected in the listed categories. Further event-level descriptions are not reported in the registry record. Together, these limits mean the record supports a design-level description and a cautious reading of safety counts, but not a quantitative evaluation of the primary pharmacokinetic findings.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: A Pharmacokinetic Study of TAK-438 in Healthy Adult Chinese Participants — NCT03085836.
• Registry record last updated 2019-01-30; status last verified 2018-08.
• Results first posted 2019-01-30.
• 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

NCT03085836 is a completed, open-label, single-center, parallel Phase 1 study of TAK-438 in healthy adult Chinese participants. It enrolled 33 participants and used non-randomized allocation across 10 mg once-daily, 20 mg once-daily, and 20 mg twice-daily regimens. The primary endpoint was Day 1 maximum observed plasma concentration for TAK-438F and metabolites M-I, M-II, M-III and M-IV-Sul, summarized by mean and standard deviation.

The registry record defines the pharmacokinetic analysis population and lists 14 outcome measures, but it reports zero analyses and no numerical primary endpoint results. Serious adverse events and deaths are recorded as zero in each regimen group; other adverse events are also listed. Because allocation was non-randomized and the record cautions that arms are not like-for-like controls, the safety counts should be treated descriptively. The endpoint values, analysis-set size, missing-data approach, multiplicity plan, and sample-size justification are not reported in the registry record.