Study of Prasugrel in Korean Healthy Male Volunteers: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Study of Prasugrel in Korean Healthy Male Volunteers (NCT01591317), a randomized phase 1 study. The primary outcome is Pharmacokinetics (PK): Area Under the Concentration Curve (AUC) of Prasugrel's Active Metabolite R-138727 During Loading Dose.

2. Clinical Question

The study’s stated purpose was to investigate how the body processes prasugrel and how it affects blood clotting in healthy Korean men, while also collecting side-effect information. The primary endpoint is pharmacokinetic: it describes active-metabolite exposure over time, rather than a clinical health outcome. The record also lists pharmacodynamic outcomes concerning ADP-induced platelet aggregation and inhibition of Verify Now P2Y12 reaction units.

The primary results present geometric mean AUC values for the two listed dose groups. Those values describe exposure in the recorded groups; they do not, on their own, establish a causal difference between regimens. The registry record does not report a formal comparison estimate, confidence interval, or p-value for the primary endpoint. The distinction between the two primary result entries and the three regimen descriptions also means the posted values cannot be assigned to each maintenance-dose regimen separately from the information recorded.

3. Trial Design

This was a phase 1, randomized, parallel-group study listed as completed. The registry record gives an enrollment of 30 and describes the participants as healthy Korean men. Masking is listed as none, so the study is recorded as unmasked. The record gives a start date of 2009-03 and a primary completion date of 2009-05.

Three prasugrel regimens appear in the arm descriptions. Each began with one oral loading dose and continued with once-daily oral maintenance dosing for 10 days. The regimens were 60 mg followed by 10 mg, 30 mg followed by 7.5 mg, and 30 mg followed by 5 mg. These are different dosing schedules, not a placebo-versus-treatment comparison. No separate untreated or placebo arm is listed.

The primary endpoint results are organized as two entries: Prasugrel 60 mg, with 10 participants, and Prasugrel 30 mg, with 20 participants. The three regimen descriptions and the two primary-result entries do not align one-to-one in the registry record. In particular, the record does not explain whether or how the 20 participants listed under Prasugrel 30 mg are divided between the 30 mg/7.5 mg and 30 mg/5 mg schedules. The safety results, in contrast, are reported for all three regimen groups, with 10 participants at risk in each.

The randomized, parallel structure indicates assignment to groups rather than a reported within-participant crossover. The registry record does not describe the randomization procedure, allocation concealment, or the rationale for the group sizes. A detailed protocol, statistical analysis plan, and sample-size justification are not reported in the registry record. The available information therefore supports a description of the planned dosing groups and posted outcomes, but not a reconstruction of all design or analysis decisions.

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.

Overall Study

Analysis population for the primary outcome, as defined in the registry: All randomized participants

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.

6. Primary Endpoint

The registry lists the primary outcome as Pharmacokinetics (PK): Area Under the Concentration Curve (AUC) of Prasugrel's Active Metabolite R-138727 During Loading Dose, measured over Day 1 predose up to 24 hours post dose.

The primary endpoint is the area under the plasma concentration curve for prasugrel’s active metabolite R-138727 during the loading dose. The stated interval runs from predose on Day 1 through 24 hours after the dose. More specifically, the description defines the measure as the area from time zero to the last quantifiable plasma concentration, tlast. The unit is nanogram times hour per milliliter (ng*h/mL).

In general, an area under a concentration-time curve combines concentration and time into a measure of drug exposure over the observed interval. A larger AUC indicates a larger measured concentration-time area for that interval, but interpretation depends on the dose, sampling interval, and how the measure is defined. It is not itself a clinical outcome or a direct measure of platelet response.

The registry reports the endpoint as a geometric mean with geometric coefficient of variation as its dispersion measure. In general, geometric summaries are used for positive measurements that may be right-skewed or naturally interpreted multiplicatively. The posted geometric mean values are 600.0 ng*h/mL for Prasugrel 60 mg and 283.0 ng*h/mL for Prasugrel 30 mg. The corresponding geometric coefficients of variation are 16.0 and 17.0. No confidence intervals or formal statistical comparison for this endpoint are reported in the registry record.

Pharmacokinetic exposure is useful for characterizing what happens to a drug and its active metabolite after dosing. The record also lists platelet-related pharmacodynamic outcomes, which address biological response. Neither type of measure alone establishes a clinical benefit or harm in a patient population.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry identifies the primary endpoint statistic as a geometric mean and reports a geometric coefficient of variation for each listed group. These summaries describe the distribution of positive concentration-derived measurements in a way that differs from an arithmetic mean and standard deviation. In general, a geometric mean is obtained by working on the logarithmic scale and transforming the average back to the original scale. It is often useful when observations are right-skewed or when proportional rather than additive differences are meaningful. The registry record does not report the individual measurements or the detailed calculation procedure.

A geometric coefficient of variation is a measure of relative spread associated with a geometric summary. It describes variability in relation to the scale of the observations rather than giving a spread in the original unit in the same way as a standard deviation. The recorded values are 16.0 for the Prasugrel 60 mg group and 17.0 for the Prasugrel 30 mg group. The exact method used to estimate these quantities is not reported in the registry record. The coefficient is not a confidence interval and does not provide the uncertainty of a difference between groups.

What does the AUC measure?

The area under the concentration-time curve integrates measured concentrations across a specified time interval. In this study, the interval is described as Day 1 predose up to 24 hours after the loading dose, with the AUC defined through the last quantifiable plasma concentration, tlast. In general, this summarizes exposure across the observed interval rather than relying on a single blood concentration. It depends on the measurement schedule and endpoint definition, so it should not be confused with total exposure over an unspecified or longer period.

The endpoint is measured for the active metabolite R-138727, rather than being a direct measure of platelet aggregation. The record separately lists pharmacodynamic outcomes involving ADP-induced P2Y12 receptor-mediated platelet aggregation and percent inhibition of Verify Now P2Y12 reaction units. Those outcomes concern biological response, while AUC concerns pharmacokinetic exposure. The record does not give numerical results for those secondary outcomes in the registry record for this analysis.

How should group summaries be compared?

Descriptive group summaries can show the observed scale of measurements, but a formal comparison needs an estimate of the contrast and an account of its uncertainty. For example, a confidence interval would describe uncertainty around an estimated contrast under the analysis method, while a p-value would address compatibility with a specified null hypothesis under that method. Neither is reported for the primary endpoint in the registry record. No comparison should be reconstructed from the posted geometric means and coefficients of variation unless an analysis is explicitly labelled as recalculated; no such recalculated contrast is included in the registry record.

The record marks the trial as randomized and parallel. In general, random allocation can support comparison between assigned groups by reducing systematic differences in expectation, but the details of the randomization procedure are not reported. The study is unmasked. The record does not report whether laboratory measurements or outcome assessments were blinded, so no further claim about masking of measurement can be made.

What can the group sizes tell the reader?

The primary results list 10 participants in the Prasugrel 60 mg group and 20 in the Prasugrel 30 mg group. Group size is relevant to the amount of information available, but it is not a measure of observed effect or a guarantee of precision. The registry record does not give a sample-size justification or a planned precision target. It also does not report a confidence interval for either mean or for their contrast. The record’s total enrollment is 30, while safety results are presented across three regimen groups of 10 participants each.

The distinction between the primary results and the regimen descriptions matters methodologically. The primary result labels divide participants into a 60 mg and a 30 mg entry, whereas the study description identifies two 30 mg loading schedules with different maintenance doses. Since the record does not explain the relationship between the 20-person entry and those schedules, the result cannot support a regimen-specific interpretation for each of the two 30 mg schedules.

What analysis details are unavailable?

The registry record lists zero analyses and does not report a statistical analysis plan. It does not state whether the primary endpoint was analyzed on a logarithmic scale, which model was used, whether covariates were included, or how any missing measurements were handled. These details should not be inferred from the use of a geometric mean. Nor does the record report interim analyses, adjustment for multiple comparisons, or a prespecified hypothesis-testing procedure.

The record also includes a general planning framework based on an observed effect, equal allocation, a two-sided significance level of 0.05, and a normal approximation. No resulting planning counts are stated in the registry record for interpretation. Such planning illustrations, when present, are not observed power and do not substitute for the trial’s own design justification or for uncertainty intervals around the actual results.

In general, multiplicity arises when several hypotheses or outcomes are examined, because repeated testing can increase the chance of at least one apparently notable result. The registry lists eight outcome measures and two named secondary outcomes, but it does not report a multiplicity strategy. That absence means it is not possible to determine whether or how multiplicity was addressed. It also does not establish that every outcome was formally tested.

10. Multiplicity, Missing Data and Analysis Populations

The registry record names a primary pharmacokinetic endpoint and lists eight outcome measures overall, including two named pharmacodynamic secondary outcomes. It does not report a multiplicity adjustment or an analysis plan describing how primary and secondary outcomes were handled. In general, when several outcomes or comparisons are examined, multiplicity methods can control the chance of false-positive findings across a defined family of tests. Whether such methods were used in this study is not reported in the registry record.

The record lists zero analyses and provides no primary-endpoint confidence interval or p-value. The absence of recorded analyses is not evidence that no analyses occurred; it means the registry record does not document them in the available results information. No interim-analysis plan or stopping rule is reported.

The primary endpoint population is described as all randomized participants. The record does not describe exclusions, the number of participants with evaluable pharmacokinetic measurements, or how missing concentration samples or endpoint values were handled. Thus, the relationship between the stated analysis population and the measurements contributing to each geometric mean is not fully documented. Missing-data methods, imputation procedures, and sensitivity analyses are not reported in the registry record.

The result labels also leave an analysis-population question unresolved: a 20-participant Prasugrel 30 mg primary-result group is reported, while the regimen descriptions list two distinct groups with a 30 mg loading dose. The record does not explain how participants or measurements from those regimens were combined for the posted primary result. These gaps limit assessment of the analysis without indicating that a particular method or omission occurred.

11. Safety Results

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

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 safety results are reported separately for the three listed dosing regimens. Each group has 10 participants at risk for serious adverse events, and the number affected by a serious adverse event is 0 in each group. The record lists no serious adverse-event terms. These figures describe the recorded serious-event counts in this study; they do not establish that the risk of serious events is absent.

The death counts are not reported in the registry record. The record also gives counts for other, non-serious adverse events: 3 participants in the 60 mg/10 mg group, 4 in the 30 mg/7.5 mg group, and 3 in the 30 mg/5 mg group. These are group counts, not a formal comparison of safety between regimens. The registry record does not provide confidence intervals or statistical tests for these safety counts.

Safety counts from a study of this size should be read as descriptive observations. A count of zero serious events in a group does not demonstrate that an event could not occur, and the figures do not establish comparative safety. The registry’s listed event counts also do not describe severity, timing, duration, or the relationship judged between each event and prasugrel beyond the information recorded.

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

The posted results describe active-metabolite exposure during a defined loading-dose interval in healthy Korean male volunteers. The geometric mean AUC was 600.0 ng*h/mL for the Prasugrel 60 mg group and 283.0 ng*h/mL for the Prasugrel 30 mg group. These summaries give a descriptive account of the measurements recorded for those entries, alongside geometric coefficients of variation of 16.0 and 17.0.

They do not establish a formal difference between dose groups. No contrast estimate, confidence interval, or p-value is reported for the primary endpoint. The record also does not explain how the 20 participants in the Prasugrel 30 mg result entry relate to the two 30 mg loading-dose regimens with different maintenance doses. Accordingly, the posted value cannot be interpreted as a separate estimate for each of those regimens.

The primary endpoint is pharmacokinetic, not a clinical outcome. It characterizes exposure to an active metabolite over the specified interval; it does not, by itself, show a change in platelet function or a health outcome. Although the registry lists two platelet-related secondary outcomes, numerical results for them are not included in the registry record. The study’s stated interest in side effects is reflected in the recorded safety counts, but those counts are descriptive and do not establish comparative safety.

The study population and setting also bound interpretation. The record describes healthy volunteers, not patients receiving treatment for a condition. The results therefore cannot establish outcomes in other populations. More broadly, a small phase 1 study with no reported inferential analysis can characterize recorded measurements but offers limited evidence for claims beyond those measurements. The appropriate reading is specific: the registry records these exposure summaries and safety counts for the listed groups, while leaving important comparison and analysis details undocumented.

13. Why This Trial Matters Statistically

This study illustrates a distinction central to clinical biostatistics: a measured pharmacokinetic endpoint is not the same as a clinical outcome. The AUC summarizes active-metabolite exposure across a defined interval, while the listed platelet outcomes concern pharmacodynamic response. Keeping those questions separate prevents an exposure result from being interpreted as evidence about clinical benefit or harm.

It also shows why treatment-group labels and analysis populations need to align clearly. Three dosing schedules are described, but the primary endpoint is reported under two result labels. Because the 30 mg result includes 20 participants and the record does not explain its relationship to the two 30 mg schedules, a reader cannot assign that summary to each schedule individually. Clear reporting of the connection between assigned regimens and analyzed groups is essential for interpretable comparisons.

Another statistical lesson is that descriptive summaries are not substitutes for uncertainty estimates. Geometric means and coefficients of variation communicate the scale and variability of measurements, but without a contrast and its uncertainty they do not quantify how precisely groups differ. The record also illustrates the difference between outcomes being named and outcomes having results and analyses documented: eight outcome measures are listed, while no analyses are recorded and numerical results for the named secondary outcomes are absent in the registry record considered.

Finally, the safety counts show the limits of interpreting zero observed events. A zero count in a small group is a statement about what was recorded in that group, not proof that the event is impossible or that regimens are equivalent in safety. These principles apply broadly when reading early-phase registry results: define the population and endpoint, trace each result to its group, distinguish description from inference, and keep conclusions within the evidence actually documented.

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 main interpretive limitation is the mismatch between three described dosing regimens and two primary-result group labels. Although the primary results list Prasugrel 60 mg and Prasugrel 30 mg, the record does not say how the 20-person 30 mg entry corresponds to the two regimens that differ in maintenance dose. Regimen-specific interpretation of that result is therefore not possible from the registry record.

The primary endpoint results are descriptive. The record does not report a between-group estimate, confidence interval, or p-value, and it does not document a statistical analysis plan. The method used to calculate the geometric summaries beyond their stated statistical form is not reported. The data needed to assess individual observations, missing measurements, or distributional features are also not reported.

Although the primary population is specified as all randomized participants, the record does not state how many had evaluable endpoint measurements or how missing values were handled. It does not report exclusions or sensitivity analyses. The record names two secondary pharmacodynamic outcomes but includes no numerical results for them in the registry record considered. It also does not document a multiplicity strategy for the eight outcome measures.

The study enrolled healthy Korean men and is listed as phase 1, so its results are specific to the described population and setting. The registry does not report a sample-size justification, randomization procedure, allocation concealment, or details of laboratory masking. Safety is summarized by group counts, without uncertainty estimates or comparative tests; death counts are not reported in the registry record. These limitations restrict interpretation without implying that unreported procedures or analyses did not take place.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Study of Prasugrel in Korean Healthy Male Volunteers — NCT01591317.
• Registry record last updated 2012-10-04; status last verified 2012-09.
• Results first posted 2012-10-04.
• 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

NCT01591317 is a completed, randomized, unmasked, parallel phase 1 study of prasugrel in healthy Korean male volunteers, with enrollment of 30. The listed schedules used single oral loading doses followed by once-daily oral maintenance dosing for 10 days.

The primary endpoint was active-metabolite R-138727 AUC during the loading dose, from Day 1 predose to 24 hours after dosing. The registry reports geometric mean values of 600.0 ng*h/mL for Prasugrel 60 mg and 283.0 ng*h/mL for Prasugrel 30 mg, with geometric coefficients of variation of 16.0 and 17.0. It does not report a formal comparison or clarify how the 30 mg result group maps to the two 30 mg regimens.

Serious adverse events affected 0 participants in each of the three regimen groups, each of which had 10 participants at risk. The registry record does not report death counts. It lists pharmacodynamic secondary outcomes, but their numerical results, missing-data methods, multiplicity strategy, and statistical analysis plan are not reported in the registry record.