Source-backed half-life profile
Modafinil half-life calculator
Modafinil is a long wakefulness-promoting curve where the practical question is often sleep timing, not just concentration decline.
Every curve begins at 100%. No dose or measured body concentration is assumed.
X-axis: elapsed time. Y-axis: modeled percentage of the relative starting point remaining. This is a mathematical visualization, not a personal concentration estimate.
What a careful reader should notice first
The model makes persistence visible, but alertness, insomnia, performance, and side effects do not follow one smooth line for everyone.
Source angle
Read labeling and study context for formulation, metabolites, and population details before generalizing.
Do not use it for
Do not use the chart to decide sleep timing, work safety, dose timing, or medical suitability.
Best next step
Compare with caffeine and amphetamine, then read half-life-versus-duration.
Modafinil: evidence and interpretation notes
The 15-hour value describes repeated administration
Modafinil labeling reports an effective elimination half-life of about 15 hours after multiple doses. A double-blind study in healthy male volunteers also characterized steady-state pharmacokinetics with a roughly 15-hour half-life. Those two sources are the direct reason this page uses 15 rather than selecting a shorter single-dose estimate.
A clinical pharmacokinetics review places the broader elimination range around 12 to 15 hours and reports that steady state is generally reached within several days. The agreement across labeling, controlled study, and review makes 15 hours a defensible representative value while preserving the repeated-administration label in the model name.
| Evidence source | What it contributes | Important limit |
|---|---|---|
| DailyMed labeling | Official 15-hour effective value after multiple dosing | It should not be presented as a universal single-dose result |
| Wong controlled study | Repeated-administration measurements in healthy male volunteers | The selected population was narrow |
| Robertson pharmacokinetics review | Absorption, 12-to-15-hour range, metabolism, and enantiomer context | The authors were affiliated with the manufacturer, a relevant provenance detail |
| PubChem identity record | Compound identity | It does not establish the 15-hour value |
A racemic compound does not have one simple component curve
Modafinil contains two enantiomers whose pharmacokinetics differ. The review explains that the longer-lived enantiomer contributes heavily to the terminal profile. Modafinil is primarily eliminated through metabolism, with less than 10% excreted unchanged, and its major metabolites do not share exactly the same time course as the parent mixture.
The page does not split the two enantiomers or metabolites into separate lines. Its 15-hour curve is therefore a practical effective profile for the labeled product after repeated administration, not a chiral pharmacokinetic model.
Persistence is not productivity
The long modeled tail helps explain why modafinil is pharmacokinetically distinct from caffeine and shorter stimulants. It cannot predict alertness, insomnia, sleep quality, work performance, adverse effects, or medical suitability. Those outcomes involve pharmacodynamics, health status, timing, and individual response.
The chart supports comparison and persistence literacy. Decisions about use, timing, interactions, or treatment belong with the prescribing information and a qualified clinician rather than a remaining-percentage calculation.
Reading this curve
HalfLifeDB uses 15 h as a representative input for Modafinil after multiple dosing. In the simplified model, about 33.0% remains after 24 hours and about 3% remains after five half-lives, or roughly 3.1 days.
This is a day-scale half-life. Repeated exposure, timing, and source context start to matter more than a single snapshot of the curve. The curve is relative: it does not estimate a person's measured concentration, effects, impairment, or time to clearance.
wakefulness-promoting agent context
Wakefulness-promoting entries can have long functional tails where alertness, sleep disruption, and concentration decline do not map neatly onto one another.
- Half-life is not a sleep-quality or performance estimate.
- Route, formulation, metabolites, and timing can change interpretation.
- Clinical use and adverse-effect questions require source-specific context.
Modafinil timeline checkpoints
| Elapsed time | Modeled remaining | Reading note |
|---|---|---|
| 12 h | 57.4% | Meaningful modeled decline, not near-zero |
| 24 h | 33.0% | Long-tail portion of the model |
| 2.0 days | 10.9% | Long-tail portion of the model |
| 3.0 days | 3.59% | Low modeled remainder, not a clearance guarantee |
| 5.0 days | 0.39% | Low modeled remainder, not a clearance guarantee |
Nearby profiles by half-life
These entries sit near Modafinil within the wakefulness-promoting agent group when sorted by representative half-life. That makes them curve comparisons, not statements about equal potency, effects, or risk.
No nearby published profiles are available in this category.
Pharmacokinetics at a glance
| Representative half-life | 15 h |
|---|---|
| Modeled analyte or phase | Modafinil after multiple dosing |
| Curve type | Normalized, first-order decline |
Selection note: The linked product labeling reports an effective elimination half-life of about 15 hours after multiple doses.
Sources and evidence context
A linked record is not automatically proof of the displayed value. Study, labeling, review, and compound identity sources serve different purposes; notes below identify limitations when they are known.
- Official labeling DailyMed label: Modafinil tablet.Official labeling supporting an effective elimination half-life of about 15 hours after multiple dosing.
- Research abstract Robertson P Jr, Hellriegel ET. Clinical pharmacokinetic profile of modafinil (2003).Clinical pharmacokinetics review describing 12-to-15-hour elimination, enantiomer behavior, absorption, and metabolism.
- Research abstract Wong YN et al. Ascending-dose pharmacokinetics of modafinil in healthy volunteers (1999).Double-blind repeated-administration study in healthy male volunteers reporting a roughly 15-hour steady-state half-life.
- Identity record PubChem Compound Summary: Modafinil.Compound identity record; background only.
What this page does not answer
- It does not estimate impairment, intoxication, or fitness to drive.
- It does not predict urine, blood, saliva, or hair test results.
- It does not model repeated exposure, tolerance, withdrawal, or interactions.
- It does not replace clinician, pharmacist, toxicologist, or emergency guidance.
Continue with context
- All substance profiles
- Browse the wakefulness-promoting group
- Compare this curve
- Clearance and volume of distribution
- Bioavailability, route, and formulation
- Active metabolites and parent compounds
- First-order vs nonlinear kinetics
- Detection windows vs half-life
- Reading labels and source quality
Read the medical disclaimer, methodology, and profile review log before using the model for comparison.