Source-backed half-life profile
Ketamine half-life calculator
Ketamine is a useful reminder that a parent compound and its metabolites can tell different stories.
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 curve gives a clean visual for parent-drug decline, while effects and metabolite exposure may not line up neatly with that curve.
Source angle
Read for analyte and sampling details: ketamine, norketamine, route, and clinical context should not be treated as interchangeable.
Do not use it for
Do not use the page to estimate anesthesia, impairment, dissociation, recovery, or clinical monitoring.
Best next step
Open norketamine next, then read the active-metabolite guide.
Ketamine: evidence and interpretation notes
The label value is a redistribution phase
Ketamine injection labeling describes a beta half-life of about 2.5 hours. HalfLifeDB uses that value because it is clearly identified and tied to an official formulation, but the wording matters: this is a redistribution-phase value, not a claim that every study, route, or patient has one universal terminal half-life.
Ketamine distributes rapidly and is converted to metabolites including norketamine. A one-line parent curve cannot represent both the early movement between compartments and the later appearance and decline of active metabolites.
| Evidence source | What it contributes | Important limit |
|---|---|---|
| DailyMed injection labeling | The 2.5-hour beta-phase value used by the chart | It is formulation- and phase-specific rather than a universal terminal estimate |
| Hijazi intensive-care study | Ketamine and metabolite measurements in 12 patients with brain or spinal injury | A specialized critical-care population should not be generalized to healthy volunteers |
| StatPearls clinical reference | Broad pharmacology and norketamine context | It summarizes evidence rather than supplying the plotted value |
| PubChem identity record | Compound identity | It does not support phase selection |
A specialized study tells a different distribution story
Hijazi and colleagues measured ketamine, norketamine, and dehydronorketamine in 12 intensive-care patients. They reported a mean estimated elimination half-life of 4.9 hours with substantial variability. Both clearance and volume of distribution were higher than values described in healthier or surgical populations, and the larger change in distribution volume produced the longer estimate.
That does not invalidate the 2.5-hour label value. It demonstrates that the numbers answer questions in different settings and may emphasize different portions of a multi-phase profile. HalfLifeDB keeps the ICU result in view instead of averaging unlike populations into an artificial midpoint.
What to carry away from the chart
The displayed line is a readable model of the labeled beta phase for parent ketamine. It can support comparison with other reviewed curves and show why a few hours of half-life produces a much longer mathematical tail than a minutes-scale entry.
It cannot estimate anesthesia, dissociation, recovery, impairment, or metabolite exposure. Route, population, sampling duration, distribution, and norketamine all matter. Ketamine is a useful example of why the phase label beside a half-life number can be as important as the number itself.
Reading this curve
HalfLifeDB uses 2.5 h as a representative input for Ketamine beta (redistribution) phase. In the simplified model, about 0.1% remains after 24 hours and about 3% remains after five half-lives, or roughly 12.5 h.
This is a short curve. The modeled amount changes noticeably over the same day, while effects, metabolites, and safety questions can still follow a different timeline. The curve is relative: it does not estimate a person's measured concentration, effects, impairment, or time to clearance.
dissociative context
Dissociative entries often require care because parent compounds, metabolites, redistribution, and subjective duration may not move together.
- The calculator does not model active metabolites separately.
- Duration and half-life can diverge substantially.
- Study values may depend on route and sampling window.
Ketamine timeline checkpoints
| Elapsed time | Modeled remaining | Reading note |
|---|---|---|
| 6 h | 18.9% | Long-tail portion of the model |
| 12 h | 3.59% | Low modeled remainder, not a clearance guarantee |
| 24 h | 0.13% | Low modeled remainder, not a clearance guarantee |
| 2.0 days | 0.00% | Low modeled remainder, not a clearance guarantee |
| 3.0 days | 0.00% | Low modeled remainder, not a clearance guarantee |
Nearby profiles by half-life
These entries sit near Ketamine within the dissociative 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 | 2.5 h |
|---|---|
| Modeled analyte or phase | Ketamine beta (redistribution) phase |
| Curve type | Normalized, first-order decline |
Selection note: The linked injection labeling describes 2.5 hours as the beta-phase redistribution half-life, not a universal terminal value across routes.
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.
- Clinical reference Rosenbaum SB et al. Ketamine. StatPearls.Clinical reference used for broad pharmacology and metabolite context; not the sole basis for the selected phase value.
- Research abstract Hijazi Y et al. Pharmacokinetics of ketamine in intensive care patients (2003).Twelve-patient intensive-care study reporting a longer 4.9-hour estimate and illustrating population-dependent distribution.
- Official labeling DailyMed label: Ketamine hydrochloride injection.Official injection labeling that describes the 2.5-hour beta redistribution half-life modeled here.
- Identity record PubChem Compound Summary: Ketamine.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 dissociative 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.