Mechanism of the first and second peaks in epinephrine pharmacokinetics over time
Bibliographic record
Abstract
Abstract Background: There is a documented double peak phenomenon following the intramuscular injection of epinephrine, however these peaks are typically representative of mean epinephrine concentrations and not individual subjects. Objective: An examination of epinephrine pharmacokinetics was conducted to explore the nature of the double peak phenomenon and to determine if the double peaks observed in mean concentration profiles were also observed in individual subjects. Methods: A GCP compliant study was conducted in 36 adult volunteers with a history of type I allergies. Blood samples were collected before and at multiple timepoints after subjects self- administered two FDA-approved epinephrine auto-injectors (EpiPen 0.3 mg and Symjepi 0.3 mg). Pharmacokinetic parameters (Cmax and tmax) and concentration-time curves were determined based on individual subjects. Subjects were categorized by their tmax (≤4 min, >4 min - ≤10 min, >10 min - ≤20 min, >20 min - ≤30 min, >30 min - ≤45 min, and >45 min, presented as ≤4 min, ≤10 min, ≤20 min, ≤30 min, ≤45 min, and >45 min, respectively). Results: The majority of individual subjects did not have double peaks. Double peaks in mean concentration-time profiles were observed when tmax was ≤4 min following EpiPen and Symjepi, tmax ≤30 min following EpiPen, and tmax ≤45 min following EpiPen. The individual epinephrine concentration curves for subjects with a tmax ≤4 min following EpiPen and Symjepi and tmax ≤45 min following EpiPen demonstrate that the majority of individual subjects do not have double peaks. Conclusion: These data suggest that the double peaks observed in mean epinephrine concentrations are likely driven by subsets of subjects with either early or late tmax values and may not necessarily be a pharmacokinetic characteristic of epinephrine.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".