Urinary Excretion Kinetics of Salbutamol and Its Sulfoconjugated Main Metabolite After Oral and Inhalative Administration of Racemic Salbutamol or Levosalbutamol
Bibliographic record
Abstract
It was the aim of this study to compare the ratio of salbutamol and its major metabolite salbutamol-4’-O-sulfate as well as the quantity excreted renally after oral and inhalative administration. Additionally, the excretion pattern after application of racemic salbutamol opposed to the pure enantiomer levosalbutamol was evaluated. For quantitation of the sulfonated metabolite of salbutamol, reference material was synthesized and characterized by NMR and HRMS. Urine samples were analyzed by ultrahigh performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). Salbutamol is mainly metabolized by sulfotransferase 1A3 (SULT1A3), which is most abundantly found in the jejunum. A high first pass effect occurs upon oral administration, which leads to a higher amount of salbutamol-4’-O-sulfate in urine compared to unchanged salbutamol excreted within the first hour post administration. Thus, when administered orally, the proportion of metabolite to total salbutamol was higher than for inhalative administration in the early urinary excretion. Levosalbutamol is the favored enantiomer of SULT1A3 and therefore metabolized at a higher rate whereas racemic salbutamol shows a reduced proportion between metabolite and parent compound. The amount of sulfoconjugate was found higher than that of the parent compound for all urine samples except for those excreted in the first hour after inhalative administration.
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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 | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
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".