Chiral Analysis of d- and l-Ritalinic Acids in Biological Samples and the Stereoselective Metabolism of d- and l-Methylphenidate
Bibliographic record
Abstract
This research work has been aimed at developing a chiral separation method for d- and l-ritalinic acids, and applying it to in vitro and in vivo studies on the enantioselective metabolism study of methylphenidate. Three chiral methods for the separation of d- and l-ritalinic acids have been investigated, and the al-acid glycoprotein method was demonstrated to be the best one for the quantitative analysis of ritalinic acids in biological samples. In addition, the in vitro enantioselective hydrolysis of methylphenidate was investigated using enzymes obtained from a commercial source, E-3128 (esterase from porcine liver), dog liver, human and dog plasma. Results clearly demonstrate that the enzymes from different sources exhibited differences in stereoselectivity. It appears that the esterase(s) in liver give preference to the 1-enantiomer of methylphenidate, and in contrast, the esterase(s) in plasma prefer the d-enantiomer. The in vivo pharmacokinetics was studied using four phases of intravenous administration of methylphenidate. It was demonstrated that there were stereoselective differences in the plasma concentrations and in the various pharmacokinetics parameters calculated. Results revealed that the clearance of the 1-methylphenidate was significantly greater than that of its d-antipode, which is consistent with previous reports obtained by measuring the remaining concentration of methylphenidate enantiomers. Combining with the in vitro results that there was the different enantiomeric preference in human plasma and the same preference in liver homogenates, it suggests that the hydrolysis of methylphenidate in humans mainly occurs in the liver. In conclusion, a new chiral method has been developed and validated for the quantitative analysis of enantiomeric ritalinic acids, and furthermore, it was successfully applied for the in vitro hydrolysis and in vivo pharmacokinetics of methylphenidate.
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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) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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".