Impact of Methylation of Acyl Glucuronide Metabolites on Incurred Sample Reanalysis Evaluation: Ramiprilat Case Study

Abstract

Following this discovery, a reproducible method was developed and successfully validated for ramipril and ramiprilat. Additional stability tests were performed in the presence of glucuronide and diketopiperazine metabolites of ramipril and ramiprilat to demonstrate the method specificity.

Analysis of Imprecision in Incurred Sample Reanalysis for Small Molecules

“…It should be noted that for majority (>50%) of ISR samples in batch B, no two assay values (i.e., original vs repeat 1, original vs repeat 2, or repeat 1 vs 2) were reproducible (data not shown). In such cases, even when the overall ISR results (i.e., after combining results from multiple ISR batches) happen to meet the ISR acceptance criterion, the accuracy of data for the subjects, whose ISR samples consistently demonstrated lack of IS reproducibility, are questionable, Although, the IS CVs and the assay CVs (based on QCs) are similar in the current ISR examples in BE studies, there are instances when IS imprecision do not mimic assay imprecision in BE or PK studies (3,4,17). This is the reason why imprecision in the current paper differentiates between ISR imprecision and assay imprecision.…”

“…In addition, the isolated errors in study samples may not be reflected in the calibration standard and QC samples (i.e., spiked samples), especially when the ratio of study samples to spiked samples are high. In fact, for the majority of ISR failures reported, retrospective review of spiked samples rarely indicates problems in spiked samples (3,4). In such cases, an increase in ISR sample size will be useful.…”

“…However, over the last few years, there have been several observations that indicate monitoring performance of QCs may not always guarantee assay performance during analysis of study samples. Broadly, several factors including assay conduct, drug characteristics, and matrix effects may contribute to the above discrepancy (1)(2)(3)(4). The concept of incurred samples reanalysis (ISR) was discussed at the American Association of Pharmaceutical Scientists (AAPS) workshop in Crystal City, VA in 2006 and other meetings as a tool to confirm the reliability of the bioanalytical methods during analysis of study samples (5).…”

Potentially New Isobaric Metabolite of Fluvastatin Observed by LC–MS/MS During Incurred Sample Analysis

“…Samples were collected during two consecutive days at specific times before (pre-dose) and after the dose administration. Collection times were: 0, 1, 2, 3, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8,9,10,12,16,24,28, 32 and 36 h. After collection, blood samples were centrifuged at a temperature of 4°C (1500 × g for 10 min). The plasma obtained was transferred into polypropylene culture tubes and stored at a temperature of -20°.…”

“…These metabolites may convert into their parent drugs through in-source collision-induced dissociation (CID) [7][8][9][10][11][12] or under sample collection, storage, extraction and injection conditions [13][14][15][16][17]. Prior to method development, an extensive literature search was performed to identify all possible FV metabolites and determine their impact on the selectivity of the FV bioanalytical method.…”