Simultaneous quantification of cyclosporin, tacrolimus, sirolimus and everolimus in whole blood by UHPLC-MS/MS for therapeutic drug monitoring

Lack of Interchangeability Between 3 Different Methods for Quantification of Everolimus in Blood: ACMIA, LTIA, and UHPLC-MS/MS

BACKGROUND

Affinity chrome-mediated immunoassays (ACMIA) do not require pretreatment and have a wide calibration range and good analytical performance. To date, no studies have compared ACMIA and latex agglutination turbidimetry immunoassays (LTIA). The objective of this study was to evaluate the interchangeability of ACMIA, LTIA, and the previously developed ultra-high-performance liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS).

METHODS

A total of 111 whole blood samples were collected from 25 patients undergoing routine everolimus therapeutic drug monitoring. The interchangeability between the 3 methods was assessed using robust Passing-Bablok regression analysis and Bland-Altman plots.

RESULTS

All samples were quantifiable by UHPLC-MS/MS, whereas 56 and 1 samples were below the lower limits of quantification by LTIA and ACMIA, respectively. In the robust Passing-Bablok regression plots, the slopes of the regression equations between ACMIA and UHPLC-MS/MS, LTIA and UHPLC-MS/MS, and ACMIA and LTIA were 1.23 (95% [confidence interval] CI, 1.13-1.33), 0.67 (95% CI, 0.57-0.77), and 1.71 (95% CI, 1.43-2.33), respectively, with significant proportional biases indicating no interchangeability among all 3 methods. Bland-Altman plots also revealed statistically significant proportional biases between ACMIA and UHPLC-MS/MS (P = 0.012), LTIA and UHPLC-MS/MS (P < 0.001), and ACMIA and LTIA (P < 0.001).

CONCLUSIONS

Statistically significant proportional biases were observed among the 3 methods. Blood everolimus concentration measurements should be interpreted with caution when switching the quantification methods for therapeutic drug monitoring.

Non-immobilized GO-SELEX screening of aptamers against cyclosporine A and its application in a AuNPs colorimetric aptasensor

Cyclosporine A (CsA) is an immunosuppressive drug that is widely used in clinical practice. Due to its narrow therapeutic window and the significant differences between individuals, the therapeutic drug monitoring (TDM) of CsA is required to ensure patient safety. In this study, we screened a novel aptamer, named CsA7, which could specifically recognize CsA, and developed a AuNPs colorimetric aptasensor for the rapid detection of CsA. In the SELEX process, after eight rounds of screening, four aptamer candidate sequences were obtained and subjected to binding affinity and specificity tests. Finally, the CsA7 aptamer (Kd = 41.21 ng mL-1) showed the highest affinity for CsA. Based on CsA7, we also developed a AuNPs colorimetric aptasensor, which had a detection limit of 0.1 ng mL-1 and a quantitative range of 0.1-500 ng mL-1 and showed good selectivity among CsA and its analogs. According to the results, the CsA7 aptamer provides an alternative recognition molecule to the antibody in biosensor applications and shows great potential for the rapid and convenient detection of CsA.

Development of UHPLC-MS/MS method for simultaneous determination of tacrolimus and sirolimus in human whole blood and comparisons with two immunoassays

Tacrolimus (TAC) and sirolimus (SIR) antirejection medications are widely used in organ transplantation. We aimed to develop an ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) assay for quantifying TAC and SIR simultaneously and evaluating agreement with chemiluminescence microparticle immunoassay (CMIA) and electrochemiluminescence immunoassay (ECLIA). Whole blood samples collected from 209 TAC and 208 SIR patients were assessed by UHPLC-MS/MS, CMIA and ECLIA. The agreement of the three techniques was assessed using the Bland-Altman plot. The UHPLC-MS/MS assay had a calibration range of 1-100 ng/ml for TAC and SIR. The accuracy and precision were -2.73-4.32% and <4.71% for TAC, respectively, and 0.07-4.84% and <6.5% for SIR, respectively. The three methods had good correlation. In comparison with UHPLC-MS/MS, two immunoassays showed a slight deviation in proportion. An UHPLC-MS/MS method for simultaneously detecting TAC and SIR in human whole blood was developed, validated and comparatively analyzed with CMIA and ECLIA. For determining TAC and SIR, immunoassays displayed acceptable analytical performances in terms of precision and correlation compared with UHPLC-MS/MS. However, further investigation is warranted to examine the novel method.

Monitoring of sirolimus in the whole blood samples from pediatric patients with lymphatic anomalies

In recent years, off-label use of sirolimus (SIR) has been gaining attention in the clinical practice. However, since it is critical to achieve and maintain therapeutic blood levels of SIR during treatment, the regular monitoring of this drug in individual patients must be implemented, especially in off-label indications of this drug. In this article, a fast, simple, and reliable analytical method for determining SIR levels in whole blood samples is proposed. Sample preparation based on dispersive liquid-liquid microextraction (DLLME) followed by liquid chromatography-mass spectrometry (LC-MS/MS) was fully optimized toward the analysis of SIR and proposed as a fast, simple, and reliable analytical method for determining the pharmacokinetic profile of SIR in whole-blood samples. In addition, the practical applicability of the proposed DLLME-LC-MS/MS method was evaluated by analyzing the pharmacokinetic profile of SIR in whole blood samples obtained from two pediatric patients suffering from lymphatic anomalies, receiving this drug as off-label clinical indication. The proposed methodology can be successfully applied in routine clinical practice for the fast and precise assessment of SIR levels in biological samples, thus allowing SIR dosages to be adjusted in real time during pharmacotherapy. Moreover, the measured SIR levels in the patients indicate the need for monitoring between doses to ensure the optimal pharmacotherapy of patients.

Dual Delivery of Cyclosporin A and Etodolac Using Polymeric Nanocapsules in a Rabbit Eye Model: Ocular Biodistribution and Pharmacokinetic Study

Purpose: Commercially available eye drops are loaded only with a single drug. By using the polymeric nanocapsules, dual delivery of 0.05% w/w cyclosporin A (CsA) and 0.2% w/w etodolac (Edc) was achieved. An ultraperformance liquid chromatography/tandem mass spectrometry (UPLC-MS/MS) method was developed for determining simultaneously the biodistribution and pharmacokinetic profile of CsA and Edc in ocular tissues. Methods: After one single drop instillation of nanocapsules into healthy right eyes of rabbits, the eyeballs were enucleated at 5, 15, 30, 60, and 90 min time periods to separate the 5 different ocular tissues. A liquid/liquid extraction method was used for ocular sample extraction using darunavir as internal standard. Using 3 diverse conditions such as bench-top, autosampler, and freeze-thaw, the stability of the analytes at 3 quality control samples in ocular tissues was also checked. Results: Intra- and interday precisions for both CsA and Edc in multiple ocular tissues were <10.32%, and the accuracy was <11.98%. The % bias and % RSD values for CsA and Edc were found within the acceptable limit of ±15%. The highest C_max values were attained in cornea for both the drugs at 60 min postinstillation time point. Despite molecular size and structural differences, both CsA and Edc after liberation from nanocapsule drops can permeate into the tissues of the anterior as well as posterior segments of the eye. Conclusion: The biodistribution and pharmacokinetic data might help and strengthen our understanding of synergetic anti-inflammatory activity of CsA and Edc from nanocapsules after its ocular topical application for managing keratoconjunctivitis sicca.

High-Sensitivity and High-Throughput Quantification of Everolimus in Human Whole Blood Using Ultrahigh-Performance Liquid Chromatography Coupled With Tandem Mass Spectrometry

BACKGROUND

Rigorous dose adjustment by therapeutic drug monitoring (TDM) is recommended when everolimus (EVR) is administered for immunosuppression. In this study, the authors developed a highly sensitive ultrahigh-performance liquid chromatography coupled with the tandem mass spectrometry (UHPLC-MS/MS) method for measuring EVR concentrations in whole blood using a high-throughput solid-phase extraction method for sample pretreatment. Furthermore, the blood EVR concentrations in routine TDM samples from patients who underwent renal transplantation measured using the established UHPLC-MS/MS method were compared with those measured using the latex agglutination turbidimetric immunoassay (LTIA).

METHODS

Blood samples were pretreated by solid-phase extraction using a 96-well HLB µElution plate. The clinical application of the newly developed method was evaluated using 87 blood samples from 19 patients who underwent kidney transplant.

RESULTS

The calibration curve showed good linearity over a wide range of 0.1-50 ng/mL, with relative error ≤15% obtained from the back calculation of calibrators, and ≤20% for the lower limit of quantification. Within-batch and batch-to-batch accuracies and precisions fulfilled the acceptance criteria of the US Food and Drug Administration guidelines for bioanalytical method validation. The extraction recovery rates were good (≥65.2%), and almost no matrix effects were found in any of the quality control samples. Blood EVR concentrations measured by UHPLC-MS/MS were positively correlated with those measured by LTIA. A Bland-Altman plot indicated that the UHPLC-MS/MS method yielded better measurements than the LTIA method, regardless of the concentration.

CONCLUSIONS

Therefore, the authors succeeded in developing a novel high-sensitivity and high-throughput method for measuring blood EVR concentration by UHPLC-MS/MS using a µElution plate for sample pretreatment.