A rapid liquid chromatography-tandem mass spectrometry analysis of whole blood sirolimus using turbulent flow technology for online extraction

Antineoplastic drugs and their analysis: a state of the art review

We provide an overview of the analytical methods available for the quantification of antineoplastic drugs in pharmaceutical formulations, biological and environmental samples.

Current methods of the analysis of immunosuppressive agents in clinical materials: A review

More than 100000 solid organ transplantations are performed every year worldwide. Calcineurin (cyclosporine A, tacrolimus), serine/threonine kinase (sirolimus, everolimus) and inosine monophosphate dehydrogenase inhibitor (mycophenolate mofetil), are the most common drugs used as immunosuppressive agents after solid organ transplantation. Immunosuppressive therapy, although necessary after transplantation, is associated with many adverse consequences, including the formation of secondary metabolites of drugs and the induction of their side effects. Calcineurin inhibitors are associated with nephrotoxicity, cardiotoxicity and neurotoxicity; moreover, they increase the risk of many diseases after transplantation. The review presents a study of the movement of drugs in the body, including the processes of absorption, distribution, localisation in tissues, biotransformation and excretion, and also their accompanying side effects. Therefore, there is a necessity to monitor immunosuppressants, especially because these drugs are characterised by narrow therapeutic ranges. Their incorrect concentrations in a patient's blood could result in transplant rejection or in the accumulation of toxic effects. Immunosuppressive pharmaceuticals are macrolide lactones, peptides, and high molecular weight molecules that can be metabolised to several metabolites. Therefore the two main analytical methods used for their determination are high performance liquid chromatography with various detection methods and immunoassay methods. Despite the rapid development of new analytical methods of analysing immunosuppressive agents, the application of the latest generation of detectors and increasing sensitivity of such methods, there is still a great demand for the development of highly selective, sensitive, specific, rapid and relatively simple methods of immunosuppressive drugs analysis.

A simple and robust LC-MS/MS method for measuring sirolimus and everolimus in whole blood

Therapeutic drug monitoring of immunosuppressants sirolimus and everolimus is mandatory and liquid chromatography tandem mass spectrometry (LC-MS/MS) is the preferred technology for the measurement. Due to the high hydrophobicity these analytes bind to reverse-phase columns tightly and need column heating to elute. Column heating not only requires extra instrument preparation but also causes permanent column damage if the heater is left on while elution pumps stop by the end of the run. The primary improvement in the current method was to elute the analytes at room temperature using special buffers. This new LC-MS/MS method has been validated for clinical use and offers improved simplicity and robustness by eliminating column heating yet with high sensitivity, precision and accuracy.

Low-dose rapamycin (sirolimus) effects in autosomal dominant polycystic kidney disease: an open-label randomized controlled pilot study

BACKGROUND AND OBJECTIVES

The two largest studies of mammalian target of rapamycin inhibitor treatment of autosomal dominant polycystic kidney disease (ADPKD) demonstrated no clear benefit on the primary endpoint of total kidney volume (TKV) or on eGFR. The present study evaluated two levels of rapamycin on the 12-month change in (125)I-iothalamate GFR (iGFR) as the primary endpoint and TKV secondarily.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In a 12-month open-label pilot study, 30 adult patients with ADPKD were randomly assigned to low-dose (LD) rapamycin (rapamycin trough blood level, 2-5 ng/ml) (LD group, n=10), standard-dose (STD) rapamycin trough level (>5-8 ng/ml) (STD group, n=10), or standard care (SC group, n=10). They were evaluated with iGFR and noncontrast computed tomography.

RESULTS

Change in iGFR at 12 months was significantly higher in the LD group (7.7±12.5 ml/min per 1.73 m(2); n=9) than in the SC group (-11.2 ± 9.1 ml/min per 1.73 m(2); n=9) (LD versus SC: P<0.01). Change in iGFR at 12 months in the STD group (1.6 ± 12.1 ml/min per 1.73 m(2); n=8) was not significantly greater than that in the SC group (P=0.07), but it was in the combined treatment groups (LD+STD versus SC: P<0.01). Neither eGFR calculated by the CKD-Epidemiology Collaboration equation nor TKV (secondary endpoint) changed significantly from baseline to 12 months in any of the groups. On the basis of results of the mixed model, during the study, patients in the LD group had significantly lower trough blood levels of rapamycin (mean range ± SD, 2.40 ± 0.64 to 2.90 ± 1.20 ng/ml) compared with those in the STD group (3.93 ± 2.27 to 5.77 ± 1.06 ng/ml) (P<0.01).

CONCLUSION

Patients with ADPKD receiving LD rapamycin demonstrated a significant increase in iGFR compared with those receiving standard care, without a significant effect on TKV after 12 months.

Identification and elimination of ion suppression in the quantitative analysis of sirolimus in human blood by LC/ESI-MS/MS

Ion suppression can negatively affect the performance characteristics of LC/ESI-MS/MS based methods, and we wished to identify sources of ion suppression in an assay for quantitating sirolimus in human whole blood. We first compared the peak areas of sirolimus and ascomycin added to human blood samples treated with and without extraction using octadecyl silyl (ODS)-silica gel after protein precipitation, and we found that water-soluble compounds cause the ion suppression for both drugs. Post-column infusion studies indicated that compounds retained in the sample after ODS extraction and protein precipitation caused ion suppression. MS analysis of these compounds suggested they were hydroxyl group-possessing phosphocholines, and this was confirmed using purified lysophosphatidylcholine variants. Therefore, we included a HybridSPE treatment step after the ODS extraction into the preanalytical workflow to remove phosphocholines, and this successfully eliminated the observed ion suppression for determining sirolimus concentration in human whole blood by LC/ESI-MS/MS. Sirolimus is a highly lipophilic molecule, and this study demonstrates the impact that preanalytical extraction and purification steps can have on a laboratory's ability to accurately detect and quantitate this and other lipophilic drugs.

An accurate quantitative LC/ESI-MS/MS method for sirolimus in human whole blood

Sirolimus is a widely used immunosuppressant that requires therapeutic drug monitoring (TDM). We optimized a preanalytical procedure that allows for the accurate quantiation of sirolimus in whole blood by LC/ESI-MS/MS with minimal matrix effects. Sirolimus is highly lipophilic, and solvents containing greater than 50% methanol were required to maintain sirolimus recovery. The final pretreatment procedure developed consists of a zinc sulfate protein precipitation, an extraction using octadecyl silyl-silica gel for eliminating water-soluble and hydrophilic compounds, and HybridSPE cartridge treatment to eliminate phospholipids. Using this procedure prior to LC/ESI-MS/MS led to the accurate and reproducible quantitation of sirolimus in human whole blood. The linear range of detection was 0.5-50 ng/mL, a range appropriate for TDM, and the method demonstrated good repeatability and intermediate precision within this quantitative range. In order to investigate the quantitative performance of this method, we compared it to two commercially available sirolimus immunoassays and our previously reported LC/ESI-MS/MS method. The immunoassays gave consistently greater values for the sirolimus concentration, and this may be related to antibody cross-reactivity with sirolimus metabolites and/or other matrix effects. Although our procedure is too long to support real-time TDM for outpatients, it can serve as reference method to assess the performance of other analytical methods that are currently available or may be developed in the future.

Correlation of tissue drug concentrations with in vivo magnetic resonance images of polymer drug depot around arteriovenous graft

Sustained delivery of anti-proliferative drugs to the perivascular area using an injectable polymeric platform is a strategy to inhibit vascular hyperplasia and stenosis. In this study, the concentrations of sirolimus in vascular tissues were evaluated after delivery using an injectable platform made of poly(lactic-co-glycolic acid)-polyethylene glycol-poly(lactic-co-glycolic acid) (PLGA-PEG-PLGA). In order to optimize the drug release profile, the effect of two solvents or solid loading of the sirolimus into the polymer gel was first examined in vitro. The early release was slower with loading of dry drug into the polymer, compared to drug dissolution in solvents. Dry sirolimus was therefore used to load the polymer and applied to the perivascular surface of the graft-venous anastomosis at the time of surgical placement of a carotid-jugular synthetic hemodialysis graft in a porcine model. This was replenished by ultrasound-guided injection of additional drug-laden polymer at one, two and three weeks post-operatively. Magnetic resonance imaging (MRI) using pulse sequences specifically designed for optimal detection of the polymeric gel showed that the polymer injected post-operatively remained at the juxta-anastomotic perivascular site at two weeks. Sirolimus was extracted from various segments of the juxta-anastomotic tissues and the drug concentrations were determined using HPLC MS/MS. Tissue sirolimus concentrations at one and two weeks were highest near the venous anastomosis, which were approximately 100- to 500-fold greater than the concentrations necessary to inhibit vascular smooth muscle cell proliferation in vitro. Drug concentrations remained above the inhibitory concentrations for at least six weeks post-operatively. Thus, serial injections of sustained-delivery polymer gel loaded with sirolimus can provide high localized concentrations at target vascular tissues and thus may be useful for the prevention and treatment of vascular proliferative disorders such as hemodialysis graft stenosis. In addition, MRI is useful for the monitoring of the location of the drug depot.

Sensitive quantification of sirolimus and everolimus by LC-MS/MS with online sample cleanup

Sirolimus and its derivative everolimus are widely used today as immunosuppressive agents for example in the transplantation medicine. The problematic pharmacokinetic behavior of those substances makes therapeutic drug monitoring mandatory. Therefore, a fast, simple and sensitive high-throughput procedure using online extraction with turbulent flow chromatography for the concurrent measurement of sirolimus and everolimus has been developed. 200 microl of whole blood was mixed with internal standard (23-desmethoxyrapamycin) and the precipitation solution and centrifuged. An aliquot of the supernatant was transferred into autosampler vials. 50 microl of the supernatant was injected into the LC system, where the analytes were extracted using turbulent flow chromatography and thereafter analyzed using reversed phase chromatography. Detection was done by atmospherical pressure chemical ionization (APCI) mass spectrometry in the negative ionization mode. The method has been fully validated and compared to a previously used method. The method was shown to be linear over the entire calibration range (2.2-43.7 microg/l for everolimus and 2.9-51.2 microg/l for sirolimus). The lower limit of quantification was 0.5 microg/l for both compounds. For within-day and between-day analysis, the CV's were <7.6% for everolimus and <8.7% for sirolimus, respectively. The accuracy was between 92.1% and 105% for everolimus and 96.1% and 106% for sirolimus. Recovery ranged between 46.3% and 50.6% for everolimus and 51.2% and 57.2% for sirolimus. The method was demonstrated to be free of matrix effects and comparable to the previously used method. The presented LC-MS/MS method, using turbulent flow chromatography online extraction, allows a fast, simple and reliable determination of everolimus and sirolimus.