The achievement of mass balance by simultaneous quantification of floxuridine prodrug, floxuridine, 5-fluorouracil, 5-dihydrouracil, α-fluoro-β-ureidopropionate, α-fluoro-β-alanine using LC-MS

Systemic exposure of floxuridine after hepatic arterial infusion pump chemotherapy with floxuridine in patients with resected colorectal liver metastases

BACKGROUND

Floxuridine's high hepatic extraction ratio and short elimination half-life allows maximum liver exposure with minimal systemic side-effects. This study attempts to quantify the systemic exposure of floxuridine.

METHODS

Patients undergoing continuous hepatic arterial infusion pump (HAIP) floxuridine after resection of colorectal liver metastases (CRLM) in two centres underwent six cycles of floxuridine at start dose 0.12 mg/kg/day. No concomitant systemic chemotherapy was administered. Peripheral venous blood samples were drawn during the first two cycles: pre-dose (only in the second cycle), 30 min, 1 h, 2 h, 7 h, and 15 days after floxuridine infusion. Foxuridine concentration in the residual pump reservoir was measured on day 15 of both cycles. A floxuridine assay with a lower boundary of detection of 0.250 ng/mL was developed.

RESULTS

265 blood samples were collected in the 25 patient included in this study. Floxuridine was mostly measurable at day 7 and day 15 (86 % and 88 % of patients respectively). The median dose corrected concentrations were 0.607 ng/mL [IQR: 0.472-0.747] for cycle 1 day 7, 0.579 ng/mL [IQR: 0.470-0.693] for cycle 1 day 15, 0.646 ng/mL [IQR: 0.463-0.8546] for cycle 2 day 7, and 0.534 ng/mL [IQR: 0.4257-0.7075] for cycle 2 day 15. One patient had remarkably high floxuridine concentrations reaching up to 44 ng/mL during the second cycle, without a clear explanation. The floxuridine concentration in the pump decreased by 14.7 % (range 0.5 %-37.8 %) over a period of 15 days (n = 18).

CONCLUSION

Overall, negligible systemic concentrations of floxuridine were detected. However, remarkably increased levels were detected in one patient. Floxuridine concentration in the pump decreases over time.

Study of intracellular anabolism of 5-fluorouracil and incorporation in nucleic acids based on an LC-HRMS method

5-Fluorouracil (5-FU) is an anticancer drug extensively used for different cancers. Intracellular metabolic activation leads to several nucleoside and nucleotide metabolites essential to exert its cytotoxic activity on multiple cellular targets such as enzymes, DNA and RNA. In this paper, we describe the development of a method based on liquid chromatography coupled with high resolution mass spectrometry suitable for the simultaneous determination of the ten anabolic metabolites (nucleoside, nucleotide and sugar nucleotide) of 5-FU. The chromatographic separation was optimized on a porous graphitic carbon column allowing the analysis of the metabolites of 5-FU as well as endogenous nucleotides. The detection was performed on an Orbitrap® tandem mass spectrometer. Linearity of the method was verified in intracellular content and in RNA extracts. The limit of detection was equal to 12 pg injected on column for nucleoside metabolites of 5-FU and 150 pg injected on column for mono- and tri-phosphate nucleotide metabolites. Matrix effect was evaluated in cellular contents, DNA and RNA extracts for nucleoside and nucleotides metabolites. The method was successfully applied to i) measure the proportion of each anabolic metabolite of 5-FU in cellular contents, ii) follow the consequence of inhibition of enzymes on the endogenous nucleotide pools, iii) study the incorporation of metabolites of 5-FU into RNA and DNA, and iv) to determine the incorporation rate of 5-FUrd into 18 S and 28 S sub-units of rRNA.

•

The LC-MS-HRMS method allows the analysis of the ten anabolic metabolites of 5-FU.

•

The present method is useful to study the incorporation of 5-FU into RNA and DNA.

•

Method to determine the incorporation rate of 5-FU into subunit of rRNA is innovative.

A Critical Review on Clinical Application of Separation Techniques for Selective Recognition of Uracil and 5-Fluorouracil

The most important objectives that are frequently found in bio-analytical chemistry involve applying tools to relevant medical/biological problems and refining these applications. Developing a reliable sample preparation step, for the medical and biological fields is another primary objective in analytical chemistry, in order to extract and isolate the analytes of interest from complex biological matrices. Since, main inborn errors of metabolism (IEM) diagnosable through uracil analysis and the therapeutic monitoring of toxic 5-fluoruracil (an important anti-cancerous drug) in dihydropyrimidine dehydrogenase deficient patients, require an ultra-sensitive, reproducible, selective, and accurate analytical techniques for their measurements. Therefore, keeping in view, the diagnostic value of uracil and 5-fluoruracil measurements, this article refines several analytical techniques involved in selective recognition and quantification of uracil and 5-fluoruracil from biological and pharmaceutical samples. The prospective study revealed that implementation of molecularly imprinted polymer as a solid-phase material for sample preparation and preconcentration of uracil and 5-fluoruracil had proven to be effective as it could obviates problems related to tedious separation techniques, owing to protein binding and drastic interferences, from the complex matrices in real samples such as blood plasma, serum samples.

The dipeptide monoester prodrugs of floxuridine and gemcitabine-feasibility of orally administrable nucleoside analogs

Dipeptide monoester prodrugs of floxuridine and gemcitabine were synthesized. Their chemical stability in buffers, enzymatic stability in cell homogenates, permeability in mouse intestinal membrane along with drug concentration in mouse plasma, and anti-proliferative activity in cancer cells were determined and compared to their parent drugs. Floxuridine prodrug was more enzymatically stable than floxuridine and the degradation from prodrug to parent drug works as the rate-limiting step. On the other hand, gemcitabine prodrug was less enzymatically stable than gemcitabine. Those dipeptide monoester prodrugs exhibited 2.4- to 48.7-fold higher uptake than their parent drugs in Caco-2, Panc-1, and AsPC-1 cells. Floxuridine and gemcitabine prodrugs showed superior permeability in mouse jejunum to their parent drugs and exhibited the higher drug concentration in plasma after in situ mouse perfusion. Cell proliferation assays in ductal pancreatic cancer cells, AsPC-1 and Panc-1, indicated that dipeptide prodrugs of floxuridine and gemcitabine were more potent than their parent drugs. The enhanced potency of nucleoside analogs was attributed to their improved membrane permeability. The prodrug forms of 5′-l-phenylalanyl-l-tyrosyl-floxuridine and 5′-l-phenylalanyl-l-tyrosyl-gemcitabine appeared in mouse plasma after the permeation of intestinal membrane and the first-pass effect, suggesting their potential for the development of oral dosage form for anti-cancer agents.

The development of orally administrable gemcitabine prodrugs with D-enantiomer amino acids: enhanced membrane permeability and enzymatic stability

Gemcitabine prodrugs with D- and L-configuration amino acids were synthesized and their chemical stability in buffers, resistance to glycosidic bond metabolism, enzymatic activation, permeability in Caco-2 cells and mouse intestinal membrane, anti-proliferation activity in cancer cell were determined and compared to that of parent drug, gemcitabine. Prodrugs containing D-configuration amino acids were enzymatically more stable than ones with L-configuration amino acids. The activation of all gemcitabine prodrugs was 1.3-17.6-fold faster in cancer cell homogenate than their hydrolysis in buffer, suggesting enzymatic action. The enzymatic activation of amino acid monoester prodrugs containing D-configuration amino acids in cell homogenates was 2.2-10.9-fold slower than one of amino acid monoester prodrugs with L-configuration amino acids. All prodrugs exhibited enhanced resistance to glycosidic bond metabolism by thymidine phosphorylase compared to parent gemcitabine. Gemcitabine prodrugs showed superior the effective permeability in mouse jejunum to gemcitabine. More importantly, the high plasma concentration of d-amino acid gemcitabine prodrugs was observed more than one of L-amino acid gemcitabine prodrugs. In general, the 5'-mono-amino acid monoester gemcitabine prodrugs exhibited higher permeability and uptake than their parent drug, gemcitabine. Cell proliferation assays in AsPC-1 pancreatic ductal cell line indicated that gemcitabine prodrugs were more potent than their parent drug, gemcitabine. The transport and enzymatic profiles of 5'-D-valyl-gemcitabine and 5'-D-phenylalanyl-gemcitabine suggest their potential for increased oral uptake and delayed enzymatic bioconversion as well as enhanced uptake and cytotoxic activity in cancer cells, would facilitate the development of oral dosage form for anti-cancer agents and, hence, improve the quality of life for the cancer patients.

Selection of suitable prodrug candidates for in vivo studies via in vitro studies; the correlation of prodrug stability in between cell culture homogenates and human tissue homogenates

PURPOSE

To determine the correlations/discrepancies of drug stabilities between in the homogenates of human culture cells and of human tissues.

METHODS

Amino acid/dipeptide monoester prodrugs of floxuridine were chosen as the model drugs. The stabilities (half-lives) of floxuridine prodrugs in human tissues (pancreas, liver, and small intestine) homogenates were obtained and compared with ones in cell culture homogenates (AcPC-1, Capan-2, and Caco-2 cells) as well as human liver microsomes. The correlations of prodrug stability in human small bowel tissue homogenate vs. Caco-2 cell homogenate, human liver tissue homogenate vs. human liver microsomes, and human pancreatic tissue homogenate vs. pancreatic cell, AsPC-1 and Capan-2, homogenates were examined.

RESULTS

The stabilities of floxuridine prodrugs in human small bowel homogenate exhibited the great correlation to ones in Caco-2 cell homogenate (slope = 1.0-1.3, r2 = 0.79-0.98). The stability of those prodrugs in human pancreas tissue homogenate also exhibited the good correlations to ones in AsPC-1 and Capan-2 cells homogenates (slope = 0.5-0.8, r2 = 0.58-0.79). However, the correlations of prodrug stabilities between in human liver tissue homogenates and in human liver microsomes were weaker than others (slope = 1.3-1.9, r2 = 0.07-0.24).

CONCLUSIONS

The correlations of drug stabilities in cultured cell homogenates and in human tissue homogenates were compared. Those results exhibited wide range of correlations between in cell homogenate and in human tissue homogenate (r2 = 0.07 - 0.98). Those in vitro studies in cell homogenates would be good tools to predict drug stabilities in vivo and to select drug candidates for further developments. In the series of experiments, 5'-O-D-valyl-floxuridine and 5'-O-L-phenylalanyl-L-tyrosyl-floxuridine would be selected as candidates of oral drug targeting delivery for cancer chemotherapy due to their relatively good stabilities compared to other tested prodrugs.

Chemical derivatization as a tool for optimizing MS response in sensitive LC–MS/MS bioanalysis and its role in pharmacokinetic studies

Chemical derivatization is the only technique that directly affects the physicochemical property of an analyte in an LC–MS/MS assay platform. On the other side, current MS instruments are extremely sensitive, but still their absolute sensitivity is analyte-dependent. In this review, first, difficulty in analyzing neutral compounds and introducing acidity/basicity and/or proton affinity will be described. Second, the sweet spot of the conventional MS ion source across clogP values is presented. Third, optimization of hydrophilicity/hydrophobicity by derivatization is described. Lastly, development of a new derivatizing reagent specifically designed for LC–MS/MS is described and its significance in pharmacokinetic analysis is discussed.