Determination of 5-fluorouracil in microvolumes of human plasma by solvent extraction and high-performance liquid chromatography

Physical characterization and bioavailability assessment of 5-fluorouracil-based nanostructured lipid carrier (NLC): In vitro drug release, Hemolysis, and permeability modulation

5-Fluorouracil (5-FU) is an anticancer agent belonging to BCS Class III that exhibits poor release characteristics and low retention in the biological system. The main objective of this investigation was to develop a drug delivery system, i.e., Nanostructure Lipid Carriers (NLCs) loaded with 5-FU to prolong its biological retention through 5-FU-loaded NLCs (5-FUNLC) were designed to manipulate physicochemical characteristics and assessment of in vitro and in vivo performance. The developed NLCs underwent comprehensive characterization, including assessments for particle size, zeta potential, morphological evaluation, and FT-IR spectroscopy. Additionally, specific evaluations were conducted for 5-FUNLCs, encompassing analyses for encapsulation efficiency of the drug, release characteristics in PBS at pH 6.8, and stability study. The lipophilic character of 5-FUNLC was confirmed through the measurement of the partition coefficient (log P). 5-FUNLCs were observed as spherical-shaped particles with a mean size of 300 ± 25 nm. The encapsulation efficiency was determined to be 89%, indicating effective drug loading within the NLCs. Furthermore, these NLCs exhibited a sustained release nature lasting up to 3-4 h, indicating their potential for controlled drug release over time. Lipid components were biocompatible with the 5-FU to determine thermal transition temperature and show good stability for 30 days. Additionally, an in vitro hemolysis study that confirmed the system did not cause any destruction to the RBCs during intravenous administration. The drug's gut permeability was assessed utilizing the optimized 5-FUNLC (F2) in comparison to 5-FU through the intestine or gut sac model (in the apical to basolateral direction, A → B). The permeability coefficient was measured as 4.91 × 10-5 cm/h with a significant difference. Additionally, the antioxidant potential of the NLCs was demonstrated through the DPPH method. The NLCs' performance was further assessed through in vivo pharmacokinetic studies on Wistar Rats, resulting in a 1.5-fold enhancement in their activity compared to free 5-FU. These NLCs offer improved drug solubility and sustained release, which collectively contribute to enhanced therapeutic outcomes and modulate bioavailability. The study concludes by highlighting the potential of 5-FUNLC as an innovative and efficient drug delivery system. The findings suggest that further preclinical investigations are warranted, indicating a promising avenue for the development of more effective and well-tolerated treatments for cancer.

Hepatocyte Growth Factor Enhances Antineoplastic Effect of 5-Fluorouracil by Increasing UPP1 Expression in HepG2 Cells

Aberrant activation of hepatocyte growth factor (HGF) and its receptor c-Met axis promotes tumor growth. Therefore, many clinical trials have been conducted. A phase 3 trial investigating a monoclonal antibody targeting HGF in combination with fluoropyrimidine-based chemotherapy had to be terminated prematurely; however, the reason behind the failure remains poorly defined. In this study, we investigated the influence of HGF on the antineoplastic effects of 5-fluorouracil (5-FU), a fluoropyrimidine, in HepG2 cells. HGF suppressed the proliferative activity of cells concomitantly treated with 5-FU more robustly as compared to that of cells treated with 5-FU alone, and markedly increased the expression of uridine phosphorylase 1 (UPP1). Intracellular concentration of 5-fluorouridine, an initial anabolite of 5-FU catalyzed by UPP1, was increased by HGF. Interestingly, erlotinib enhanced HGF-induced increase in UPP1 mRNA; in contrast, gefitinib suppressed it. Furthermore, erlotinib suppressed HGF-increased phosphorylation of the epidermal growth factor receptor at the Tyr1173 site involved in downregulation of extracellular signal-regulated kinase (Erk) activation, and enhanced the HGF-increased phosphorylation of Erk. Collectively, these findings suggest that inhibition of the HGF/c-Met axis diminishes the effects of fluoropyrimidine through downregulation of UPP1 expression. Therefore, extreme caution must be exercised in terms of patient safety while offering chemotherapy comprising fluoropyrimidine concomitantly with inhibitors of the HGF/c-Met axis.

GC Determination of Fluorouracil in Serum by Using Hexafluroroacetylacetone as Derivatizing Reagent

A gas chromatographic (GC) procedure has been developed for the determination of fluorouracil (5-FU) after pre-column derivatization with hexafluoroacetylacetone. GC separation was from column DB-1 (30 m × 0.32 mm id) and the determination was by flame-ionization detection. The derivatization conditions were optimized at pH 4, heating at 90°C for 40 min and extraction of the derivative was in chloroform. Using the conditions nucleobases cytosine, uracil, thymine, adenine and guanine separated completely from fluorouracil. The linear calibration range and LOD for 5-fluorouracil were 0.5-40.0 and 0.2 μg/mL, respectively. The derivatization, elution and separation were repeatable in terms of retention time and peak height/peak area (n = 5) and relative standard deviations (RSD) were within 3.5%. The method was applied for the analysis of serum spiked with 5-FU with recovery of 95.5-97.5% with RSD 1.5-3.1%.

Wirelessly Controlled Implantable System for On-demand and Pulsatile Insulin Administration

We propose a wirelessly controlled implantable system for on-demand and pulsatile insulin delivery with a more convenient and safer strategy than currently available strategies. The system is a combined entity of a magnetically driven pump (i.e., an MDP), external control device (i.e., an ECD) and mobile app. The MDP for implantation consists of a plunger, barrel and drug reservoir, where an accurate amount of insulin can be infused in a pulsatile manner only at the time when a magnetic force is applied to actuate the plunger in the barrel. The ECD at the outside body can modulate the MDP actuation with an electromagnet and its control circuit, and this modulation can be wirelessly controlled by the mobile app. As a safety feature, the mobile app is programmed to pre-set the restrictions for the insulin dose and administration schedule to avoid overdose. The system is shown to infuse insulin in a highly reproducible manner, but it does not allow for insulin infusion when the pre-set restrictions are violated. When tested with diabetic rats, the profiles of insulin plasma concentration and blood glucose level are similar to those of animals treated with a subcutaneous injection of the same dose of insulin.

Pharmacokinetic application of a bio-analytical LC-MS method developed for 5-fluorouracil and methotrexate in mouse plasma, brain and urine

In the past we have reported significant cognitive deficits in mice receiving 5-fluorouracil in combination with low-dose methotrexate. To explain such interactions, a pharmacokinetic study was designed. A sensitive bio-analytical method was therefore developed and validated for 5-fluorouracil and methotrexate in mouse plasma, brain and urine with liquid chromatography coupled to a single quadrupole mass spectrometer. Chromatographic separation was accomplished by Agilent® Zorbax® SB-C18 column, with isocratic elution (5 mM ammonium acetate and methanol, 70:30, %v/v) at a flow rate of 300 μL/min. The limit of quantitation for both drugs was 15.6 ng/mL (plasma and brain) and 78.1 ng/mL (urine), with interday and intraday precision and accuracy ≤15% and a total run time of 6 min. This bio-analytical method was used for the pharmacokinetic characterization of 5-fluorouracil and methotrexate in mouse plasma, brain and urine over a period of 24 h. This method allowed characterization of the brain concentrations of 5-fluorouracil over a period of 24 h.

Development and validation of a rapid and sensitive HPLC method for the quantification of 5-fluorocytosine and its metabolites

To study the intracellular metabolism of the prodrug 5-fluorocytosine (5FC), we developed a novel reverse-phase high-performance liquid chromatography method to simultaneously detect 5FC and its four major anabolic metabolites: 5-fluorouracil, 5-fluorouridine, 5-fluorouridine-monophosphate and 5-fluoro-2'deoxyuridine-5'-monophosphate. Separation of each compound was accomplished under isocratic conditions using a C(18) column and mobile phase of formic acid-water (1 : 99 v/v). The method was validated for both accuracy and reproducibility in cell culture media. Additionally, metabolites were assessed for stability at ambient temperatures and following freeze-thaw cycles. Calibration curves were linear over a range of 1-200 microg/mL. Limit of quantification for four of the five compounds was 1 microg/mL in cell culture media (RSD < 11%). This method was successfully used to monitor intracellular conversion of 5FC to its metabolic products over a 24h period.

A review of analytical methods for the determination of 5-fluorouracil in biological matrices

5-Fluorouracil (5-FU) is a cytostatic agent that has been widely used in the treatment of various solid tumours for more than 20 years, and is still considered to be among the most active antineoplastic agents in advanced colorectal cancer and malignancies of the head and neck. A large number of non-chromatographic and chromatographic methods for the quantitation of 5-FU, related prodrugs and their metabolites in biological matrices have been developed in the last 30 years to support preclinical and clinical studies. However, 5-FU monitoring has not been widely used, at least not in the USA, and certainly not outside the clinical research setting, given the absence of simple, fast and inexpensive testing methods for 5-FU monitoring. Recent developments with testing based on liquid chromatography-tandem mass spectrometry and a nanoparticle antibody-based immunoassay may facilitate routine monitoring of 5-FU in daily clinical practice. In this review the advantages and disadvantages of the bioanalytical methods developed and used for 5-FU, its metabolites and related prodrugs are discussed.

Pharmacokinetics of 5-fluorouracil in mutant Nagase analbuminemic rats: faster metabolism of 5-fluorouracil via CYP1A

It has been reported that plasma albumin concentrations were significantly lower in cancer patients than those in the healthy volunteers, and the expression and mRNA level of hepatic microsomal cytochrome P450 (CYP) 1A2 increased in mutant Nagase analbuminemic rats (NARs). After intravenous administration of 5-fluorouracil at a dose of 30 mg/kg to NARs, the time-averaged nonrenal clearance (Clnr) of the drug was significantly faster than the controls (51.3 versus 28.8 ml/min/kg), possibly due to an increase in the expression and mRNA level of CYP1A2 in NARs. In order to determine whether 5-fluorouracil is metabolized via CYP1A2 in male Sprague-Dawley rats, the rats were pretreated with 3-methylcholanthrene (a main inducer of CYP1A1/2 in rats). The Clnr of 5-fluorouracil was significantly faster (34.3 versus 27.3 ml/min/kg) in rats pretreated with 3-methylcholanthrene. The aforementioned data indicate that CYP1A is involved in the metabolism of 5-fluorouracil in rats.

A pharmacokinetic interaction study of docetaxel and cisplatin plus or minus 5-fluorouracil in the treatment of patients with recurrent or metastatic solid tumors

BACKGROUND

The purpose of this study was to look at the pharmacokinetics of docetaxel, cisplatin-derived platinum and 5-fluorouracil (5-FU), when used in combination, to exclude potential clinically relevant pharmacokinetic interactions.

METHODS

Fifteen patients with recurrent or metastatic solid tumors were randomized to receive docetaxel 75 mg/m2 and cisplatin 75 mg/m2 in the first treatment course on day 1 and the same combination plus 5-FU 750 mg/m2/day on days 1-5 in the second course, or the two treatment courses in reversed order. Cycles were repeated every 3 weeks. A pharmacokinetic analysis was performed during the first two cycles.

RESULTS

Full pharmacokinetic data was available for 12 of the 15 patients. Treatment was tolerated well, with frequency of toxicity consistent with the safety profile known for docetaxel, cisplatin and 5-FU. Mean clearance values for docetaxel and cisplatin showed no statistically significant difference across the "triple" and the "double" combination treatments, and the mean pharmacokinetic parameters of all agents were within the ranges for previously reported single agent treatment.

CONCLUSION

No clinically relevant pharmacokinetic interactions between docetaxel, cisplatin and 5-FU used in combination were noticed in this study.

A Simple and Sensitive Fully Validated HPLC-UV Method for the Determination of 5-Fluorouracil and Its Metabolite 5,6-Dihydrofluorouracil in Plasma

The authors developed a simple and sensitive, fully validated HPLC-UV method for the determination of both 5-FU and its metabolite DHFU in small-volume plasma samples. The analytes were separated on a 4.6 x 250 mm ID Atlantis dC18 5-microm column with isocratic elution at room temperature. Chlorouracil was used as internal standard. The analytes were detected with an UV diode array detector. DHFU was detected at 205 nm, 5-FU at 266 nm, and chlorouracil at both wavelengths. The limits of quantification in plasma were 0.040 mug /mL for 5-FU and 0.075 microg/mL for DHFU. Linearity, accuracy, precision, recovery, dilution, freeze-thaw stability, and stability in the sample compartment were evaluated. The method appeared linear over a range from 0.04 to 15.90 microg/mL for 5-FU and from 0.075 to 3.84 microg/mL for DHFU. The method appeared very suitable for therapeutic drug monitoring and pharmacokinetic studies of 5-FU because of its simple extraction and small sample volume. Problems in earlier published methods with interfering peaks and variable retention times were overcome. The method appeared also to be suitable for detection of uracil and its metabolite dihydrouracil in plasma.

Pharmacokinetics of 5-fluorouracil in rats with diabetes mellitus induced by streptozotocin

The pharmacokinetic parameters of 5-fluorouracil were compared after intravenous administration at a dose of 30 mg/kg to control Sprague-Dawley rats and to rats with diabetes mellitus induced by streptozotocin (DMIS). In DMIS rats, the area under the plasma concentration-time curve from time zero to time infinity (AUC) was significantly smaller (603 versus 909 microg min/ml) due to the significantly faster total body clearance (Cl; 47.8 versus 33.0 ml/min/kg). The faster Cl was due to the significantly faster renal (8.54 versus 4.02 ml/min/kg) and nonrenal (38.5 versus 28.7 ml/min/kg) clearances. In DMIS rats, the total amount of unchanged 5-fluorouracil excreted in 24 h urine was significantly greater (34.1% versus 13.0% of intravenous dose) due to the urine flow rate-dependent renal clearance of 5-fluorouracil in rats (the greater the urine flow rate, the greater the urinary excretion of 5-fluorouracil). Greater urinary excretion and a significantly smaller AUC resulted in a significantly faster Cl(r) in DMIS rats. The faster Cl(nr) in DMIS rats could be due to an increase in the expression and mRNA level of CYP1A1/2 in the rats.

Rapid determination of 5-fluorouracil in plasma using capillary electrophoresis

A rapid, simple and sensitive capillary electrophoresis (CE) method used for the determination of 5-fluorouracil in rabbit plasma is described in the present paper. In this method, samples were simply pretreated by a solvent extraction procedure prior to injection. With a running buffer composed of 30 mM Tris-H(3)PO(4) (pH 7.0) and 5% isopropanol, 5-fluorouracil was easily separated from the external standard alpha-phenethylol as well as other substances existed in the plasma. A linearity of 5-fluorouracil was determined in the range from 0.17 to 42.50 microg/ml with a correlation coefficient of 0.999. A limit of quantitation (LOQ) corresponding to signal-to-noise ratio of 10 was obtained (LOQ=0.08 microg/ml). The method was successfully used for determining the 5-fluorouracil in real plasma samples from rabbits.