Spectrofluorimetric determination of irinotecan in the presence of oxidant agents and metal ions

In this work four spectrofluorimetric methods for the determination of irinotecan (CPT-11) in human urine and pharmaceuticals have been developed. Initially, the fluorescent characteristics of irinotecan (CPT-11) have been studied in both acidic and basic media. Later, the fluorescence emission generated by the oxidation of CPT-11 with several agents was studied. A quenching of fluorescence could be observed in the presence of Ce(IV) and I₂/I⁻. Also, the reaction between several divalent and trivalent metal ions with CPT-11 was studied, and one method in presence of Fe³⁺ was developed since it was the only metal ion that changes the fluorescence of the analyte. The proposed methods present limit of detection comprises between 0.46 and 2.57 ng mL⁻¹. The spectrofluorimetric methods were applied to human urine. No pre-treatment of the sample was necessary, only a dilution 1:20 with water was made. No interference of the matrix was observed in the conditions used. Recoveries were comprises between 100.0 and 104.3%. Also, pharmaceuticals preparations were analyzed with recoveries between 106.7 and 119.7%. The proposed spectrofluorimetric methods were validated by RP-HPLC, obtaining that the oxidation with iodine is the best method to analyze urine samples, while than, the fluorimetric method developed at acidic pH value is the best for the analysis of pharmaceuticals.     

A theoretical study on camptothecin–AM1 treatment

Camptothecin (irinotecan), a new cytotoxic agent having antitumor activity and especially used in the treatment of advanced colorectal cancers is considered for AM1–RHF type semiempirical quantum chemical treatment together with some analogs of camptothecin. The structural properties and energetics of these molecules have been compared. The structures arising from monoprotonation of camptothecin at various sites are analyzed from thermodynamic point of view.     

High resolution electrospray ionization ion mobility spectrometry

Current commercially available ion mobility spectrometers are intended for the analysis of chemicals in the gas phase. Sample introduction methods, such as direct air sampling, a GC injector or a thermal desorber, are commonly an integral part of these instruments. This paper describes an electrospray ionization ion mobility spectrometer system that allows direct introduction samples in solution phase. This allows direct analysis of non-volatile organic and biological samples, and avoids decomposition of thermally liable samples, providing reliable chemical identification. In addition, the new ion mobility spectrometer allows mobility analysis with high resolving power. Commonly used commercial IMS systems provide resolving powers between 10 and 30; this new ion mobility spectrometer has resolving power greater than 60 for routine analysis. A high resolution instrument is necessary for many applications where a complex mixture needs to be separated and quantified. This paper demonstrates the advantages of using a high resolution ion mobility spectrometer and an electrospray ionization source for the analysis of non-volatile pharmaceuticals as well as dissolved explosive in solution phase.     

Highly sensitive fluorescence quantification of irinotecan in biological fluids with the aid of second-order advantage

<正>A rapid,green and highly sensitive excitation-emission matrix(EEM) fluorescence method was proposed for analysis of irinotecan(CPT-11) in biological fluids including human plasma and urine samples of uncalibrated interferences with the aid of second-order advantage.Due to the serious spectral overlapping from biological matrices,the parallel factor analysis(PARAFAC) and the alternating normalization-weighted error(ANWE) have been recommended to perform directly calibration and overcome the problem which makes the traditional fluorospectrophotometer in trouble.Satisfactory results can be achieved.Furthermore, performance of the proposed method was evaluated based on figures of merit and some statistical parameters.The accuracy of both algorithms was validated by the elliptical joint confidence region(EJCR) test.The precision and repeatability were also investigated by the relative standard deviations(RSDs) of intra-day and inter-day.     

Determination of anticarcinogenic and rescue therapy drugs in urine by photoinduced spectrofluorimetry using multivariate calibration: comparison of several second-order methods

This paper shows the potential of excitation–emission fluorescence spectroscopy and several second-order methods, such as parallel factor analysis (PARAFAC), multiway partial least-squares (N-PLS) or bilinear least-squares (BLLS), as a multicalibration technique for the analysis of leucovorin (LV) and irinotecan (CPT-11). Although CPT-11 presents native fluorescence, leucovorin has little native fluorescence; however, under irradiation with short-wavelength UV light in the presence of traces of hydrogen peroxide, leucovorin was converted into a highly fluorescent compound. This reaction has been used for the sensitive and selective determination of both compounds. The convenience of analysing the total luminescence spectrum information when using multivariate calibration methods on fluorescence data is demonstrated. Direct determination of mixtures of both drugs in urine was accomplished on the basis of excitation–emission matrices (EEMs) and the three-way multivariate methods.     

Room-temperature phosphorimetry for the determination of trace contaminations of camptothecin in anticancer drugs

Campthotecin derivatives, irinotecan (CPT-11) and topotecan (TPT), have been used for the treatment of cancer and camptothecin (CPT) is a potential contaminant in these anticancer medicines. In this work, room-temperature phosphorimetry was used to quantify either CPT as trace contaminants in anticancer drugs and CPT-11 as the main ingredient in anticancer medicines. Phosphorescence from CPT-11 was induced using Pb(NO₃)₂ in SDS treated cellulose substrate while CPT was selectively detected using TlNO₃ as a phosphorescence enhancer in either cellulose or nylon substrates. The limit of quantification for CPT and CPT-11 was in ng order. A detailed metrological study was made to calculate the combined uncertainty associated to the CPT phosphorescence measurement. Satisfactory analyte recoveries were obtained for CPT-11 as a main active ingredient of a pharmaceutical formulation. The selective determination of CPT in a matrix containing TPT was made using the higher order (2nd) derivative of the excitation spectra. The results demonstrated the applicability of the method due its simplicity, cost effectiveness and selectivity.     

Electrochemical Study on the Interaction of Irinotecan with Calf Thymus Double Stranded DNA

Voltammetric behavior of Irinotecan (CPT‐11) was studied in a phosphate buffer (0.002 mol·L^?1, pH 7.5) solution at the hanging mercury drop electrode (HMDE) using cyclic voltammetry (CV). CPT‐11 showed two irreversible cathodic peaks at ?1.01 V and ?1.09 V which involved two electrons and two protons in each reduction step. In addition, the interaction of Irinotecan with double‐stranded calf thymus DNA (ds‐DNA) was studied by CV at the HMDE employing an irreversible electrochemical equation. As a result of the reaction with ds‐DNA, the reduction peaks related to CPT‐11 were shifted in a negative direction and the peak currents were decreased. The diffusion coefficients of CPT‐11 in the absence (D_f) and presence (D_b) of ds‐DNA were calculated as 2.8×10^?5 cm²·s^?1 and 1.6×10^?5 cm²·s^?1 respectively. The binding constant (K=1.0×10⁴ L·mol^?1), and binding site size (s=0.60) of CPT‐11 interacting with ds‐DNA were obtained simultaneously by non‐linear fit analysis. The results demonstrate that the main interaction mode of CPT‐11 with ds‐DNA is electrostatic.     

Accurate determination of the anticancer prodrug simmitecan and its active metabolite chimmitecan in various plasma samples based on immediate deactivation of blood carboxylesterases

Simmitecan (L-P) is an anticancer ester prodrug, which involves activation to chimmitecan (L-2-Z). In the current study, a liquid chromatography/tandem mass spectrometry-based method was developed for simultaneous determination of L-P and L-2-Z in various plasma samples. Because L-P is rapidly converted to L-2-Z by blood carboxylesterase during and after sampling, which hampers accurate determination of L-P and L-2-Z in the biological samples, different carboxylesterase inhibitors were tested. As a result, bis(4-nitrophenyl)phosphate gave the best results with respect to inhibitory capability, hemolysis, and matrix effects and was used to deactivate blood carboxylesterases when sampling. The plasma samples were precipitated with acetonitrile and the resulting supernatants were separated using a pulse gradient method on a C18 column. Irinotecan and camptothecin were used as internal standards for quantification of L-P and L-2-Z, respectively. Protonated L-P, L-2-Z and their internal standards were generated by electrospray ionization and their precursor-product ion pairs (m/z 599→124, 405→361, 587→195, and 349→305, respectively) were used for measurement. The newly developed bioanalytical assay processed favorable accuracy and precision with lower limits of quantification of 2.1 nM for L-P and 3.4 nM for L-2-Z, and was successfully applied to pharmacokinetic studies in tumor-bearing nude mice, rats, and dogs. There are substantial species differences in the ester activity. The experimental strategies illustrated in our report may be adopted for measurement of other prodrugs (including irinotecan) or drugs subject to ester hydrolysis, as well as their metabolites, in biological matrices.     

Versatile online SPE–HPLC method for the analysis of Irinotecan and its clinically relevant metabolites in biomaterials

Monitoring levels of Irinotecan and its metabolites during cancer therapy could help link broad interpatient variations in antitumor activity and toxicity to the patient's metabolic status. We have developed and validated a versatile and highly sensitive method for the simultaneous determination of Irinotecan and its clinically relevant metabolites 7‐ethyl‐10‐hydroxy‐camptothecin (SN‐38) and SN‐38 glucuronide. Sample clean‐up involves precipitation by acetone/methanol/0.5 M trichloroacetic acid at 4:4:2 v/v followed by extraction of the metabolites on an SPE column by 20% methanol in 25 mM KH₂PO₄ pH 2.9. Online transfer to an analytical μBondapak C18 column, elution with 24% acetonitrile (ACN) in 0.1 M KH₂PO₄ pH 2.9 and fluorescence detection with excitation at 375 nm and emission at 430 nm for SN‐38 glucuronide and Irinotecan or 540 nm for SN‐38 results in high sensitivity (1–2 pg) and short (～10 min) run times. The method was used to determine the degree of SN‐38 glucuronidation in mice after Irinotecan administration and in cultured cancer cells exposed to SN‐38. The method may be used to better understand Irinotecan metabolism, personalize therapy, and develop Irinotecan‐based tumor targeting therapies.