Determination of platinum originating from carboplatin in human urine and canine excretion products by inductively coupled plasma mass spectrometry.

We present highly sensitive, rapid methods for the determination of Pt originating from carboplatin in human urine and canine urine, feces, and oral fluid. The methods are based on the quantification of Pt by inductively coupled plasma mass spectrometry, and allow quantification of 7.50 ng/L Pt in human and canine urine (in 15 µL of matrix), 15.0 ng/L Pt in canine oral fluid (in 15 µL of matrix), and 0.105 ng/g Pt in canine feces (in 5 µg of matrix). Sample pretreatment mainly involved dilution with appropriate diluents. The performance of the methods fulfilled the most recent FDA guidelines for bioanalytical method validation. Validated ranges of quantification were 7.50 to 1.00 × 10(4) ng/L Pt in human and canine urine, 0.105-30.0 ng/g Pt in canine feces, and 15.0 to 1.00 × 10(4) ng/L Pt in canine oral fluid. Canine urine and oral fluid cannot be easily obtained. Therefore, we also investigated the validity of the usage of human matrix samples for the preparation of calibration standards and quality control samples as alternatives, to be used in future clinical studies. The assays are used to support biomonitoring studies and pharmacokinetic studies in pet dogs treated with carboplatin.

Determination of platinum originating from carboplatin in canine sebum and cerumen by inductively coupled plasma mass spectrometry.

We present highly sensitive, reliable methods for the determination of platinum originating from carboplatin in canine sebum and cerumen. The methods are based on the measurement of platinum by inductively coupled plasma mass spectrometry and allow quantification of 0.15 pg platinum per cm² body surface in canine sebum and of 7.50 pg platinum per sampled ear canal. The sample pretreatment procedure involved extraction of wipe samples followed by dilution with appropriate diluents. The performance of the methods, in terms of accuracy and precision, fulfilled the most recent FDA guidelines for bioanalytical method validation. Validated ranges of quantification were 15.0-1.00 x 104 ng L⁻¹ for platinum in canine sebum extraction solution (corresponding to 15.0 pg per wipe sample or 0.15 pgcm⁻²) and 7.50-1.00 x 104 ng L⁻¹ for platinum in canine cerumen extraction solution (corresponding to 7.50 pg per sampled external acoustic meatus). Canine matrices may not always be obtained in sufficient quantities. Therefore, we also confirmed the legitimacy of the application of human matrix samples for the preparation of calibration standards and quality control samples as alternatives, to be used in future clinical studies. The assays are used to support human biomonitoring studies and pharmacokinetic oncology studies in pet dogs treated with carboplatin.

Persistent neuropathy after treatment with cisplatin and oxaliplatin.

BACKGROUND: The aims of the current explorative study were to assess persistent neuropathy in 45 patients up to 6 years after treatment with cisplatin or oxaliplatin and to determine the most adequate method to evaluate neuropathy. Furthermore, the effect of possible determinants on persistent neuropathy was investigated. MATERIAL AND METHODS: The assessment of neuropathy was performed using a questionnaire, by neurological tests, and by vibration threshold (VT) measurements. Because VT determination gives the most objective information, VT measurements were used for further analyses. RESULTS AND DISCUSSION: The analyses revealed that neuropathy of the hands was related to follow-up time, with an observed recovery half-life of 6.8 (+/- 3.1) years. No significant reversibility of neuropathy of the feet within the observation period could be demonstrated. For cisplatin, the severity of neuropathy was related to the cumulative dose and sodium thiosulfate use. Oxaliplatin induced neuropathy did not appear to be related to the dose within the studied dose range. No relationship with platinum levels, renal function, glutathione transferase genotypes, diabetes mellitus, alcohol use, or co-medication could be demonstrated. This study was performed as an explorative study and the issues discussed need to be investigated further.

Long-term platinum retention after treatment with cisplatin and oxaliplatin.

BACKGROUND: The aim of this study was to evaluate long-term platinum retention in patients treated with cisplatin and oxaliplatin. METHODS: 45 patients, treated 8-75 months before participating in this study, were included. Platinum levels in plasma and plasma ultrafiltrate (pUF) were determined. In addition, the reactivity of platinum species in pUF was evaluated. Relationships between platinum retention and possible determinants were evaluated. RESULTS: Platinum plasma concentrations ranged between 142-2.99 x 10(3) ng/L. Up to 24% of plasma platinum was recovered in pUF. No platinum-DNA adducts in peripheral blood mononuclear cells (PBMCs) could be detected. Ex vivo incubation of DNA with pUF of patients revealed that up to 10% of the reactivity of platinum species was retained. Protein binding proceeded during sample storage. Sodium thiosulfate (STS) appeared to release platinum from the plasma proteins. Platinum levels were related to time, dose, STS co-administration, and glomerular filtration rates (GFR). CONCLUSION: Our data suggest that plasma platinum levels are related to time, age, dose, GFR, and STS use. Platinum in plasma, probably, represent platinum eliminated from regenerating tissue. Platinum species in pUF were partly present in a reactive form. The effects of the reactivity on long-term consequences of Pt-containing chemotherapy, however, remains to be established.

The effects of sulfur-containing compounds and gemcitabine on the binding of cisplatin to plasma proteins and DNA determined by inductively coupled plasma mass spectrometry and high performance liquid chromatography-inductively coupled plasma mass spectrometry.

The aim of this study was to investigate the effects of sodium thiosulfate (STS), glutathione (GSH), acetylcysteine (AC), and gemcitabine on the platinum-protein (Pt-protein) and platinum-DNA (Pt-DNA) binding of cisplatin in whole blood. This was done to obtain more insight into the platinum (Pt) binding in whole blood and the effects of modulators on this process. STS, GSH, AC, and gemcitabine were added before and after the incubation of whole blood with cisplatin. Pt levels in plasma and plasma ultrafiltrate and the Pt that is bound to DNA in peripheral blood mononuclear cells were determined using inductively coupled plasma mass spectrometry. Additionally, information on the major Pt-DNA adducts was obtained by separation of the Pt-DNA adducts by high performance liquid chromatography with off-line inductively coupled plasma mass spectrometry detection. Results showed that the reactive Pt levels in whole blood are reduced by STS, GSH, and AC. This reduction was demonstrated by a reduced Pt-protein and Pt-DNA binding in the presence of sulfur compounds. Furthermore, STS and AC seemed to be able to release Pt from proteins. The compounds could hardly release Pt from the DNA. Gemcitabine slightly inhibited Pt-DNA binding and did not alter Pt-protein binding. The type of Pt-DNA adducts found were not altered in the presence of the modulators. In conclusion, the results of this study illustrate that STS, GSH, and AC affect Pt binding in whole blood, which suggests that these compounds could affect Pt binding in patients. By interfering with Pt-DNA and Pt-protein binding, the compounds could influence side effects and cytotoxicity.

The application of inductively coupled plasma mass spectrometry in clinical pharmacological oncology research.

Metal-based anticancer agents are frequently used in the treatment of a wide variety of cancer types. The monitoring of these anticancer agents in biological samples is important to understand their pharmacokinetics, pharmacodynamics, and metabolism. In addition, determination of metals originating from anticancer agents is relevant to assess occupational exposure of health care personnel working with these drugs. The high sensitivity of inductively coupled plasma mass spectrometry (ICP-MS) has resulted in an increased popularity of this technique for the analysis of metal-based anticancer drugs. In addition to the quantitative analysis of the metal of interest in a sample, ICP-MS can be used as an ultrasensitive metal selective detector in combination with speciation techniques such as liquid chromatography. In the current review we provide a systematic survey of publications describing the analysis of platinum- and ruthenium-containing anticancer agents using ICP-MS, focused on the determination of total metal concentrations and on the speciation of metal compounds in biological fluids, DNA- and protein-adducts, and environmental samples. We conclude that ICP-MS is a powerful tool for the quantitative analysis of metal-based anticancer agents from multiple sample sources.

Determination of ruthenium originating from the investigational anti-cancer drug NAMI-A in human plasma ultrafiltrate, plasma, and urine by inductively coupled plasma mass spectrometry.

We present a highly sensitive, rapid method for the determination of ruthenium originating from the investigational anti-cancer drug NAMI-A in human plasma ultrafiltrate, plasma, and urine. The method is based on the quantification of ruthenium by inductively coupled plasma mass spectrometry and allows quantification of 30 ng L(-1) ruthenium in plasma ultrafiltrate and urine, and 75 ng L(-1) ruthenium in human plasma, in 150 microL of matrix. The sample pretreatment procedure is straightforward and only involves dilution with appropriate diluents. The performance of the method, in terms of accuracy and precision, fulfilled the most recent FDA guidelines for bioanalytical method validation. Validated ranges of quantification were 30.0 to 1 x 10(4) ng L(-1) for ruthenium in plasma ultrafiltrate and urine and 75.0 to 1 x 10(4) ng L(-1) for ruthenium in plasma. The applicability of the method and its superiority to atomic-absorption spectrometry were demonstrated in two patients who were treated with intravenous NAMI-A in a phase I trial. The assay is now successfully used to support pharmacokinetic studies in cancer patients treated with NAMI-A.