Identification and quantification of metabolite conjugates of activated cyclophosphamide and ifosfamide with mesna in urine by ion-pair extraction and fast atom bombardment mass spectrometry

Mesna Improves Outcomes of Sulfur Mustard Inhalation Toxicity in an Acute Rat Model

Inhalation of high levels of sulfur mustard (SM), a potent vesicating and alkylating agent used in chemical warfare, results in acutely lethal pulmonary damage. Sodium 2-mercaptoethane sulfonate (mesna) is an organosulfur compound that is currently Food and Drug Administration (FDA)-approved for decreasing the toxicity of mustard-derived chemotherapeutic alkylating agents like ifosfamide and cyclophosphamide. The nucleophilic thiol of mesna is a suitable reactant for the neutralization of the electrophilic group of toxic mustard intermediates. In a rat model of SM inhalation, treatment with mesna (three doses: 300 mg/kg intraperitoneally 20 minutes, 4 hours, and 8 hours postexposure) afforded 74% survival at 48 hours, compared with 0% survival at less than 17 hours in the untreated and vehicle-treated control groups. Protection from cardiopulmonary failure by mesna was demonstrated by improved peripheral oxygen saturation and increased heart rate through 48 hours. Additionally, mesna normalized arterial pH and pACO2 Airway fibrin cast formation was decreased by more than 66% in the mesna-treated group at 9 hour after exposure compared with the vehicle group. Finally, analysis of mixtures of a mustard agent and mesna by a 5,5'-dithiobis(2-nitrobenzoic acid) assay and high performance liquid chromatography tandem mass spectrometry demonstrate a direct reaction between the compounds. This study provides evidence that mesna is an efficacious, inexpensive, FDA-approved candidate antidote for SM exposure. SIGNIFICANCE STATEMENT: Despite the use of sulfur mustard (SM) as a chemical weapon for over 100 years, an ideal drug candidate for treatment after real-world exposure situations has not yet been identified. Utilizing a uniformly lethal animal model, the results of the present study demonstrate that sodium 2-mercaptoethane sulfonate is a promising candidate for repurposing as an antidote, decreasing airway obstruction and improving pulmonary gas exchange, tissue oxygen delivery, and survival following high level SM inhalation exposure, and warrants further consideration.

Pharmacologic Treatment of Noninfectious Uveitis

Uveitis encompasses a spectrum of diseases whose common feature is intraocular inflammation, which may be infectious or noninfectious in etiology (Nussenblatt and Whitcup 2010). Infectious causes of uveitis are typically treated with appropriate antimicrobial therapy and will not be discussed in this chapter. Noninfectious uveitides are thought have an autoimmune component to their etiology and are thus treated with anti-inflammatory agents.

Impaired liver regeneration following partial hepatectomy using the Pringle maneuver: Protective effect of mesna

BACKGROUND AND AIM

We investigated the role of the prophylactic administration of the antioxidant 2-mercaptoethane sulfonate (mesna) on the hepatocyte-regenerating capacity following partial hepatectomy (PH) with concurrent Pringle maneuver.

METHODS

Wistar rats were subjected to PH (70% hepatectomy), 30 min Pringle maneuver, PH plus Pringle with or without mesna pretreatment (400 mg/kg, per os, 3 h before Pringle), or sham operation. At 24 h, 48 h, 72 h, and 1 week after operation, relative liver weight, hepatocyte mitotic activity (mitotic index), the histopathological score and serum aspartate aminotransferase, and alanine aminotransferase concentrations were assessed. At 1 h after operation, oxidative stress markers (glutathione to glutathione disulfide ratio, malondialdehyde concentration, and superoxide dismutase activity) and nuclear factor-kappaB (NF-kappaB) activity were assessed.

RESULTS

Hepatectomy stimulated the regenerating process and induced mild oxidative stress and the activation of NF-kappaB in hepatocytes, while causing tissue injury in the remnant liver. When PH was performed under Pringle maneuver, hepatocyte mitotic activity was substantially suppressed, although Pringle alone initiated a delayed regenerating response. Furthermore, Pringle maneuver deteriorated oxidative stress markers, markedly increased NF-kappaB activity, and aggravated tissue injury, as compared to hepatectomy alone. Mesna pretreatment prevented the Pringle-induced antimitotic effect and the induction of oxidative stress, inhibited the activation of NF-kappaB, while attenuating liver injury after PH under Pringle.

CONCLUSION

The excessive activation of NF-kappaB is related to the suppression of hepatocyte-regenerating activity following PH with concurrent liver ischemia. Mesna pretreatment protects the liver against the Pringle-induced antimitotic effect after PH via the prevention of oxidative stress and the inhibition of NF-kappaB activation.

Up-regulation of interleukin-6 gene expression in cyclophosphamide-induced cystitis in mice: An in situ hybridization histochemical study

AIM

To determine the time course and the cellular sources of interleukin (IL)-6 in the bladder during experimental cystitis, the expression of the IL-6 gene and IL-6 protein was examined in the bladder during cyclophosphamide (CP)-induced cystitis.

METHODS

Mice were killed at 0, 1, 2, 6, 12 and 48 h after the intraperitoneal administration of 0.9% saline containing either CP (200 mg/kg) or saline. The expression of IL-6 gene and IL-6 protein were detected using in situ hybridization histochemistry and immunocytochemistry, respectively.

RESULTS

In situ hybridization histochemistry showed that IL-6 gene expression was significantly up-regulated in the bladder at 1 h in comparison to that at 0 h after CP administration. The levels of IL-6 gene expression peaked at 6 h after CP administration and then declined thereafter. In contrast, only a few IL-6 transcripts were expressed in the bladder but they remained unchanged following the administration of saline at all time points examined. The IL-6 transcripts were predominantly distributed in the perivascular area of the submucosal layers during CP-induced cystitis. Immunocytochemistry demonstrated IL-6 immunoreactivity in the spindle-shaped cells located in the vicinity of the dilated vessels of the submucosal layers during CP-induced cystitis.

CONCLUSION

IL-6 gene expression was up-regulated in the submucosal layer of the bladder and peaked at 6 h after CP administration, suggesting that the primary source of IL-6 may be fibroblasts in the bladder during CP-induced cystitis.

Clinical pharmacokinetics of cyclophosphamide

Cyclophosphamide is an extensively used anticancer and immunosuppressive agent. It is a prodrug undergoing a complicated process of metabolic activation and inactivation. Technical difficulties in the accurate determination of the cyclophosphamide metabolites have long hampered the assessment of the clinical pharmacology of this drug. As these techniques are becoming increasingly available, adequate description of the pharmacokinetics of cyclophosphamide and its metabolites has become possible. There is incomplete understanding on the role of cyclophosphamide metabolites in the efficacy and toxicity of cyclophosphamide therapy. However, relationships between toxicity (cardiotoxicity, veno-occlusive disease) and exposure to cyclophosphamide and its metabolites have been established. Variations in the balance between metabolic activation and inactivation of cyclophosphamide owing to autoinduction, dose escalation, drug-drug interactions and individual differences have been reported, suggesting possibilities for optimisation of cyclophosphamide therapy. Knowledge of the pharmacokinetics of cyclophosphamide, and possibly monitoring the pharmacokinetics of cyclophosphamide in individuals, may be useful for improving its therapeutic index.

Mesna ameliorates intestinal mucosa damage after ifosfamide administration in the rabbit at a dose-Related manner

BACKGROUND

Cancer chemotherapy may lead to mucositis, a serious dose-limiting side effect. The alkylating agent ifosfamide is used in the treatment of various forms of cancer in combination with the uroprotective thiol mesna (2-mercaptoethane-sulfonate). The aims of this study were to assess the dose response intestinal mucosa damage of ifosfamide and to investigate the potential protective effect of mesna on rabbit intestinal epithelium.

MATERIALS AND METHODS

Fifty New Zealand White rabbits were randomly assigned to 10 groups of five animals each and received intravenously every week for 10 weeks either normal saline, ifosfamide, mesna, or ifosfamide plus mesna at three escalating dose levels (ifosfamide: 30, 45, or 60 mg/kg; mesna: 12, 18, or 24 mg/kg divided into two equal doses administered 4 h apart). Intestinal mucosa damage was assessed on the basis of crypt cell apoptosis and proliferation as well as intestinal morphometry. Apoptosis was detected by agarose gel electrophoresis and quantified by the DNA fragmentation assay and a standard terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick-end labeling (TUNEL) method by which the percentage of fragmented DNA and the apoptotic index were determined, respectively. The mitotic index and the crypt-villus (c/v) unit height were also measured in histological sections.

RESULTS

Ifosfamide caused a dose-related increase of crypt cell apoptosis and shortening of c/v unit, while it had a steady antimitotic effect. Mesna as a sole agent had no apoptotic or trophic effect on intestinal mucosa and hence no effect on intestinal morphometry. However, mesna, when administered concurrently with ifosfamide, ameliorated apoptosis, hypoproliferation, and mucosal atrophy at a dose-related manner.

CONCLUSIONS

Ifosfamide causes intestinal mucosa damage, which may be ameliorated in a dose-related manner by coadministration of mesna.

Clinical pharmacokinetics and pharmacodynamics of ifosfamide and its metabolites

This review discusses several issues in the clinical pharmacology of the antitumour agent ifosfamide and its metabolites. Ifosfamide is effective in a large number of malignant diseases. Its use, however, can be accompanied by haematological toxicity, neurotoxicity and nephrotoxicity. Since its development in the middle of the 1960s, most of the extensive metabolism of ifosfamide has been elucidated. Identification of specific isoenzymes responsible for ifosfamide metabolism may lead to an improved efficacy/toxicity ratio by modulation of the metabolic pathways. Whether ifosfamide is specifically transported by erythrocytes and which activated ifosfamide metabolites play a key role in this transport is currently being debated. In most clinical pharmacokinetic studies, the phenomenon of autoinduction has been observed, but the mechanism is not completely understood. Assessment of the pharmacokinetics of ifosfamide and metabolites has long been impaired by the lack of reliable bioanalytical assays. The recent development of improved bioanalytical assays has changed this dramatically, allowing extensive pharmacokinetic assessment, identifying key issues such as population differences in pharmacokinetic parameters, differences in elimination dependent upon route and schedule of administration, implications of the chirality of the drug and interpatient pharmacokinetic variability. The mechanisms of action of cytotoxicity, neurotoxicity, urotoxicity and nephrotoxicity have been pivotal issues in the assessment of the pharmacodynamics of ifosfamide. Correlations between the new insights into ifosfamide metabolism, pharmacokinetics and pharmacodynamics will rationalise the further development of therapeutic drug monitoring and dose individualisation of ifosfamide treatment.

Combined thin-layer chromatography-photography-densitometry for the quantification of ifosfamide and its principal metabolites in urine, cerebrospinal fluid and plasma

A method has been devised for the determination of the anticancer drug ifosfamide and its principal metabolites in urine, plasma and cerebrospinal fluid (CSF). The urine and CSF samples are absorbed onto Amberlite XAD-2 eluting the compounds of interest with methanol. Plasma is deproteinated using cold acetonitrile and centrifuged to yield a clear supernatant. The eluate and supernatant are analyzed by thin-layer chromatography, with spot visualization using 4-(4-nitrobenzyl)pyridine. The plates are photographed for subsequent densitometeric analysis. The intra-assay coefficient of variation for each compound in both urine and plasma was less than 10% and the lower limit of detection was 1 microgram/ml. The method provides a means of determining the full spectrum of metabolic products of ifosfamide in patients and will allow detailed investigation of variability in metabolism and pharmacokinetics of this drug.

Placebo-controlled double-blind comparative study on the preventive efficacy of mesna against ifosfamide-induced urinary disorders

In order to evaluate the preventive efficacy, safety and usefulness of mesna (Sodium 2-mercaptoethane sulfonate) against ifosfamide-induced urinary disorders, a placebo-controlled double-blind comparative study was performed. Ifosfamide was administered by intravenous drip infusion at a daily dose of 2 g/m2 for 5 consecutive days, and mesna was intravenously administered at 20% of the ifosfamide dose, three times daily for 5 consecutive days. The results obtained are as follows. (a) Of 101 accrued patients, 91 patients were evaluated consisting of 45 for the mesna group and 46 for the placebo group. There was no intergroup difference in the number of the evaluated cases and patient characteristics. (b) Micturition pain and feeling of residual urine graded as moderate or severe were not observed for the mesna group, but were observed for the placebo group with incidences of 19.6% (9/46) for micturition pain and 15.2% (7/46) for feeling of residual urine; the intergroup differences in the appearance of these urinary symptoms were statistically significant (P = 0.0003 for micturition pain; P = 0.0009 for feeling of residual urine). The incidence of hematuria graded as moderate or severe was 6.7% (3/45) in the mesna group, which was significantly lower than the 32.6% (15/46) in the placebo group (P = 0.0008). (c) No side-effect attributable to mesna was observed. (d) A judgment of "useful" was obtained in 80.0% (36/45) of the patients treated with mesna, which was significantly higher than the 34.8% (16/46) of the patients treated with placebo (P = near 0). On the basis of the above results, we conclude that the preventive efficacy, safety and usefulness of mesna against ifosfamide-induced urinary disorders have been well demonstrated in this study.

Solvent-sample interactions in thermospray mass spectrometry of antineoplastic nitrogen mustards

Conditions are reported for the optimization of thermospray mass spectrometric analysis of antineoplastic nitrogen mustard alkylating agents. In aqueous ammonium acetate mobile phase, multiple sequential solvolytic reactions occur with these highly labile compounds, and protonated molecular ions of the reaction products are observed. However, when high proportions of acetonitrile or other organic modifier are added to the mobile phase, solvolytic reactions are much reduced and abundant protonated molecular ions are detected. One exception to these observations is phosphoramide mustard, which solvolyses under all conditions attempted. A lower limit for detection of melphalan using direct injection and summing the ion current between m/z 120 and 870 is about 150 ng. Successful thermospray liquid chromatography/mass spectrometry of these compounds should be possible using high percentages of methanol in the mobile phase or increasing the organic content by post-column solvent modification.

Evaluation of the quantitative analysis of a steroid sulphate using fast atom bombardment and tandem mass spectrometry

Dehydroepiandrosterone sulphate (DHAS) has been quantified in human blood serum by fast atom bombardment (FAB)/tandem mass spectrometry of immunoadsorption extracts. FAB of DHAS yielded abundant ions corresponding to the intact steroid sulphate; these were selected by a double-focusing mass spectrometer prior to collisionally activated decomposition in a quadrupole collision cell and mass analysis by a quadrupole mass filter. [HSO4]- (m/z 97) was the sole prominent daughter ion. For quadrupole mass filter was set to transmit m/z 97 and a narrow-range magnet scan yielded a spectrum of parents, including m/z 367 and 369, corresponding to DHAS and the (2H2)-analogue (used as internal standard), respectively. Serum concentrations by this procedure were in good agreement with data obtained by gas chromatographic/mass spectrometric analyses of DHA heptafluorobutyrate, formed by direct derivatization of the steroid sulphate.