Analysis and behavior of colistin during anaerobic fermentation.

A new analytical method for the determination of colistin in fermenter samples was developed followed by a study on the behavior of this substance during anaerobic fermentation. Analysis of colistin A and B was carried out by liquid chromatography-tandem mass spectrometry. Separation of the analytes was performed on a Security Guard column (4×3mm). Fourteen fermentation tests in batch as well as in continuous reactors were carried out. After 44days of anaerobic digestion of cattle manure, initially spiked with 500mg/kg of colistin sulfate, a considerable decrease of the colistin concentration to less than 1mg/kg could be observed. Furthermore, the daily production of biogas and methane was measured. A correlation between gas production and colistin concentration could not be determined. However, an increase of 10% of the cumulative methane production was observed in those fermenters spiked with an initial bolus of 500mg/kg colistin.

Cytotoxic drug residues in urine of dogs receiving anticancer chemotherapy.

BACKGROUND: The presence of cytotoxic drug residues in urine of dogs may represent an exposure risk for pet owners and other people as well as a potential environmental contaminant. However, studies on cytotoxic drug residues in excretions of clinical patients are lacking in veterinary oncology. HYPOTHESIS: Variable concentrations of cytotoxic residues are present in urine samples, depending on sampling time and substance. ANIMALS: Client-owned dogs with lymphoma or mast cell tumors treated with standard chemotherapy protocols. METHODS: Urine samples were collected before, directly after, and on days after administration of chemotherapy. Measurement of vincristine, vinblastine, cyclophosphamide, and doxorubicin residues in canine urine was performed by a quantitative liquid chromatography tandem mass spectrometry (LC/MS/MS) method. RESULTS: Median cyclophosphamide residue concentration was 398.2 microg/L directly after treatment (d0) and was below the level of detection on days 1-3 (d1, d2, d3). Median vincristine residue concentration was 53.8 microg/L directly after treatment and was 20.2, 11.4, and 6.6 microg/L on days 1, 2, and 3. Median vinblastine residues were 144.9 (d0), 70.8 (d1), 35.6 (d2), and 18.7 microg/L (d3) with low concentrations detectable for 7 days after treatment. Median urine doxorubicin concentrations were 354.0 (d0), 165.6 (d1), 156.9 (d2), and 158.2 microg/L (d3). Low concentrations of doxorubicin were measurable up to 21 days after administration. CONCLUSIONS AND CLINICAL IMPORTANCE: Variable concentrations of chemotherapeutics were measured in urine samples, depending on sampling time point and drug. Findings may inform current chemoprotection guidelines and help minimize exposure risks.

Drug residues in serum of dogs receiving anticancer chemotherapy.

BACKGROUND: The presence of drug residues in blood samples can represent an occupational hazard. However, studies on cytotoxic drug residues in serum of dogs are lacking in veterinary oncology. OBJECTIVE: To evaluate possible occupational hazards associated with handling of blood samples from dogs receiving oncolytic drugs 7 days after treatment. ANIMALS: Twenty-seven client-owned dogs treated for lymphoma or mast cell tumors with vincristine, vinblastine, cyclophosphamide, or doxorubicin. METHODS: Prospective, observational study. Serum samples were either taken 7 days after administration of vincristine, cyclophosphamide, doxorubicin (lymphoma), and vinblastine (mast cell tumor), or 1-2 days after the last concurrent oral administration of cyclophosphamide (mast cell tumor). Additionally, serum was collected within 5 minutes of treatment. Measurement of drug residues in serum was performed by liquid chromatography tandem mass spectrometry (LC/MS/MS). RESULTS: In 33 samples collected within 5 minute of treatment, the median serum concentrations were vincristine: 37 microg/L (range: 11-87 microg/L), vinblastine: 13 microg/L (range: 13-35 microg/L), cyclophosphamide: 2,484 microg/L (range: 1,209-2,778 microg/L), doxorubicin: 404 microg/L (range: 234-528 microg/L). In 81 serum samples collected 7 days after treatment vinblastine (7 microg/L) was detected in 1 sample, and cyclophosphamide (7 and 9 microg/L) in 2 samples collected 1-2 days after oral administration of cyclophosphamide. Medications were not detected in any of the other samples. CONCLUSIONS AND CLINICAL IMPORTANCE: Handling of blood samples from dogs receiving oncolytic chemotherapy 7 days after treatment with vincristine, vinblastine, cyclophosphamide, and doxorubicin should not present a health hazard.