HPLC determination of morphine, morphine-3-glucuronide and morphine-6-glucuronide in human serum of oncological patients after administration of morphine drugs.

A simultaneous determination of morphine (M) and its two metabolites, morphine-3-glucuronide (M3G) and morphine-6-glucuronide (M6G), by HPLC in the serum of oncological patients is described. The compounds are extracted from the serum by means of Chromabond C18--EC solid-phase-extraction cartridges, separated on a Symmetry C18 analytical column (150 x 4.9 mm, 5 microm) and detected by a UV detector at 210 nm. The mobile phase consisted of 8% acetonitrile in water, 30 mmol/l phosphate buffer (pH 3) and 1 mmol/l octane sulfonic acid as the ion pairing agent; its flow-rate was 0.8 ml/min. Under these conditions, the detection limits were 10 ng/ml, 60 ng/ml and 90 ng/ml for M, M3G, and M6G, respectively. This paper concerns blood serum concentration levels of M, M3G and M6G in oncological patients, their ratios and their role in pain resistance.

Spectrofluorimetric determination of fendiline in tablets.

A simple, sensitive and accurate spectrofluorimetric method was developed for the assay of fendiline in tablets. Validation of the method provided good results concerning linearity, precision and accuracy. The linearity range was found to be 0.1-0.8 mg/l. The fluorescence intensity was measured at 288 nm for fendiline tablet solutions. It was also found that the excipients in the commercial tablets did not interfere with the method.

Rapid HPLC analysis of melphalan applied to hyperthermic isolation limb perfusion.

Hyperthermic isolated limb perfusion (HILP) with melphalan (MH) as a standard cytotoxic drug has been performed in 28 patients suffering from malignant melanoma. MH has been administered by HILP via extracorporeal circulation system. The drug given locoregionally reduces subsequent toxicity of organs. For all that residues can leak into the systemic circulation during HILP. Because of known carcinogenic potential and secondary cancer formation, the main interest of this work is to determine MH concentration profile in the patient plasma during and after HILP and evaluation of its potential toxicity in patients. Reversed-phase HPLC assay, which uses isocratic elution and fluorimetric detection has been shown to be sensitive, reliable and suitable for routine analyses. The assay was validated for the concentration range of 50-2500 ng.ml-1 with the limit of detection (LOD) 6.881 ng.ml-1. The samples were treated by methanol precipitation with the recovery more than 80%. The stability of standard solutions and methanolic extracts of MH were also followed. The concentration profile of MH in patient samples has been pursued in three time points during and after chemoperfusion (45 min after application of MH in extracorporeal circulation, 10 min after the joining the extremity to systemic circulation and one hour after the great vessels reconstruction). The concentrations of MH ranged 100-1500 ng.ml-1 and varied from patient-to-patient. Some complications were observed after HILP in 11 patients and are correlated with the higher con- centrations of MH (over 150 ng x ml-1) found in plasma.

Do vancomycin serum levels predict failures of vancomycin therapy or nephrotoxicity in cancer patients?

The purpose of this study was to determine if patients with high vancomycin (VAN) serum levels experience more toxicity than underdosed patients with lower (VAN) levels, and whether low VAN serum levels cause therapeutic failures in patients with gram-positive bacteremia. In 198 cancer patients trough and peak serum levels of VAN were measured. Acute toxicity (Red Man syndrome) appeared in 3 patients (1.5%). Patients previously or currently treated with other nephrotoxic compounds (134 patients) presented the same incidence of nephrotoxicity as those receiving VAN for the first time in monotherapy (64 patients). VAN did not increase the toxicity when patients were dosed simultaneously or previously with aminoglycosides or amphotericin B. Our second observation, when studying serum levels in our 198 patients was that high VAN trough serum levels (trough > 15 microg/mL) were associated with significantly more nephrotoxicity (33.3% vs. 11.1%, P < 0.03) than low levels in the subgroups of either pretreated patients or unpretreated with other nephrotoxic drugs. None of 198 patients who had trough levels below 15 microg/mL had peak levels exceeding 40 microg/mL. This suggests that only serum monitoring of trough levels may predict nephrotoxicity. A case control study was conducted to compare a group of 22 VAN failures with 22 successfully treated patients matched in underlying disease and neutropenia who were treated in the same period, under the same antibiotic policy, at the same cancer center, for gram-positive bacteremia. Persisting, enterococcal, or mixed enterococcal plus staphylococcal bacteremia were the only statistically significant risk factors which predicted therapy failure in cancer patients. Neither peak nor trough VAN serum levels predicted failure or cure of gram-positive bacteremia in cancer patients.

Do low vancomycine serum levels predict failures of vancomycine therapy in neutropenic cancer patients?

Vancomycine serum levels were measured in 198 cancer patients with documented grampositive bacteremia and twenty two failed. Failures were analyzed for risk factors of therapy failure. Only 8 of 22 showed low serum peak or through vancomycin levels. One patient was treated less than 7 days, 9 had persisting and 4 catheter associated bacteremia. Bacteremias due to VAN resistant strains were excluded. In 14 out of 22 patients, multiple or one risk factor could be determined, but in 8 patients, no risk factor was found. Hence the, case control study was conducted to compare the group of failures in 22 patients with a group of patients with underlying disease and neutropenia treated successfully within the same period and same antibiotic policy at the same cancer center, by VAN for gram-positive bacteremia. Persisting, catheter associated and enterococcal bacteremias were the only statistical significant risk factors predicting a therapy failure in cancer patients. Neither Vancomycine serum peak nor through levels predicted the outcome: failure or cure of gram-positive bacteremia in cancer patients. (Tab. 1, Ref. 5.).

[Determination of serum vancomycin using capillary isotachophoresis]. / Stúdium moznosti stanovenia vankomycínu v sére kapilárnou izotachoforézou.

The paper aims to study the possibilities of determining vancomycin in the serum by the method of capillary isotachophoresis. The leading electrolyte contained Na+ as the leading ion, morpholinoethanesulphonic acid as the counter-ion (pH 6,2), and methylhydroxyethyl cellulose as the additive. The terminating electrolyte was morpholinoethanesulphonic acid. The conductivity detector was employed for detection. Ethanol was selected for precipitation of proteins. The yield of vancomycin from the serum was 89-91%. The calibration curve is linear in an interval of 0.02-0.5 microgram (the absolutely dosed amount). The limit of vancomycin determination in the serum is 4 micrograms/ml. The method was employed to determine vancomycin in the serum of patients. The obtained results correlated well with those obtained by fluorescent polarizing immunoanalysis (TDx) in a concentration interval of 4-30 micrograms/ml.

Quantitative assay of verapamil in drugs and serum by capillary isotachophoresis.

Experimental conditions for a simple capillary isotachophoresis (ITP) with conductometric detection have been created for the determination of verapamil in drugs and serum. The limit of detection (LD) was 80 ng.cm-3 for standard verapamil solution. Under optimal experimental conditions and instrumental comparison, the LD of verapamil in serum was 420 ng.cm-3 without sample pretreatment. To lower the LD of verapamil in serum a liquid-liquid extraction was used. The high recovery (more than 94%) facilitated the verapamil ITP analysis at the therapeutic concentration.