S. Van Belle

Pharmacokinetics of mitoxantrone in humans following single-agent infusion or intra-arterial injection therapy or combined-agent infusion therapy

SummaryThis study describes the pharmacokinetics of mitoxantrone determined by a sensitive and specific HPLC-method.The time-concentration curves of i.v.-treated patients (15 mg/m2 over 30 min) correspond to a three-compartment model with a T1/2α of 12 min, a T1/2β of 93 min, and a slow elimination phase of 36 h.The central compartment volume was 26.22 and the distribution volume, 1381.9. The mean urinary excretion was 4.9% of the total dose.The pharmacokinetic parameters were also defined in five patients who were treated with combination chemotherapy (mitoxantrone 12 mg/m2, methotrexate 30 mg/m2 and vincristine 2 mg). These results were not different from those with the single-drug treatment, except for the volume of the central compartment, which was significantly decreased. The peak levels after hepatic arterial infusion of mitoxantrone were three times lower than those after the identical dose given i.v. to the same patient. Pleural fluid sampling showed a six-fold increase compared with the plasma level (12 ng/ml versus 2 ng/ml).A multiple linear regression analysis of the data revealed correlations between the pharmacokinetic results and some of the baseline parameters. It is possible to predict changes in the kinetic behaviour of mitoxantrone on the basis of these relations but on the other hand toxicity is less predictable from the baseline parameters or from the pharmacokinetic results.

High-performance liquid chromatographic determination of vinca-alkaloids in plasma and urine.

A liquid chromatographic method is described for separating and determining vinblastine, vincristine and vindesine in plasma and urine. The drugs are extracted from the biological material using an ion-pair extraction, with sodium octylsulphate as counter-ion at pH 3. The extracts are injected on a reversed-phase system with a cyano column as stationary phase and a mobile phase composed of acetonitrile-phosphate buffer, pH 3 (65:35, vol. %). Stability studies are carried out for stock solutions of the drugs in water at different temperatures and pH values. The stability of these compounds in plasma is also investigated in the presence of an antioxidant. The method is applied to determine drug levels of vindesine and vinblastine in preliminary pharmacokinetic studies, using vincristine as the internal standard.

Optimal combination therapy with tropisetron in 445 patients with incomplete control of chemotherapy-induced nausea and vomiting.

PURPOSEnThis study evaluated tropisetron (Navoban; Sandoz Pharma, Basle, Switzerland)-based combination therapy in patients who had incomplete control of chemotherapy-induced nausea or vomiting when using tropisetron as a single antiemetic agent.nnnPATIENTS AND METHODSnOne thousand seventy-two patients, who were scheduled to receive at least two identical cycles of emetogenic chemotherapy, were treated with 5 mg tropisetron once daily in their first chemotherapy course. A 2 x 2 x 2 factorial design was used to evaluate three additional treatments to the recommended 5 mg once daily (intravenously [i.v.] on day 1; orally on days 2 through 6) tropisetron regimen during course 2 in those patients who had shown incomplete control of nausea and/or vomiting on any day of course 1. Four hundred forty-five patients were centrally randomized to receive, in addition, open-label dexamethasone (day 1, 0.2 mg/kg i.v.; days 2 through 6, 8 mg orally) and/or open-label alizapride (day 1, 100 mg i.v. and 4 x 50 mg orally; days 2 through 6, 4 x 50 mg orally) and/or double-blind tropisetron (ie, doubling the dose to 10 mg once daily) or corresponding placebo.nnnRESULTSnComplete response rates (no nausea and no vomiting) were 72% for day 1 and 48% for days 1 through 6 of course 1. During course 2, more complete responders were observed when dexamethasone was added, both for day 1 (76% v 66%, P = .020) and for days 1 through 6 (50% v 34%, P = .0004). A moderate increase in the complete response rate was seen with the addition of conventional-dose alizapride (day 1, 75% v 68%, P = .14; days 1 through 6: 47% v 37%, P = .041). Doubling the dose of tropisetron did not change the complete response rate.nnnCONCLUSIONnThe addition of dexamethasone significantly increases the complete response rate of both acute and delayed emesis in patients who have incomplete disease control with tropisetron alone.

Ion-paired high-performance liquid chromatographic determination of mitoxantrone in physiological fluids

Mitoxantrone is one of the newer anthracenedione derivatives which has already been studied in phase I and II trials, where it has shown significant antitumor activity against a variety of human tumours. To determine the prolonged terminal half-life of mitoxantrone, we developed a sensitive high-performance liquid chromatographic method, providing a detection limit of 1 ng/ml of extracted serum. This system uses a C18 reversed-phase column. The mobile phase consists of a mixture of acetonitrile (30%, v/v) and an ammonium formate buffer (70%, v/v) with a pH of 2.7. Hexane sulphonic acid is added as an ion-pair former. Detection at a wavelength of 658 nm provides a highly selective system, showing no interfering peaks. Ametantrone, another anthracenedione derivative, is used as an internal standard. The extraction procedure for serum also uses hexane sulphonic acid in an ion-paired system. Because of the highly selective detection wavelength, urine samples can be injected without a sample clean-up procedure. This very sensitive method, combined with high selectivity and a fast and inexpensive serum clean-up procedure, has allowed us to document the prolonged terminal plasma half-life of mitoxantrone (levels of 2-5 ng/ml of plasma can still be detected six days after an intravenous infusion of 15 mg/m2 over 30 min). In urine an as yet unidentified metabolite was discovered.

Determination of vinca alkaloids in mouse tissues by high-performance liquid chromatography

A high-performance liquid chromatographic method is described for the determination of vinblastine in various normal mouse tissues, such as lung, heart, liver, kidney and muscles, and in implanted MO4 tumours. Vincristine was used as the internal standard. Freshly obtained mouse tissue or tumour tissue was frozen at -20 degrees C and then lyophilized. After lyophilisation, the dry tissues were pulverized and homogeneously mixed, and an aliquot was suspended in 0.1 M hydrochloric acid. The drugs of interest were then isolated from this suspension using ion-pair extraction at pH 3 with octylsulphate as counter-ion. The obtained extracts were analysed on a reversed-phase system with a cyanopropyl stationary phase. The detection limit was 1 ng/l in plasma and 10 ng/g in tissue. The extraction recoveries of vincristine and vinblastine were between 45 and 67%, and there were no interferences from blank components. Preliminary pharmacokinetic data for different mouse tissues and tumour implanted in muscle tissue are presented.

High-performance liquid chromatographic determination of navelbine in MO4 mouse fibrosarcoma cells and biological fluids

A high-performance liquid chromatographic method is described for separating and determining navelbine and possible metabolites in plasma, cell culture medium and MO4 cells. Navelbine is extracted from these fluids by ion-pair extraction with sodium octylsulphate as the counter-ion at pH 3. The system uses a cyano column as the stationary phase and a mobile phase of acetonitrile-0.12 M phosphate buffer (pH 3) (60:40, v/v). Application of the method to a study of the pharmacokinetic behaviour of navelbine in MO4 mouse fibrosarcoma cells is reported.

Is adjuvant treatment with vinblastine effective in reducing the occurrence of distant metastasis in limited squamous cell lung cancer? A randomized study

In order to study the usefulness of treatment with vinblastine (VLB) in the prevention of cancer metastasis in squamous cell lung cancer, 50 patients with locoregional disease were randomized to receive either locoregional RT alone (group A) or a weekly intravenous bolus injection of VLB (6 mg/m2) concurrently with and after locoregional radiotherapy (RT) (55 Gy in 6 weeks) until the appearance of metastases (group B). Neither the incidence of death with metastases, metastasis-free survival (MFS) nor overall survival (S) were significantly affected by treatment with the drug. However, due to the limited number of patients in each group, the power of the statistical test was such to allow only the detection of differences in MFS and S to or more than 80 per cent at theP=0.05 level. Local tumor response was significantly superior in group B (P<0.05). Acute toxicity (dysphagia, myelosuppression) during RT was significantly worse in group B. During long-term therapy with VLB, mild polyneuropathy developed in the majority of patients in group B. Furthermore, seven patients discontinued treatment with VLB during maintenance due to compliance (4) and excessive neurotoxicity (3).This treatment schedule with VLB is not recommended for patients with locoregional squamous cell lung cancer as significant toxicity is present during and after RT and significant increase in MFS and S is lacking. Because of an apparent increase in local response, the combination of VLB and RT merits further investigation in those tumors where local tumor control is crucial.