Pharmacokinetics and toxicity of 5-day continuous infusion of vinblastine

The clinical pharmacology and use of antimicrotubule agents in cancer chemotherapeutics

Although there has been a rapid expansion of the number of classes of compounds with antineoplastic activity, few have played a more vital role in the curative and palliative treatment of cancers than the antimicrotubule agents. Although the vinca alkaloids have been the only subclass of antimicrotubule agents that have had broad experimental and clinical applications in oncologic therapeutics over the last several decades, the taxanes, led by the prototypic agent taxol, are emerging as another very active class of antimicrotubule agents. After briefly reviewing the mechanisms of antineoplastic action and resistance, this article comprehensively reviews the clinical pharmacology, therapeutic applications, and clinical toxicities of selected antimicrotubule agents.

Human granulosa-luteal cell response to vinblastine exposure in vitro

We examined the response of isolated human granulosa-luteal cells (HGLCs) to a cancer chemotherapeutic agent, vinblastine (VLB), that has been implicated in ovarian failure during treatment for Hodgkin's disease. VLB doses of 1.0 micrograms/mL for 4 h or 0.1 micrograms/mL for 24 h reduced HGLC progesterone production during exposure. The effect of high doses (10.0 and 100.0 micrograms/mL) persisted for at least 1 day after exposure. Previous 24 h, but not 4 h, high-dose VLB exposure reduced subsequent progesterone release in response to 10 IU of human chorionic gonadotropin (hCG). Without hCG stimulation, only cells previously exposed to 100.0 micrograms/mL had persistently reduced progesterone release. We conclude that HGLCs can completely recover from a short exposure to VLB, but longer exposures to 10.0 and 100.0 micrograms/mL are detrimental to their hormone secreting capacity.

Pharmacokinetics of navelbine after oral administration in cancer patients

The pharmacokinetic behavior of navelbine was investigated in 19 patients presenting with advanced cancers (mainly women with breast cancer). Navelbine was given orally at seven dose levels of up to 200 mg/week. For a given dose, patients received four successive weekly treatments. Five subjects also received two different doses. After drug administration, plasma was collected for 48 or 72 h and monitored for navelbine concentration by radioimmunoassay. Absorption of navelbine was very rapid after oral administration: maximal drug concentrations were reached within the first 1 or 2 h (Tmax, 0.9-1.75 h; cmax, 70.9-832.6 ng/ml), with absorption constants ranging from 0.85 to 2.42 l/h. A comparison of dose-normalised plasma concentration profiles revealed significant time dependence in six evaluable patients (P less than 0.001). Only four subjects who received low doses (less than or equal to 100 mg/week) exhibited time-independent kinetics. All of the five patients who were treated at different doses displayed apparent dose dependence (P less than 0.001). No individual profile was characterised by both time- and dose-independent pharmacokinetics. In all, 18 patients presented biphasic plasma concentration-decay patterns, and only 1 subject exhibited monophasic decay kinetics. The navelbine pharmacokinetic parameters obtained following oral administration were similar to those observed after i.v. bolus injection and were characterised by high oral clearance (0.43-1.45 1 h-1 kg-1), a large apparent volume of distribution (27.4-45.9 1/kg), and a long terminal half-life (24.2-56.5 h). Large intra- and inter-individual variations in pharmacokinetic parameters were observed. Moreover, after a high dose of 200 mg, an enterohepatic cycle and/or a delay in navelbine's absorption at a distal intestinal site as evidenced by a marked plasma level rebound was observed.

In vivo and in vitro pharmacokinetics and metabolism of vincaalkaloids in rat. II. Vinblastine and vincristine

Vinblastine and Vincristine pharmacokinetics, including tissue distribution, metabolism and biliary excretion, were investigated, using both "in vitro" and "in vivo" models, after i.v. injections in rats. Plasma kinetic curves were best fitted to a two-compartment open model. The average terminal half-lives of VLB and VCR were 14.3 h and 7.5 h, respectively. The systemic clearance and apparent distribution volume for VLB, respectively 1.49 l/h/kg and 11.46 l/kg, were significantly greater than those of VCR, 0.12 l/h/kg and 0.41 l/kg. VCR was found to be widely distributed in tissues after i.v. injections in rats. The highest drug accumulation site was the intestine (122.0 ng/g wet tissue at 24 h). Liver and kidneys also retained high proportions of drug (respectively, 47.0 ng/g and 44.4 ng/g at 24 h). Biliary excretion was more rapid for VCR (42.7% of total radioactivity excreted over 24 h) than VLB (28.2% of total dose over 24 h). For both molecules, the percentage of radioactivity excreted in bile over 30-48 h ranged between 40-50% of total dose. At high doses, either biliary excretion rate or cumulated excretion was reduced. High performance liquid chromatography analysis of bile samples revealed four biotransformation products for VLB and three for VCR. When incubated in freshly isolated rat hepatocytes, VLB penetrated more rapidly and intensely into the cells (more than 90% of total dose taken up over 20 min) than VCR (only about 40% accumulated), probably through a passive diffusion mechanism followed by tight cellular binding. "In vitro" metabolism patterns were similar to those found "in vivo", except for the most polar metabolites observed "in vitro". Two anti-Vinca monoclonal antibodies with different specificities were used to test VCR metabolite immunoreactivities. The results suggested that some structural modifications occurred in the catharantine moiety of the molecule but that the dimeric structure seemed to be well conserved after biotransformation.

ViVACCy--a drug schedule based on G2 blockade and prolonged infusion of multiple tubulin-binding agents. A pilot study

A drug schedule has been devised based on a strategy of G2 blockade followed by prolonged infusion of tubulin-binding agents. The regimen consists of doxorubicin 32 mg/m2 i.v. and cyclophosphamide 320 mg/m2 i.v. on day 1 followed by vinblastine (0.3 to 1.2 mg/m2/day), cisplatin (3 to 12 mg/m2/day), and vincristine (0.04 to 0.16 mg/m2/day) by continuous intravenous infusion on days 5 to 12. Courses are repeated every 28 days. Eighteen patients with advanced solid tumors received 37 courses of chemotherapy in a pilot study to determine safe drug concentrations for the three-drug infusion for 7 days. Dose limiting toxicity was myelosuppression. Patients who received prior mitomycin-C experienced more profound thrombocytopenia than those who did not. Nonhematologic toxicities included mild nausea, vomiting, and transient elevations of serum alkaline phosphatase and serum creatinine. One patient with squamous cell carcinoma of the esophagus who erroneously received vincristine 0.8 mg/m2 instead of 0.08 mg/m2 for 4 1/2 days developed transient myalgia, ileus, and a transient peripheral neuropathy; the patient achieved a sustained complete remission for 15 months and died of unrelated causes. Minor responses and stable disease were seen in two patients with renal cell carcinoma (1 and 2.5 months), three patients with colorectal carcinoma (1.5, 2, and 4 months), and one patient with squamous cell carcinoma of the tongue (2 months). The ViVACCy drug regimen can be given without undue toxicity and may be active in solid tumors.

Studies on the stability of vinblastine sulfate in aqueous solution

A stability study on vinblastine sulfate (1) in aqueous solution at several different temperatures (in the absence of light) has been undertaken. High-performance liquid chromatography was used to obtain kinetic data for the loss of vinblastine and to monitor the order of appearance of degradation products, of which eight were observed. The two most prominent components of early heat degradation have been tentatively identified by mass spectrometry (DCl), as a C19'-oxidation product (19'-oxovinblastine, 4, MH+ 825) and an isomer of vinblastine (MH+ 811). Products appearing later in the course of degradation include a component of MH+ 809, possibly corresponding to either 19'-hydroxy-3',4'-dehydrovinblastine (5) or 3',4'-dehydrovinblastine-6'-N-oxide (6), and three other products of MH+ 636, MH+ 670, and MH+ 795. In addition, optical rotation studies have established that racemization (with a possible reduction in biological activity) does not occur prior to transformation into degradation products. Preliminary experiments on light-mediated degradation demonstrated a different sequence of transformation, with the MH+ 670 and MH+ 795 products appearing first. Contrary to reports and suggestions in the literature and based on an estimated activation energy of 27.1 kcal/mol, the results of this study indicate that vinblastine sulfate is relatively stable in aqueous solution at or below room temperature (estimated t90 values: 150 d at 25 degrees C and 10.7 years at 5 degrees C) and has a t90 value of 16.6 d at 37 degrees C. These results are important in view of current interest in the continuous iv infusion of vinblastine sulfate.(ABSTRACT TRUNCATED AT 250 WORDS)