Metabolism pathway of vinorelbine (Navelbine) in human: characterisation of the metabolites by HPLC-MS/MS.

The biotransformation of vinorelbine (VRL), an anti-neoplastic vinca-alkaloid derivate already marketed for nonsmall cell lung cancer and advanced breast cancer as an i.v. form and currently registered in several countries as an oral form, was investigated in human. Biological specimen from several human sources constituted the material for the metabolic identification in human. An isocratic liquid chromatographic system composed of 40 mM ammonium acetate (pH 3) and acetonitrile was used for separation of the potential metabolites of VRL. Tandem mass spectrometry with positive electrospray ionisation was used to enable the structural identification of the metabolites. A total of 17 metabolites (12 directly obtained from VRL and 5 involving sequential step pathways) were characterised with proposed structures for most of the metabolites. All metabolites went through phase I reactions by the way of deacetylation, dealkylation, oxidation and hydroxylation. No conjugates were observed. Despite the high number of metabolites quantified, VRL was the major compound observed whatever the matrix. Most of the metabolites rapidly disappeared from blood, except 4-O-deacetyl vinorelbine which was slowly cleared. Most of the enzymatic pathways involved in the metabolites strongly suggested the major role of cytochrome P450 in the biotransformation of vinorelbine.

Development of a sensitive liquid chromatography method coupled with a tandem mass spectrometric detection for the clinical analysis of vinflunine and 4-O-deacetyl vinflunine in blood, urine and faeces.

A sensitive and specific liquid chromatographic method coupled with tandem mass spectrometric detection was set up and fully validated for the simultaneous quantification of vinflunine (VFL) and its pharmacologically active metabolite, 4-O-deacetyl vinflunine (DVFL). The two compounds, as well as vinblastine (used as internal standard), were deproteinised from blood and faeces, analysed on a cyano type column and detected on a Micromass Quattro II system in the positive ion mode after ionisation using an electrospray ion source. In blood, linearity was assessed up to 200 ng/ml for vinflunine and 100 ng/ml for 4-O-deacetyl vinflunine. The lower limit of quantification was validated at 250 pg/ml for both compounds. In other biological media, the linearity was assessed within the same range; the limit of quantification was adjusted according to the expected concentration levels of each compound. This method was first developed in order to identify the structures and to elucidate the metabolic pathway of vinflunine. Thanks to its high sensitivity and specificity, the method has enabled the quantification of vinflunine and 4-O-deacetyl vinflunine in blood at trace levels, and has contributed to the knowledge of vinflunine metabolism by monitoring up to 10 metabolites.

A high performance liquid chromatography method for vinorelbine and 4-O-deacetyl vinorelbine: a decade of routine analysis in human blood.

A sensitive high performance liquid chromatographic method was developed and validated for the simultaneous quantification of vinorelbine and its active metabolite, 4-O-deacetyl vinorelbine, in human biological fluids. These two compounds together with vinblastine, used as internal standard, were extracted from blood and urine by a liquid-liquid process using diethyl ether, and followed by a back-extraction in acidic conditions. Then, they were analysed through a cyano column and detected in ultraviolet at 268 nm. The assay linearity was validated up to 2000 ng/ml. The lower limit of quantification was set at 2.5 ng/ml. The between-run precision and accuracy were always higher than 94%. Biological samples were stable when stored at -80 degrees C over 2 years. The long-term reproducibility and the suitability of this analytical method were demonstrated within the last decade through the analysis of about 7000 samples during the clinical development of i.v. and oral formulations of vinorelbine. Because vinorelbine binds mainly to platelets and blood cells and because this binding is rapidly reversible and highly influenced by environmental conditions, drug concentration in plasma may be highly influenced by the sampling conditions and the centrifugation process used to separate blood cells from plasma. Therefore, this method was developed in blood and then used for sample analyses in routine. The major benefit was that it was easy for nurses to directly collect blood instead of plasma and that reduced volume of sampling could be withdrawn from frail patients. Furthermore, the analysis in blood enabled to quantify vinorelbine and 4-O-deacetyl vinorelbine concentrations for a longer period of time, which resulted in a more accurate evaluation of pharmacokinetic parameters.

Pharmacokinetics of zidovudine in patients with liver cirrhosis.

The pharmacokinetics of zidovudine (azidothymidine, AZT) was investigated after oral administration (200 mg) in 14 human immunodeficiency virus seronegative patients with liver cirrhosis. They were divided in three groups according to the severity of the liver disease quantitated by the Child-Pugh score. Plasma and urine concentrations of zidovudine and its glucuronidated metabolite (GAZT) were measured simultaneously by HPLC assay. Findings were compared with those previously measured in six healthy volunteers. As a consequence of a marked drop in oral clearance (10 +/- 4 versus 38 +/- 15 ml/min/kg), zidovudine concentrations, half-life, and mean residence time were increased in patients with cirrhosis. No difference could be established between the three groups. The reason for such a decrease in oral clearance of zidovudine was the reduction in the GAZT formation clearance (236 +/- 73 versus 1540 +/- 540 ml/min); this led to a decrease in the AUC ratio of GAZT and zidovudine (1.3 +/- 0.6 versus 4.6 +/- 0.7), which was directly related to the severity of the cirrhosis. In patients, as in volunteers, formation of GAZT rate limits its elimination. To avoid important cumulation of zidovudine after repeated dosing in patients with acquired immunodeficiency syndrome who have hepatic impairment, a dosage adjustment could be proposed.

New sensitive liquid chromatography method coupled with tandem mass spectrometric detection for the clinical analysis of vinorelbine and its metabolites in blood, plasma, urine and faeces.

A new sensitive and specific liquid chromatographic method coupled with tandem mass spectrometric detection was set up and validated for the simultaneous quantitation of vinorelbine, its main metabolite, 4-O-deacetylvinorelbine and two other minor metabolites, 20'-hydroxyvinorelbine and vinorelbine 6'-oxide. All these compounds, including vinblastine (used as internal standard) were deproteinised from blood, plasma and faeces (only diluted in urine), analysed on a cyano column and detected on a Micromass Quattro II system in the positive ion mode after ionisation, using an electrospray ion source. Under tandem mass spectrometry conditions, the specific product ions led one to accurately quantify vinorelbine and its metabolites in all biological fluids. In whole blood, linearity was assessed up to 200 ng/ml for vinorelbine and up to 50 ng/ml for the metabolites. The limit of quantitation was validated at 250 pg/ml for both vinorelbine and 4-O-deacetylvinorelbine. In the other biological media, the linearity was assessed within a same range and the limit of quantitation was adjusted according to the expected concentrations of each compound. This method was initially developed in order to identify the metabolite structures and to elucidate the metabolic pathway of vinorelbine. Thanks to its high sensitivity, this method has enabled the quantitation of vinorelbine and all its metabolites in whole blood over 168 h (i.e., 4-5 elimination half lives) whilst the previous liquid chromatographic methods allowed their measurement for a maximum of 48-72 h. Therefore, using this method has improved the reliability of the pharmacokinetic data analysis of vinorelbine.

[Evaluation of an immunological new kit used in the toxicological screening of benzodiazepines in hospital emergency care units]. / Evaluation d'une nouvelle trousse immunologique utilisée dans le dépistage toxicologique des benzodiazépines en médecine d'urgence hospitalière.

Benzodiazepines are mostly used for their antianxiety and sedative effects. In recent years, new compounds have been developed with a hypnotic action. Although marked toxicity is uncommon with the use of these compounds, the clinician requires a rapid laboratory report in emergency and intensive care units in case of self-poisoning. To reduce the incidence of false-negative results routinely observed with our enzyme immunoassay kit (Emit tox benzodiazepine), the performance of a new kit (Emit dau benzodiazepine) was evaluated in 57 patients who had taken an overdose of benzodiazepines. Results were compared with those obtained by high performance liquid chromatography (HPLC) using a diode array detector and giving a semi-quantitative result. Seventy-four percent of the patients studied gave readings above the cut-off value, which was consistent with benzodiazepine intoxication, according to the results of the specific HPLC analysis (bromazepam, triazolam, alprazolam and flunitrazepam were clearly identified). No false negatives were obtained in this study with the Emit dau benzodiazepine. Finally, HPLC is unsuitable in the emergency setting; the enzyme multiplied immunoassay technique is the most appropriate method used in cases of self-poisoning with benzodiazepines having a low therapeutic index.

A phase 1 study of vinflunine in combination with trastuzumab for the treatment for HER2-positive metastatic breast cancer.

OBJECTIVE: To determine the recommended dose (RD) of vinflunine in combination with trastuzumab in human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer (MBC) and to investigate potential pharmacokinetic (PK) interactions. PATIENTS AND METHODS: In the first part of the study, two dose levels of vinflunine given every 3 weeks were explored (280 and 320 mg/m(2)) combined with trastuzumab (4 mg/kg loading dose and 2 mg/kg weekly). For each level of dose, six patients were enrolled to determine the RD for phase 2 studies (RP2S). In the second part of the study, 18 additional patients at RP2S have been evaluated to confirm safety and investigate preliminary antitumor activity. RESULTS: The RD was 320 mg/m(2) according to the dose escalation plan. Eleven of 15 additional patients who received this dose experienced dose-limiting toxicities, leading to a reduction in the RD to 280 mg/m(2). When compared to prior trials when vinflunine was used as a single agent, neither vinflunine total blood clearance nor trastuzumab serum concentrations were modified when the drugs were combined. All patients were evaluable, and the overall response rate was 73.3 % (95 % CI 54.1-87.7). The median progression-free survival was 11.3 months (95 % CI 9.4-21.0). At the dose of 280 mg/m(2), grade 3-4 neutropenia were seen in 4 patients (44.4 %) without febrile neutropenia. Non-hematologic grade 4 toxicities were not reported while grade 3 peripheral sensory neuropathy concerned 2 patients (22.2 %). CONCLUSION: The RD of vinflunine in combination with the standard regimen of trastuzumab is 280 mg/m(2) every 3 weeks. No mutual PK drug-drug interaction was seen. This regimen appears to be active with a favorable safety profile. Its role in HER2-positive MBC treatment needs to be defined in prospective comparative clinical trials.

Absorption of zidovudine in patients with diarrhoea.

Many patients with AIDS have gastrointestinal complaints, including the major clinical disorder of chronic diarrhoea. The pharmacokinetics of zidovudine was studied in 9 male patients with HIV infection and diarrhoea to establish whether drug absorption was impaired in them. The peak plasma concentration and AUC after a single oral dose of 200 mg, were the same as those reported in 6 healthy male volunteers (3.1 vs 4.0 mumol.l-1 and 7.2 vs 5.2 mumol.h.l-1, respectively). Since the bioavailability of zidovudine is not particularly impaired, oral zidovudine therapy can be maintained in patients with diarrhoea.

[Severe poisoning with intravenous phenytoin in the newborn. Value of peritoneal dialysis]. / Intoxication grave par la phénytoïne intraveineuse chez le nouveau-né. Intérêt de la dialyse péritonéale.

A severe poisoning with intravenous phenytoin in a newborn was treated with peritoneal dialysis in spite of its reported poor effectiveness, the drug being 90% protein-bound. During 10 hours, 1.41 mg/hr were eliminated by biotransformation and 1.80 mg/hr were removed with peritoneal dialysis allowing to suppress quickly life threatening cardiac side effects. This efficacy may be explained by an increase in the unbound protein fraction and a diffusion speed through the peritoneum higher than in older patients.

Pharmacokinetics of foscarnet after twice-daily administrations for treatment of cytomegalovirus disease in AIDS patients.

The pharmacokinetics of foscarnet were evaluated in 11 AIDS patients with cytomegalovirus disease after twice-daily infusion of 90 mg/kg of body weight for 2 weeks. All patients were hydrated during foscarnet infusion. Blood and urine samples were collected on days 1, 7, and 14 of therapy. Foscarnet concentrations were measured by high-pressure liquid chromatography. Despite large interindividual variations, no significant differences were seen between day 1, day 7, and day 14 concentrations in plasma. Mean peak and trough concentrations on day 14 of therapy were 605 +/- 118 and 52 +/- 59 microM, respectively. In all patients, peak concentrations were well above those necessary to inhibit cytomegalovirus. Pharmacokinetic parameters remained stable throughout the study. On day 14, the mean half-life was 3.4 h, total and renal clearances were 118 and 92 ml/min, respectively, and the volume of distribution was 0.6 liter/kg. These data and previous clinical trials demonstrate that this more convenient dosage regimen can be safely used for patients with cytomegalovirus disease. The side effects were comparable to those reported with other dosage regimens, although no renal impairment was seen in this study, probably because of the hydration.