A simple and sensitive high-performance liquid chromatographic method for the determination of vinflunine and 4-O-deacetylvinflunine from human blood.

Vinflunine (VFL) is the first bifluorinated tubulin-targeted agent obtained through a semi synthetic process using superacidic chemistry. Pharmacologic models evidenced a high degree of activity from several cancer lines. The intravenous formulation of VFL (Javlor, Pierre Fabre Medicament, Boulogne, France) is registered for bladder cancer and is undergoing Phase III trials for nonsmall cell lung and breast cancer. To support most of the pharmacokinetic studies in humans, a sensitive high-performance liquid chromatography bioanalytical method coupled with ultraviolet detection was developed and validated for the simultaneous quantification of VFL and its active metabolite 4-O-deacetylvinflunine. The two compounds, together with 17-bromovinorelbine, used as an internal standard, were extracted from blood (1 mL) by a liquid-liquid process under basic conditions using diethyl ether. The organic phase was then back-extracted with HCl 0.1 mol/L. Analysis was performed through a cyano column and detection was set at 268 nm. Total analysis run time was less than 15 minutes. The assay was sensitive for the two compounds to at least 2 ng/mL and calibration curves were linear up to 200 ng/mL. The between-run imprecision and the mean inaccuracy were lower than 7% and 8.3%, respectively. Blood samples were stable when stored at -70°C over 24 months. The long-term reproducibility and the suitability of this analytical method were demonstrated through the analysis of about 6000 biologic samples during the clinical development of intravenous VFL. This method is adequately sensitive to monitor the blood concentrations observed at the recommended dose defined in a clinical setting.

Phase I/II and pharmacokinetic study of intravenous vinflunine in combination with cisplatin for the treatment of chemonaive patients with advanced non-small-cell lung cancer.

BACKGROUND: A multicenter phase I/II trial of vinflunine administered in combination with cisplatin at 80 mg/m(2) was conducted in order to determine the dose-limiting toxicities, the maximum tolerated dose, and the recommended dose of the combination. An eventual mutual pharmacokinetic drug-drug interaction when vinflunine and cisplatin were coadministered was also evaluated. The study was also intended to define the response rate of vinflunine in combination with cisplatin as first-line chemotherapy in patients with advanced non-small-cell lung cancer (NSCLC) at the recommended dose. PATIENTS AND METHODS: Patients were required to have a histologically confirmed diagnosis of NSCLC not amenable to curable treatment or stage IV disease. Patients may have had previous surgery for NSCLC but were to be chemonaive and have at least 1 bidimensional measurable lesion outside an irradiated area. RESULTS: The recommended dose was established at cisplatin 80 mg/m2 combined with vinflunine 320 mg/m(2). No unexpected adverse events were seen. Pharmacokinetic analysis supported the absence of mutual pharmacokinetic interaction when vinflunine and cisplatin are given in combination. Treatment of 53 patients at this recommended dose demonstrated a tumor response rate of 32.1% in the intent-to-treat population; disease control was achieved in 79.2% of the patients. The median progression-free survival and overall survival were estimated at 5 months and 10.4 months, respectively, and the 1-year survival rate was 43.4%. CONCLUSION: These results place the vinflunine/cisplatin combination among the most active doublets in this treatment setting and warrant further development in phase III trials of first-line treatment of patients with advanced metastatic NSCLC.

Novel pharmacokinetic behavior of intravenous busulfan in children with thalassemia undergoing hematopoietic stem cell transplantation: a prospective evaluation of pharmacokinetic and pharmacodynamic profile with therapeutic drug monitoring.

We prospectively studied the pharmacokinetics (PK) and clinical outcomes of intravenous busulfan (Bu) in 71 children with preexisting liver damage who underwent hematopoietic stem cell transplantation for thalassemia. Intravenous Bu was administered every 6 hours as part of a conditioning regimen with PK-based dose adjustment to target a conservative area under the concentration-versus-time curve (AUC) range (900-1350 microMol*min). The first-dose Bu clearance (CL) was significantly higher than the subsequent daily CL that remained unchanged in the ensuing days. One-third of patients required dose escalation based on dose 1 AUC, whereas dose reduction was needed in the subsequent days. At doses 5, 9, and 13, 78%, 81%, and 87% of patients, respectively, achieved the target range of AUC. A population PK analysis confirmed that the first-dose CL was 20% higher and that body weight was the most important covariate to explain PK variability. Patients with variant GSTA1*B had a 10% lower Bu CL than wild-type. These results suggest that the disease-specific behavior of intravenous Bu PK should be considered for PK-guided dose adjustment in patients with thalassemia, and the use of a conservative AUC range resulted in low toxicity, good engraftment, and good survival rate.

Mild to moderate liver dysfunction does not require dose reduction of oral or intravenous vinorelbine: results of a pharmacokinetic study.

We studied the pharmacokinetic profile of weekly oral and intravenous vinorelbine in cancer patients with various degrees of hepatic function, and assessed an intra-patient comparison of the pharmacokinetics of i.v. versus oral vinorelbine. In this open-label study, patients were randomised to receive an initial dose of vinorelbine at day 1 by either i.v. or the oral route followed by a second dose on day 8 via the alternative route. A total of 16 patients were included, 12 patients received the planned two administrations. Toxicities were similar for all cohorts and were mainly of haematological and gastrointestinal origin. Pharmacokinetic analysis of both routes did not reveal any differences between cohort I and II. Based on these findings in patients with mild to moderate liver dysfunction no dose modifications of vinorelbine have to be taken into consideration.

Dose-ranging study of metronomic oral vinorelbine in patients with advanced refractory cancer.

AIM: To determine the safe dose range and pharmacokinetics of metronomic oral vinorelbine and obtain preliminary data on biomarkers and efficacy in patients with advanced cancer. METHODS: Successive cohorts of patients received escalated doses of oral vinorelbine given thrice a week until disease progression, unacceptable toxicity (UT), or consent withdrawal. UT was any grade 4 toxicity, or grade 2 or 3 toxicity that would result to longer than 2-week break during the first 2 months of treatment. Blood samples were collected for pharmacokinetics and quantification of angiogenesis regulatory proteins. RESULTS: Sixty-two patients (median age, 60 years) enrolled at six dose levels from 20 to 70 mg and received treatment for median 12.25 weeks (range, 2-216+). Unacceptable toxicity occurred in two of six patients treated at 60 mg (leucopenia grade 4 and epistaxis grade 2) and in one at 70 mg (leucopenia grade 2). The upper metronomic dose was 50 mg. Objective antitumor response documented in eight cases and 32% of patients experienced disease stability for minimum 6 months. Three responders (renal cancer, medullary thyroid carcinoma, and Kaposi sarcoma) received nonstop treatment for over 3 years without overt toxicity. Low pretreatment levels of circulating interleukin-8, vascular endothelial growth factor, and basic fibroblast growth factor were found predictors of efficacy. Steady-state concentrations of vinorelbine and its active metabolite ranged from 0.5 to 1.5 ng/mL. CONCLUSIONS: Metronomic administration of oral vinorelbine is feasible at doses up to 50 mg thrice a week and can yield sustainable antitumor activity without overt toxicity, probably through antiangiogenic mechanism. Further clinical investigation is warranted.

Combination chemotherapy of vinorelbine and cisplatin: a phase I pharmacokinetic study in patients with metastatic solid tumors.

BACKGROUND: Vinorelbine (VRL)-cisplatin (CDDP) is an active doublet for advanced non-small cell lung cancer. CDDP has a narrow therapeutic index and may produce a cumulative nephrotoxicity over the treatment period. This study was to assess the risks of drug-drug interaction (DDI) over 3 consecutive cycles of VRL-CDDP combined treatments. PATIENTS AND METHODS: An open-label, nonrandomised, phase I study was carried out. Patients with normal hepatic/renal functions. D1: CDDP 100 mg/m2--D1, D8: oral VRL 60 mg/m2 q3w. Pharmacokinetics (PK) over the first 3 cycles. PK comparison between cycles and between study vs. literature. RESULTS: Thirteen patients were evaluable for safety and PK. Adverse events were those frequently observed with CDDP or VRL, and consisted of hematological toxicities, nausea, vomiting and constipation. Concerning VRL and CDDP PK, no difference was detected between the 3 administrations nor between the study and reference values. CONCLUSION: The absence of DDI between CDDP and oral VRL was demonstrated over 3 consecutive cycles of therapy.

Pharmacokinetics, metabolites, and preclinical safety of vinflunine.

The novel microtubule inhibitor, vinflunine, has a unique mechanism of action that differs from other members of the vinca alkaloid class in terms of tubulin-binding affinity, microtubule dynamics, spiral formation, and intracellular accumulation. Vinflunine has shown significant activity in vivo, which involves its antimitotic, antiangiogenic, and antivascular properties. The promising preclinical activity of vinflunine has warranted further investigation in the clinical setting. This review explores the distinct interaction of vinflunine with its intracellular targets to gain insight into its mechanism of action and safety profile. The pharmacokinetic properties and metabolism of vinflunine in animals and in human subjects are also discussed, together with an analysis of potential drug-drug interactions and the influence of age, liver dysfunction, or renal dysfunction on the overall activity of vinflunine.

Oral vinorelbine in the treatment of non-small cell lung cancer: rationale and implications for patient management.

Vinorelbine is an established treatment for advanced non-small cell lung cancer (NSCLC), both as a single agent and in combination chemotherapy. Recently, an oral form of this agent has been developed. Before accepting an established agent in a different administration form, rigorous testing is required to answer such questions as reliable bioavailability, continued safety and preservation of efficacy. In addition, an oral agent must provide patient convenience and acceptance, while being an economically sound approach. Oral vinorelbine was found to have acceptable and reliable pharmacokinetic profiles at clinically relevant dosage levels. Oral vinorelbine was found to have approximately 40% bioavailability; thus, a dose of 80 mg/m(2) orally is the equivalent of 30 mg/m(2) intravenously, and 60 mg/m(2) orally is the equivalent of 25 mg/m(2) intravenously. Studies also concluded a lack of food effect on the administration of oral vinorelbine. In addition, no drug-drug interactions were found with a variety of commonly used antineoplastic agents.Vinorelbine, either orally or intravenously, has been investigated in randomised phase II trials as a single agent and in combination with cisplatin or carboplatin in patients with NSCLC. In general, response and survival results with oral vinorelbine appeared similar to the intravenous agent. Adverse-effect profiles were also similar for the two formulations. Clearly, the issue of venous irritation does not exist with oral vinorelbine; however, nausea and vomiting were more frequent when vinorelbine was administered orally compared with intravenously when no planned antiemetic therapy is given.

Lack of pharmacokinetic interaction when switching from fluoxetine to milnacipran.

The lack of a therapeutic effect or unsupportable side-effects can lead to substitution of one antidepressant by another. The present study investigated potential modifications to the pharmacokinetic profile of milnacipran at steady-state when it is substituted for fluoxetine without any washout period. The open-label, multiple dose, three-period study was carried out in 12 evaluable healthy volunteers. A reference period (period 1) comprising a 3.5-day treatment with milnacipran at 50 mg b.i.d. was followed, after a 5-10-day washout, by 3 weeks of administration of 20 mg fluoxetine once daily (period 2), immediately followed by a further 3.5 days of administration of milnacipran at 50 mg b.i.d. (period 3). Blood samples collected at each period were analysed for milnacipran, N-dealkyl milnacipran, fluoxetine and norfluoxetine. Potential drug-drug interactions were evaluated by comparing milnacipran pharmacokinetic parameters between periods 1 and 3. A steady-state of fluoxetine and its metabolite was effectively reached by the end of the 3-week period. A steady-state of milnacipran was reached on day 2 of both periods 1 and 3. Trough concentrations of milnacipran were 66 and 65 ng/ml before and after the fluoxetine administration period, respectively. Cmax values were 226 and 248 ng/ml. When comparing the kinetic parameters of milnacipran before and after fluoxetine treatment, all the 90% confidence intervals were in the 20% range. No significant difference in the adverse events of milnacipran was observed before or after fluoxetine administration.

Characterization of human cytochrome P450 isoenzymes involved in the metabolism of vinorelbine.

Vinorelbine (VRL) (IV Navelbine) is a semi-synthetic vinca alkaloid, used in therapeutics for the treatment of non-small-cell lung cancer and advanced breast cancer. The aim of this study was to characterize the cytochrome P450 (CYP) isoenzymes involved in VRL metabolism. VRL was incubated at 1.28 x 10(-5) m for 90 min with human hepatic microsomes prepared from 14 donors (one woman and 13 men aged from 27 to 76 years old) and characterized for CYP1A2, CYP2D6, CYP2E1 and CYP3A4 activities. A four-combined-approach study was performed, including correlation between CYP activities and VRL metabolism among the 14 batches of microsomes, inhibition of VRL biotransformation by isoform-selective substrates and by specific inhibitory antibodies, and incubation with supersomes. Analysis of unchanged VRL and its metabolites was performed using an HPLC method coupled with both radioactive and UV detections. No correlation between CYP1A2 or CYP2E1 and VRL metabolism was observed in the 14 batches of microsomes used. A correlation was shown between VRL metabolism and CYP3A4 activity as determined with the dextromethorphan N-demethylase and nifedipine oxidase activities (r(2)=0.80 and 0.59, respectively). These results were strengthened by a correlation between the metabolism extent of VRL and CYP3A4 protein content determined by immunoblotting (r(2)=0.75). Furthermore, VRL biotransformation was inhibited by troleandomycine, the CYP3A4-specific inhibitor substrate (80% of inhibition) and by anti-CYP3A antibodies (36% of inhibition). On the contrary, a low correlation with CYP2D6 activity as determined by dextrometorphan O-demethylation (r(2)=0.31) was established. CYP2D6 supersomes did not metabolize the drug whereas 63.4% of VRL were metabolized by microsomes overexpressing CYP3A4 isoform. These data indicated that CYP3A4 is the main enzyme involved in the hepatic metabolism of VRL in human, whereas CYP2D6 is not involved.

Oral versus intravenous vinorelbine: clinical safety profile.

The availability of chemotherapeutic drugs administrable by oral route represents a step forward in the management of cancer patients. Among oral agents, vinorelbine is particularly interesting for its pharmacological characteristics and clinical efficacy. Oral vinorelbine is rapidly absorbed (1.5-3 hours) with an elimination half-life of approximately 40 hours. It shows a low level of binding to plasma proteins (13%), is highly bound to platelets (78%) and has a hepatic metabolism and an absolute bioavailability of 40% with a moderate and similar interpatient variability for the two forms. Food has no influence on the pharmacokinetic profile of oral vinorelbine even if nausea/vomiting is less frequent and less severe in the fed patients than in the fasting patients. Therefore, to ensure patient comfort, it is recommended that oral vinorelbine is administered with a snack. All the metabolites of oral vinorelbine have been identified and, among these, only deacetyl-vinorelbine presented activity demonstrating that for both oral and intravenous (i.v.) routes of administration the drug has the same metabolism pattern. Oral vinorelbine is eliminated mainly in a unconjugated form via the bile. In this process, the CYP 3A4 isoform of cytochrome P450 is mostly involved. Absorption of oral vinorelbine is not delayed in elderly patients. After oral administration, blood concentrations of vinorelbine in elderly patients are within the range of values observed in younger patients. The absolute bioavailability is close to 38% in elderly whereas it is close to 40% in younger patients. This difference is not significant. As compared to the intravenous drug, oral vinorelbine demonstrated linear pharmacokinetics as well an absolute bioavailability of approximately 40%, and a reliable dose-correspondence of 80 mg/m2 oral form --> 30 mg/m2 i.v. and 60 mg/m2 oral --> 25 mg/m2 i.v. Therefore, i.v. and oral forms show similar interindividual variability, same metabolism pattern, reproducible intra-patient blood exposure, and same pharmacokinetic-pharmacodynamic relationship. Oral vinorelbine has shown significant activity in advanced non-small cell lung cancer. Given at 60 mg/m2/week for the first 3 administrations and then increased to 80 mg/m2/week achieved the same efficacy as i.v. vinorelbine in terms of progression-free survival, overall survival, objective response. Mild-to-moderate gastrointestinal toxicity, easily manageable with standard treatment was recorded. Reproducible efficacy compared to previously reported results with vinorelbine i.v. Also, in advanced breast cancer, oral vinorelbine has shown significant activity with a good therapeutic index. Albeit no formal comparison between the oral and the intravenous formulations of vinorelbine has been made, however, the oral route seems to offer major advantages to patients who are faced with a clear decrease in the frequency of hospital admissions as compared to that needed to give intravenous chemotherapy.

Lack of interaction of milnacipran with the cytochrome p450 isoenzymes frequently involved in the metabolism of antidepressants.

OBJECTIVE: To compare the pharmacokinetics of milnacipran in extensive metabolisers (EMs) and poor metabolisers (PMs) of sparteine and mephenytoin, and to assess the influence of multiple administrations of milnacipran on the activity of cytochrome P450 (CYP) isoenzymes through its own metabolism and through various probes, namely CYP2D6 (sparteine/dextromethorphan), CYP2C19 (mephenytoin), CYP1A2 (caffeine) and CYP3A4 (endogenous 6-beta-hydroxy-cortisol excretion). METHODS: Twenty-five healthy subjects, 12 EMs for both sparteine/dextromethorphan and mephenytoin, nine EMs for mephenytoin and PMs for sparteine/dextromethorphan (PM(2D6)) and four PMs for mephenytoin and EMs for sparteine/dextromethorphan (PM(2C19)) were administered milnacipran as a single 50 mg capsule on day 1 followed by a 50 mg capsule twice daily for 7 days. The pharmacokinetics of milnacipran and its oxidative metabolites were assessed after the first dose (day 1) and after multiple administration (day 8), and were compared for differences between CYP2D6 and CYP2C19 PMs and EMs. Metabolic tests were performed before (day -2), during (days 1 and 8) and after (day 20) milnacipran administration. RESULTS: Milnacipran steady state was rapidly achieved. Metabolism was limited: approximately 50% unchanged drug, 30% as glucuronide and 20% as oxidative metabolite (mainly F2800 the N-dealkyl metabolite). Milnacipran administration to PM2D6 and PM2C19 subjects did not increase parent drug exposure or decrease metabolite exposure. Milnacipran oxidative metabolism is not mediated through CYP2D6 or CYP2C19 polymorphic pathways nor does it significantly interact with CYP1A2, CYP2C19, CYP2D6 or CYP3A4 activities. CONCLUSION: Limited reciprocal pharmacokinetic interaction between milnacipran and CYP isoenzymes would confer flexibility in the therapeutic use of the drug when combined with antidepressants. Drug-drug interaction risk would be low, even if the combined treatments were likely to inhibit CYP2D6 and CYP2C19 isoenzyme activities.

Determination of milnacipran, a serotonin and noradrenaline reuptake inhibitor, in human plasma using liquid chromatography with spectrofluorimetric detection.

Milnacipran is an antidepressant drug belonging to the class of serotonin and noradrenaline reuptake inhibitors. A sensitive high performance liquid chromatographic during the development method coupled with a fluorimetric detection was set up, validated and then used routinely of the drug. After liquid-liquid extraction, milnacipran and its internal standard were analyzed by reversed-phase liquid chromatography (LC). The drug was derivatized with fluorescamine for fluorescence detection. The identity of the liquid chromatography peaks was controlled using mass spectrometry. The assay linearity was validated up to 1000 ng/ml. The limit of quantification was set at 5 ng/ml. Precision values (relative standard deviations) were lower than 5.4%, whereas the mean accuracy was higher than 95%. The extraction recoveries were higher than 70% for both milnacipran and the internal standard. In clinics, the LC-fluorescence method was routinely used to investigate the pharmacokinetics of milnacipran in patients and proved to be robust and capable of quantifying milnacipran in plasma for at least 36 h (four- to five-fold the elimination half-life).

Pharmacokinetic linearity of i.v. vinorelbine from an intra-patient dose escalation study design.

As pharmacokinetics represents a bridge between pharmacological concentrations and clinical regimens, the pharmacokinetic exploration of the therapeutic dose range is a major outcome. This study was aimed at assessing pharmacokinetic linearity of i.v. vinorelbine through an open design with intra-patient dose escalation (3 doses/group). Three groups of six patients received either 20-25-30 mg/m2; or 25-30-35 mg/m2; or 30-35-40 mg/m2. The inclusion criteria were: histologically confirmed tumour with at least one assessable target lesion, age 25-75 years, WHO PS < or =2, normal haematology and biochemistry, life expectancy > or =3 months. The pharmacokinetics was evaluated in both whole blood and plasma over 120 h. Twenty-six patients were recruited and 18 were evaluable for pharmacokinetics. The toxicity consisted in grade < or =3 leucopenia and neutropenia (<20% of courses) and two grade 4 constipation with rapid recovery (2/54 courses). Compared to blood, plasma was demonstrated to underestimate the pharmacokinetic parameters. In blood, the drug total clearance was about 0.6 l/h/kg, with minor contribution of renal clearance, steady state volume of distribution close to 13 l/h/kg, and elimination half-life at about 40 h. A pharmacokinetic linearity was demonstrated up to 40 mg/m2, and even up to 45 mg/m2 when pooling data from another study. A pharmacokinetic-pharmacodynamic relationship was evidenced on leucopenia and neutropenia when pooling the data from the two studies.

Non-small-cell lung cancer in elderly patients: influence of age on vinorelbine oral pharmacokinetics.

The majority of cancer-related deaths are attributed to lung carcinoma. Age increases this incidence, which is also likely associated with physiologic modifications that affect drug pharmacokinetics and metabolism. Therefore, knowledge of pharmacokinetics in elderly patients is one of the major factors in deciding whether or not to reduce the dose to prevent toxicity. This phase II study was aimed at evaluating the influence of age on oral vinorelbine pharmacokinetics in elderly patients with non-small-cell lung cancer (NSCLC). Inclusion criteria were > 70 years of age; histologically or cytologically proven NSCLC; inoperable stage IIIB, IV, or delayed relapse of any stage becoming unresectable; Karnofsky performance status > 80%; and normal hematology and biochemistry. Blood-limited sampling at intervals of 1.5, 3, and 24 hours after dosing was performed during the first administration of oral vinorelbine at 60 mg/m2. Bayesian pharmacokinetic parameters were calculated through previously published nonlinear mixed-effect modeling (NONMEM), and compared with a reference population of 52 patients (age, 56 years 12) selected from vinorelbine pharmacokinetic database. There were 48 patients evaluable for pharmacokinetics out of the 52 elderly patients enrolled (age, 74 years 3). There was no difference between pharmacokinetic parameters, including the bioavailability factor evaluated by NONMEM, even without intravenous administration, and a similar interindividual variability (32%-33%) was observed between the 2 groups. Furthermore, no correlation between age (range, 31-82 years) and oral vinorelbine total clearance was observed in 100 patients pooled together. Therefore, no requirement for oral vinorelbine dose reduction was suggested from a pharmacokinetic standpoint.

A simultaneous oral/intravenous population pharmacokinetic model for vinorelbine.

OBJECTIVES: To develop a population pharmacokinetic (PK) model for simultaneous analysis of oral and intravenous data, to compare the variability between the two routes of administration of vinorelbine, to search for the main patient characteristics that explain this variability, and to estimate the mean population bioavailability of oral vinorelbine. PATIENTS AND METHODS: A PK model was developed from 175 phase I/II patients (419 courses) treated by intravenous (20-45 mg/m2) and/or oral (60-100 mg/m2) vinorelbine given as monotherapy. Oral and intravenous PK data were simultaneously fitted using the NONMEM program, allowing the estimation of oral PK parameters such as the bioavailability factor in patients who received only the oral formulation. Covariates included demographic characteristics, biological markers, hematological parameters, liver metastases, early vomiting, and food intake. The population covariate model was developed from rich sampling data ( n=187 phase I courses) and then assessed from sparse sampling data ( n=232 phase II courses). RESULTS: A three-compartment model best described the combined oral/intravenous blood concentration-time data. The mean absolute bioavailability was 36%, with moderate interindividual (CV=20%) and intraindividual (CV=19%) variability. Bayesian clearance was accurately estimated in 180 of 187 patients. The clearance of oral and intravenous vinorelbine showed comparable variability at usual doses (25-30 mg/m2 intravenous; CV=26%; 60-80 mg/m2 oral, CV=33%) and was moderately increased when including maximum tolerated doses (20-45 mg/m2 intravenous, CV=27%; 60-100 mg/m2 oral, CV=36%). Several relevant covariate relationships influencing the total body clearance of vinorelbine were independent of the route of administration: body surface area (proportional relationship), platelet count above 400 x 10(9)/l (negative correlation), creatinine clearance (positive correlation), and elevated transaminases (negative correlation). Food intake induced a lag time in the absorption of oral vinorelbine. A weak and poorly estimated relationship was observed between elevated alkaline phosphatase levels and bioavailability, although hepatic markers such as GGT, LDH, total protein, and liver metastases and age had no effect on vinorelbine pharmacokinetics. CONCLUSIONS: By means of the simultaneous analysis of oral and intravenous data the bioavailability (F=36%) and its associated variability were estimated. At usual doses similar levels of variability were observed between oral and intravenous routes. As a result of the identification of covariates from phase I data and their confirmation from phase II data further explorations based on limited sampling strategies are now possible. The use of a simultaneous oral/intravenous model allows a better characterization of the PK profile of vinorelbine after administration by either vascular or oral route

Pharmacology and pharmacokinetics of milnacipran.

Milnacipran is a dual-action antidepressant drug with equivalent inhibitory action at noradrenaline and serotonin neuronal reuptake systems. This dual action has been demonstrated in vitro and in vivo in experimental animals, and ex vivo in man. Milnacipran has no relevant affinity for any neurotransmitter receptor studied, in particular postsynaptic adrenergic, muscarinic and histamine receptors, and is therefore expected to be devoid of the prominent side-effects of many earlier antidepressants. Studies in human volunteers have not demonstrated any impact of milnacipran on cognitive function, consistent with its lack of anticholinergic properties. These pharmacodynamic properties are well preserved in vivo in humans, because milnacipran is only metabolized to a limited extent, and therefore circulates in the body principally as the unchanged parent drug, which is the only pharmacologically active compound at clinical doses. The pharmacokinetic profile of milnacipran is characterized by rapid absorption, high bioavailability, low protein binding, and rapid elimination, both by hepatic glucuronidation and renal excretion. This gives milnacipran certain pharmacokinetic advantages, such as low inter-individual variation in plasma levels, low potential for drug interactions, and limited impact on hepatic cytochrome P450 systems. These pharmacokinetic properties differentiate milnacipran from most other antidepressant drugs and contribute to the good safety profile of milnacipran and allow it to be used simply and flexibly in clinical practice.

Population pharmacokinetics model and limited sampling strategy for intravenous vinorelbine derived from phase I clinical trials.

AIMS: a) To characterize the pharmacokinetics of intravenous vinorelbine, b) to use a population analysis for the identification of patient covariates that might appreciably influence its disposition and c) to define a limited sampling strategy for further Bayesian estimation of individual pharmacokinetic parameters. METHODS: All data were collected from 64 patients (99 courses) entered in three different phase I trials that have been previously reported. All patients received vinorelbine as a 20 min infusion with dose levels ranging from 20-45 mg m-2. The population pharmacokinetic model was built in a sequential manner on a subset of two-thirds of the data, starting with a covariate-free model then progressing to a covariate model using the nonlinear-mixed effect methodology. The remaining one-third of the data were used to validate several sparse sampling designs. RESULTS: A linear three-compartment model characterized vinorelbine blood concentrations (n=1228). Two primary pharmacokinetic parameters (total clearance and volume of distribution) were related to various combinations of covariates. The relationship for total clearance (CLtotal (l h-1)=29.2xBSAx(1-0.0090 Plt)+6.7xWt/Crs) was dependent on the patient's body surface area (BSA), weight (Wt), serum creatinine (Crs) and platelet count before administration (Plt). The optimal limited sampling strategy consisted of a combination of three measured blood concentrations; the first immediately before the end of infusion or 20 min later, the second at either 1 h, 3 h or 6 h and the third at 24 h after drug administration. CONCLUSIONS: A population pharmacokinetic model and a limited sampling strategy for intravenous vinorelbine have been developed. This is the first population analysis performed on the basis of a large phase I database that has identified clinical covariates influencing the disposition of i.v. vinorelbine. The model can be used to obtain accurate Bayesian estimates of pharmacokinetic parameters in situations where extensive pharmacokinetic sampling is not feasable.