Chronic treatment with asenapine affects cytochrome P450 2D (CYP2D) in rat brain and liver. Pharmacological aspects.

Neuroleptics have to be used for a long time to produce a therapeutic effect. Cytochrome P450 2D (CYP2D) enzymes mediate alternative pathways of neurotransmitter synthesis (i.e. tyramine hydroxylation to dopamine and 5-methoxytryptamine O-demethylation to serotonin), and metabolism of neurosteroids. The aim of our present study was to examine the influence of chronic treatment with the new atypical neuroleptic asenapine on CYP2D in rat brain. In parallel, liver CYP2D was investigated for comparison. Asenapine added in vitro to microsomes of control rats competitively, but weakly inhibited the activity of CYP2D (brain: Ki = 385 µM; liver: Ki = 36 µM). However, prolonged administration of asenapine (0.3 mg/kg sc. for 2 weeks) significantly diminished the activity and protein level of CYP2D in the frontal cortex, nucleus accumbens, hippocampus and cerebellum, but did not affect the enzyme in the hypothalamus, brain stem, substantia nigra and the remainder of the brain. In contrast, asenapine enhanced the enzyme activity and protein level in the striatum. In the liver, chronically administered asenapine reduced the activity and protein level of CYP2D, and the CYP2D1 mRNA level. In conclusion, prolonged administration of asenapine alters the CYP2D expression in the brain structures and in the liver. Through affecting the CYP2D activity in the brain, asenapine may modify its pharmacological effect. By increasing the CYP2D expression/activity in the striatum, asenapine may accelerate the synthesis of dopamine (via tyramine hydroxylation) and serotonin (via 5-methoxytryptamine O-demethylation), and thus alleviate extrapyramidal symptoms. By reducing the CYP2D expression/activity in other brain structures asenapine may diminish the 21-hydroxylation of neurosteroids and thus have a beneficial influence on the symptoms of schizophrenia. In the liver, by reducing the CYP2D activity, asenapine may slow the biotransformation of concomitantly administered CYP2D substrates (drugs) during continuous treatment of schizophrenia or bipolar disorders.

Design of long acting invasomal nanovesicles for improved transdermal permeation and bioavailability of asenapine maleate for the chronic treatment of schizophrenia.

Asenapine Maleate (ASPM) is a second generation antipsychotic used for the management of schizophrenia but with very limited oral bioavailability due to its extensive first pass metabolism. Transdermal administration of ASPM using nanocarriers like invasomes might offer an excellent alternative to its oral administration with enhanced bioavailability and a sustained action. ASPM-loaded invasomes were successfully prepared by thin film hydration technique; meanwhile the penetration enhancing effect of terpenes (cineole and limonene) was compared to hydromiscible cosolvent (Transcutol®). Soft nanovesicles containing Transcutol® displayed smaller particle sizes than invasomes containing limonene and cineole while invasomes showed higher efficiency to encapsulate asenapine. Ex- vivo skin permeation revealed that invasomes with limonene are more efficient than those with cineole for the transdermal delivery of asenapine. The optimum nano-invasomes formulation contained 1% Limonene and showed particle size of 82 ± 0.6 nm, entrapment efficiency of 56.6 ± 1.5 % and transdermal flux of 3401.6 ± 604.2 (µg/h.cm2). Transmission electron microscopy of the selected formulation showed uniform spherical vesicles with intense outline and lighter core and FTIR study emphasized that ASPM was completely incorporated within the vesicles. The in- vivo pharmacokinetic study revealed that transdermal invasomes achieved 2 folds higher Cmax compared to oral suspension and delayed the Tmax from 1.5 h to around 4 h. The bioavailability of asenapine loaded invasomes after transdermal application was significantly improved to 54.5% compared to the 3.6 % achieved with the oral administration and exceeding the bioavailability of sublingual tablets currently available in the market and exhibited sustained release kinetics over 72 h which permits reduction of dosing frequency to increase patient adherence to medication.

Pharmacokinetic Profile of the Asenapine Transdermal System (HP-3070).

PURPOSE/BACKGROUND: The asenapine transdermal system (HP-3070) is the first antipsychotic patch approved in the United States for treatment of adults with schizophrenia. METHODS/PROCEDURES: Three phase 1, open-label, randomized studies characterized the pharmacokinetic (PK) profile of HP-3070 by assessing its relative bioavailability compared with sublingual asenapine, its single-/multiple-dose PK and dose proportionality, and the effects of application site, ethnicity, and external heat on bioavailability. Two studies were conducted in healthy subjects, and 1 was conducted in adults with schizophrenia. FINDINGS/RESULTS: During single HP-3070 administration, asenapine concentrations increased gradually over approximately 12 hours and remained steady until the patch was removed 24 hours after application. Asenapine area under the curve values at HP-3070 3.8 and 7.6 mg/24 hours doses were similar to those for sublingual asenapine 5 and 10 mg twice-daily doses, respectively, whereas peak exposure (maximum observed plasma concentration) was significantly lower. During daily application of HP-3070, steady-state PK was reached within approximately 72 hours after initiating daily dosing and was characterized by peak-to-trough asenapine plasma concentration ratio of approximately 1.5. HP-3070 PK was dose proportional in the dose range studied, not affected by administration site, and similar across the studied ethnic groups. Application of external heat increased the rate of asenapine absorption (time to reach maximum observed plasma concentration) but did not significantly affect peak and total exposure. IMPLICATIONS/CONCLUSIONS: HP-3070 exhibited a dose-dependent PK profile unaffected by site of administration or ethnicity. HP-3070 showed a predictable absorption profile with limited variability, with an area under the curve similar to that of sublingual asenapine. Based on these PK metrics, HP-3070 steadily delivers asenapine with lower peaks and troughs than sublingual administration of asenapine.

A Novel Cryptococcal Meningitis Therapy: The Combination of Amphotericin B and Posaconazole Promotes the Distribution of Amphotericin B in the Brain Tissue.

The deficient brain tissue distribution of amphotericin B (AMPB) seriously restricts its treatment for the clinical efficacy of cryptococcus neoformans meningitis (CNM). We strive to develop a tactic to increase its concentration in brain tissue. We aimed to investigate whether the combination of AMPB and posaconazole (POS) could be more effective in the treatment of CNM and to elucidate its potential mechanisms. HPLC analysis was used to analyze the concentration of AMPB in mouse serum, brain tissue, and BCECs cells. Schrodinger molecular docking, in vitro plasma balance dialysis, and ultrafiltration analysis were performed to evaluate the combinative effect of AMPB and POS with serum albumin and POS on AMPB plasma protein binding. H&E staining and colonization culture experiment of CN were employed to assess the effect of POS on the efficacy of AMPB. POS + AMPB significantly reduced the concentration of plasma total AMPB and increased its concentration in the brain tissue. However, the P-gp inhibitor zosuquidar, BCRP inhibitor Ko143, and a common inhibitor of both, elacridar, had no significant effect on its concentration. Molecular docking, balance dialysis, and ultrafiltration analysis showed that AMPB and POS had potential binding properties to serum albumin. Meanwhile, 4 and 8 µg/mL POS could significantly increase the concentration of free AMPB in plasma. POS and three inhibitors all had no significant effect on the uptake of AMPB by BCECs, but serum albumin had. The therapeutic effect of CNM in mice was confirmed that AMPB and AMPB+POS could restrain the infiltration of neutrophils and lymphocytes in cortical neurons and improve the bleeding and markedly inhibit the proliferation of CN. Collectively, we propose that POS competitively binds to the plasma protein sites of AMPB, thereby increasing its level in the brain tissue. Meanwhile, POS could enhance the efficacy of AMPB in the treatment of CNM, which may be independent of P-gp and BCRP proteins.

Efficacy and Safety of HP-3070, an Asenapine Transdermal System, in Patients With Schizophrenia: A Phase 3, Randomized, Placebo-Controlled Study.

OBJECTIVE: Asenapine is a second-generation antipsychotic used to treat individuals with schizophrenia. This phase 3 study assessed efficacy and safety of HP-3070, an asenapine transdermal system (patch), in adults with schizophrenia. METHODS: In this inpatient study, a 3- to 14-day screening/single-blind run-in washout period was followed by a 6-week double-blind period wherein patients with acutely exacerbated schizophrenia (DSM-5 criteria) were randomized 1:1:1 and received HP-3070 7.6 mg/24 h (n = 204), HP-3070 3.8 mg/24 h (n = 204), or placebo (n = 206). Primary endpoint was change from baseline (CFB) in week 6 Positive and Negative Syndrome Scale (PANSS) total score versus placebo; key secondary endpoint was CFB in week 6 Clinical Global Impression-Severity of Illness score versus placebo. Safety endpoints included treatment-emergent adverse events (TEAEs) and dermal assessments. RESULTS: Each of the HP-3070 doses demonstrated significant improvement versus placebo at week 6 for the primary and key secondary endpoints. Differences in the least-squares mean (LSM) (95% CI; adjusted P) of CFB for PANSS total scores were -4.8 (-8.06 to -1.64; adjusted P = .003) and -6.6 (-9.81 to -3.40; adjusted P < .001) for 7.6 mg/24 h and 3.8 mg/24 h, respectively. HP-3070 was well tolerated, with a systemic safety profile consistent with sublingual asenapine. Incidence of application site TEAEs was higher for HP-3070 (14.2%, 7.6 mg/24 h; 15.2%, 3.8 mg/24 h) versus placebo (4.4%). Discontinuations due to application site reactions or skin disorders (urticaria, pruritus) were infrequent (≤ 0.5% per treatment group). CONCLUSIONS: HP-3070 7.6 mg/24 h and 3.8 mg/24 h doses were efficacious and well tolerated. As the first transdermal antipsychotic patch available in the US, HP-3070 offers a novel treatment option for people with schizophrenia. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT02876900; EudraCT number: 2015-005134-21.

Surface-engineered nanoliposomes with lipidated and non-lipidated peptide-dendrimeric scaffold for efficient transdermal delivery of a therapeutic agent: Development, characterization, toxicological and preclinical performance analyses.

The current study aimed to develop novel peptide dendrimer (PD)-conjugated nanoliposomal formulations of asenapine maleate (ASP) for improvement in the transdermal delivery and pharmacokinetic profile of the drug. Novel arginine-terminated PDs (+/-lipidation) were prepared by solid phase peptide synthesis, followed by conjugation onto ASP nanoliposomes. The nanoliposomes were characterized for particle size (and polydispersity index), zeta potential (ZP), drug entrapment efficiency, shape and morphology, differential scanning calorimetry and FT-IR spectroscopy. Ex vivo skin permeation and retention studies demonstrated considerably higher percutaneous permeation of ASP from the developed nanoliposomes (Q24 = 794.31 ± 54.89 µg/cm2, Jss = 105.40 ± 4.8 µg/cm2/h, ER = 36.85 ± 2.89 for liposomes with lipidated peptide dendrimer (Lipo-PD2)) in comparison with passive diffusion studies (Q24 = 63.09 ± 3.56 µg/cm2, Jss = 3.01 ± 0.23 µg/cm2/h). Confocal Laser Scanning Microscopy (CLSM) confirmed the higher percutaneous penetration of Lipo-PD2 in comparison with liposomes without the dendrimer. In vitro cytotoxicity determined on HaCaT cell line demonstrated CTC50 of >1000 µg/mL for both the synthesized PDs and Lipo-PD2. Pharmacokinetic studies in male Sprague Dawley rats revealed considerably and significantly higher t1/2 = 82.32 ± 14.48 h and AUC0-t = 4403.34 ± 367.10 h.ng/mL, from the developed formulation, compared to orally administered ASP (t1/2 = 21.64 ± 2.53 h and AUC0-t = 2303.55 ± 444.5 h.ng/mL), demonstrating higher bioavailability and longer retention in vivo. Additionally, in vivo skin retention, brain uptake studies and pharmacodynamics of the developed formulations were investigated. Stability studies indicated that the formulations were stable up to relatively stable with respect to size, ZP and drug content for 4 months at the tested conditions. This study demonstrates that the developed PD-conjugated nanoliposomal formulations can effectively serve as a transdermal delivery strategy for ASP.

Long-term sustained release Poly(lactic-co-glycolic acid) microspheres of asenapine maleate with improved bioavailability for chronic neuropsychiatric diseases.

Schizophrenia and bipolar disorder are severe chronic neuropsychiatric diseases, affecting hundreds of millions of people worldwide. Asenapine maleate (ASM) has been demonstrated as a safe and effective therapeutic agent under twice-daily administration. However, lower compliance is observed when patients are treated with ASM, which significantly limits its application in schizophrenia and bipolar disorder. Moreover, the low bioavailability of ASM caused by first-pass metabolism and poor aqueous solubility also impairs the treatment effect. A formulation of ASM with the property of long-term sustained release and improved bioavailability can be a solution to overcome these weaknesses. In this article, we prepared ASM-loaded poly(lactic-co-glycolic acid) (ASM-PLGA) microspheres through different techniques, including emulsification-solvent evaporation (ESE), Shirasu porous glass membrane emulsification (SPG-ME), and microfluidic method. In vitro and in vivo assessments demonstrated that uniform-sized microspheres generated by the microfluidic process sustainably released ASM throughout 40-days, showing low burst release and significantly improved bioavailability. The results suggest that ASM-PLGA microspheres prepared by the microfluidic method provide an efficient strategy to enhance the drug exposure of ASM as the treatment of chronic neuropsychiatric diseases. It is also evident that this microfluidic strategy has the potential to construct with other drugs, establishing long-acting formulations.

High-dose etoposide formulations do not saturate intestinal P-glycoprotein: Development, stability, and pharmacokinetics in Sprague-Dawley rats.

It has been suggested that oral absorption of low-permeable P-glycoprotein (P-gp) substrates can be increased through saturation of P-gp. For BCS class IV drug substances, saturating P-gp is challenging due to low aqueous solubility. The present study investigated if the BCS IV drug substance etoposide could be solubilized to a concentration saturating P-gp after oral administration. A formulation consisting of 10% (w/v) of pluronic® F-127 and polyvinylpyrrolidone/vinyl acetate (PVP/VA), and 57% (v/v) ethanol enhanced etoposide's solubility approximately 100 times (16 mg mL-1) compared to its aqueous solubility. In vitro, this formulation was stable upon dilution in simulated intestinal fluid. In male Sprague-Dawley rats, oral administration of increasing solubilized etoposide doses using the formulation matrix increased the AUC0-∞ of etoposide dose-proportionally but resulted in a lower absolute oral bioavailability (F) and rate of absorption as compared to control. At the highest investigated dose (100 mg kg-1), AUC0-∞ and Cmax were significantly increased by 2.9- and 1.4-fold, respectively, compared to control dosed at 20 mg kg-1. A single oral dose of 20 mg kg-1 zosuquidar followed by 20 mg kg-1 oral etoposide increased F 8.6-fold. In conclusion, a stable formulation with improved etoposide solubility was developed, yet the formulation did not result in increased oral bioavailability of etoposide.

Spinal inhibition of p38 MAP kinase reduces inflammatory and neuropathic pain in male but not female mice: Sex-dependent microglial signaling in the spinal cord.

Previous studies have shown that activation of p38 mitogen-activating kinase (MAPK) in spinal microglia participates in the generation of inflammatory and neuropathic pain in various rodent models. However, these studies focused on male mice to avoid confounding effects of the estrous cycle of females. Recent studies have shown that some spinal pro-inflammatory signaling such as Toll-like receptor 4-mediated signaling contributes to pain hypersensitivity only in male mice. In this study we investigated the distinct role of spinal p38 in inflammatory and neuropathic pain using a highly selective p38 inhibitor skepinone. Intrathecal injection of skepinone prevented formalin induced inflammatory pain in male but not female mice. Furthermore, intrathecal skepinone reduced chronic constriction injury (CCI) induced neuropathic pain (mechanical allodynia) in male mice on CCI-day 7 but not CCI-day 21. This male-dependent inhibition of neuropathic pain also occurred in rats following intrathecal skepinone. Nerve injury induced spinal p38 activation (phosphorylation) in CX3CR1-GFP(+) microglia on CCI-day 7, and this activation was more prominent in male mice. In contrast, CCI induced comparable microgliosis and expression of the microglial markers CX3CR1 and IBA-1 in both sexes. Notably, intraperitoneal or local perineural administration of skepinone inhibited CCI-induced mechanical allodynia in both sexes of mice. Finally, skepinone only reduced the frequency of spontaneous excitatory postsynaptic currents (sEPSCs) in lamina IIo neurons of spinal cord slices of males 7days post CCI. Therefore, the sex-specific p38 activation and signaling is confined to the spinal cord in inflammatory and neuropathic pain conditions.

An in vivo microdialysis study of FLZ penetration through the blood-brain barrier in normal and 6-hydroxydopamine induced Parkinson's disease model rats.

FLZ (N-[2-(4-hydroxy-phenyl)-ethyl]-2-(2,5-dimethoxy-phenyl)-3-(3-methoxy-4-hydroxy-phenyl)-acrylamide) is a novel synthetic squamosamide derivative and a potential anti-Parkinson's disease (PD) agent. The objective of the present study was to investigate the penetration of free FLZ across the BBB and the effects of P-gp inhibition on FLZ transport in normal and 6-hydroxydopamine (6-OHDA) induced PD model rats. In vivo microdialysis was used to collect FLZ containing brain and blood dialysates following intravenous (i.v.) drug administration either with or without pretreatment with the specific P-gp inhibitor, zosuquidar trihydrochloride (zosuquidar·3HCl). A sensitive, rapid, and reliable ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) technique was developed and validated to quantitate free FLZ levels in the dialysates. No significant differences were observed in the brain/blood FLZ area under the concentration-time curve (AUC) ratio between normal and PD model rats. However, pretreatment with zosuquidar·3HCl markedly increased the AUC ratio in both rat models. In addition, FLZ penetration was similar in zosuquidar·3HCl-pretreated normal and PD rats. These results suggest that P-gp inhibition increases BBB permeability to FLZ, thereby supporting the hypothesis that P-gp normally restricts FLZ transfer to the brain. These findings could provide reference data for future clinical trials and may aid investigation of the BBB permeability of other CNS-active substances.

Amineptine treatment of persistent catatonic symptoms in schizophrenia: a controlled study.

BACKGROUND: Data on the treatment response of enduring catatonic phenomena accompanying chronic schizophrenia are few and far between. The aim of this study was to explore the therapeutic effects of add-on amineptine, a dopamine agonist antidepressant in chronic catatonia occurring in schizophrenia. METHOD: Fifteen subjects with DSM-IV schizophrenia presenting with persistent catatonic features underwent a 15-week, double-blind, placebo-controlled cross-over trial; they were treated for 6 weeks each with amineptine and a placebo, with a 3-week wash-out period in between. The primary outcome measures were the sum scores of the Bush-Francis Catatonia Rating Scale and the Modified Rogers Scale. Changes in other aspects of psychopathology and extrapyramidal side effects (EPS) constituted the secondary outcome measures. RESULTS: Amineptine augmentation of antipsychotic treatment had no appreciable effect on either of the catatonia ratings. Apart from a statistically significant but clinically negligible improvement in the negative symptom scores, there were no changes in the psychopathology and EPS ratings. CONCLUSION: The lack of a therapeutic effect of the dopamine agonist amineptine on persistent catatonic signs and symptoms suggests that the dopamine system may not have a decisive role in the pathophysiology of chronic catatonic syndrome arising in the context of schizophrenia.

A randomized, placebo-controlled, double-blind phase 2 study of docetaxel compared to docetaxel plus zosuquidar (LY335979) in women with metastatic or locally recurrent breast cancer who have received one prior chemotherapy regimen.

PURPOSE: To determine if concomitant administration of docetaxel plus zosuquidar.3HC1 can prolong progression-free survival in patients with metastatic breast cancer. METHODS: A randomized, double-blind, multicenter, placebo-controlled clinical trial comparing docetaxel plus 500 mg zosuquidar.3HCl (DZ) with docetaxel plus placebo (DP). RESULTS: A total of 170 patients were enrolled and randomly assigned to treatment. The median age was 53 years (range, 31-74 years). 81.7% of patients had prior chemotherapy in the adjuvant setting and 18.3% in the neoadjuvant setting. The median progression-free survival time was statistically different between groups [7.2 months (DZ) vs. 8.3 months (DP)]. Once the stratification factor relative to progression following prior chemotherapy was considered, no significant treatment difference existed. CONCLUSION: The combination of zosuquidar.3HCl plus docetaxel is safe. The analysis of efficacy data is complex, but it can be concluded that there is no difference in progression-free survival, overall survival, or response rate in the study as a whole.

A phase I trial of continuous infusion of the multidrug resistance inhibitor zosuquidar with daunorubicin and cytarabine in acute myeloid leukemia.

Zosuquidar is a potent and specific inhibitor of P-glycoprotein (P-gp). In preliminary experiments, blockade of P-gp for at least 12 h was required to reverse daunorubicin resistance. Because of the short half-life of zosuquidar, we performed a phase I trial of this drug as a 72-h infusion (CIV) in 16 patients during leukemic induction with daunorubicin and cytarabine. Study goals were to establish safety and determine the dose required for P-gp inhibition in NK cells and AML blasts. > 90% P-gp inhibition was achieved within 2h at a plasma threshold of 132 ng/ml zosuquidar. The recommended phase II dose of zosuquidar is 700 mg/day.

Leukemic blast and natural killer cell P-glycoprotein function and inhibition in a clinical trial of zosuquidar infusion in acute myeloid leukemia.

A bioassay was developed to assess P-glycoprotein (P-gp) function of peripheral blood natural killer (NK) cells and AML blasts during zosuquidar infusion. Cells were incubated with the fluorescent dye DiOC(2)(3) in the presence and absence of zosuquidar, and dye accumulation measured by flow cytometry. The assay performance was assessed using NK cells and the P-gp-positive K562/R7 cell line, and then utilized to determine the function of P-gp and its inhibition by zosuquidar in AML blasts and NK cells from patients enrolled in a Phase I trial. The assay of zosuquidar-inhibitable accumulation of DiOC(2) is robust and reproducible.

Role of xenobiotic efflux transporters in resistance to vincristine.

This study characterized interactions between efflux transporters (P-glycoprotein (MDR1) and multidrug resistance associated proteins (MRPs1-3)) and vincristine (VCR), using cell lines with differential transporter expression, and studied effects of P-glycoprotein inhibition on VCR transport and toxicity. Caco2 (express MDR1, MRPs 1-3), LS174T (express MDR1, MRPs 1, 3), and A549 (express MRPs 1-3) cells were used. To study VCR transport (effective permeability, P(eff)), VCR (1-500 nM) was added to the donor chambers of permeable supports containing Caco2 monolayers, and receiving chamber concentrations were measured. Cytotoxicity experiments were conducted with escalating concentrations of VCR in all cell lines. To determine the contribution of MDR1, experiments were also conducted with LY335979, a specific MDR1 inhibitor. VCR P(eff) was 2 x 10(-6)cm/s in Caco2 cells. LY335979 increased P(eff) in a dose dependent manner (up to 7-fold with 1 microM LY335979) in Caco2 cells. Caco2 and LS174T cell viability decreased significantly when co-incubated with both VCR and LY335979 (1 microM) (P<0.05), however this was not observed in A549 cells. In summary, MDR1 plays an important role in VCR efflux; MDR1 inhibition increased VCR P(eff) in Caco2 cells, and increased VCR cytotoxicity in Caco2 and LS174T cells (both express MDR1), but not A549 cells (minimal MDR1 expression). Inhibition of MDR1 may be a viable strategy to overcome VCR resistance in tumors expressing MDR1, however the presence of other efflux transporters should also be considered, as this will influence the success of such strategies.

Phase I study of the multidrug resistance inhibitor zosuquidar administered in combination with vinorelbine in patients with advanced solid tumours.

BACKGROUND: Zosuquidar (LY335979) is an oral P-glycoprotein modulator. This phase I study was designed to determine the maximum tolerated dose (MTD) of zosuquidar in combination with vinorelbine. The effects of zosuquidar on vinorelbine pharmacokinetics were also examined. DESIGN: Patients with advanced solid tumours were treated with escalating doses of zosuquidar administered every 8-12 h on days 7-9 and 14-16 during cycle 1 then days 0-2, 7-9, and 14-16 from cycle 2 onwards, with vinorelbine 22.5-30 mg/m2 IV on days 1, 8 and 15 every 28 days. RESULTS: Of 21 patients registered, 19 were treated at four dose levels (zosuquidar 100-300 mg/m2). Two patients had prolonged and febrile neutropenia at the second dose level resulting in a reduction of the dose of vinorelbine in subsequent dose levels. There was another patient with dose-limiting febrile neutropenia at dose level four which resulted in the expansion of the dose level three. Eight patients had stable disease and no objective responses were seen. Vinorelbine pharmacokinetic studies showed reduced clearance when given with zosuquidar. CONCLUSIONS: The MTD was zosuquidar 300 mg/m2 orally every 12 h for 3 days weekly for 3 weeks with vinorelbine 22.5 mg/m2 IV weekly for 3 weeks every 28 days. Zosuquidar may inhibit vinorelbine clearance to a modest degree.

Phase I study of docetaxel in combination with the P-glycoprotein inhibitor, zosuquidar, in resistant malignancies.

PURPOSE: To determine the maximum tolerated dose, dose-limiting toxicity, and pharmacokinetics of docetaxel infused over 1 hour when given in combination with oral zosuquidar to patients with resistant solid tumors. EXPERIMENTAL DESIGN: In cycle 1, patients received docetaxel alone. In subsequent cycles, zosuquidar was administered with docetaxel, which was escalated from 75 to 100 mg/m2. Zosuquidar was escalated from 100 to 300 mg/m2 every 8 hours on days 1 to 3 for a total of 7 doses, or from 400 to 500 mg every 12 hours for 2 doses administered 2 hours before docetaxel. The pharmacokinetics of docetaxel with and without zosuquidar administration were obtained. RESULTS: Thirty-six of 41 patients completed at least one cycle of docetaxel and zosuquidar. The maximum tolerated dose was docetaxel 100 mg/m2 and zosuquidar 500 mg every 12 hours for 2 doses. The most common toxicity was neutropenia. In 35 patients, zosuquidar produced minimal increases in the docetaxel peak plasma concentrations and area under the curve. Dosing over 3 days with zosuquidar (7 doses) did not show benefit over the 1-day dosing. Of the 36 patients, one patient had a partial response, and 14 patients had disease stabilization. CONCLUSIONS: Docetaxel at 75 or 100 mg/m2 and zosuquidar 500 mg 2 hours before docetaxel and 12 hours later is well tolerated. Zosuquidar minimally alters the pharmacokinetics of docetaxel, allowing full dose docetaxel to be given with this P-glycoprotein modulator. A Phase II study with this combination in advanced breast carcinoma is underway.

Clinical effects and P-glycoprotein inhibition in patients with acute myeloid leukemia treated with zosuquidar trihydrochloride, daunorubicin and cytarabine.

BACKGROUND AND OBJECTIVES: P-glycoprotein (P-gp) is a major cause of multidrug resistance (MDR) in acute myelogenous leukemia (AML) and is thought to contribute to the failure of chemotherapy. Zosuquidar trihydochloride (Z.3HCL) is a potent and selective inhibitor of P-gp which rapidly and effectively inhibits drug efflux. DESIGN AND METHODS: The aim of this study was to evaluate the clinical effects of Z.3HCL and determine its influence on P-gp activity. Sixteen AML patients were entered into a phase 1 dose ranging clinical trial of Z.3HCL, co-administered intravenously with daunorubicin and cytosine arabinoside (ARA-C). Clinical outcomes, toxicity abd adverse events were assessed. P-gp function was analyzed by flow cytometry. In vitro cytotoxicity was studied using the MTT assay. RESULTS: Eleven patients achieved a complete remission and one a partial remission with a median survival of 559 (range 38-906) days. Non-hematologic grade 3 and 4 toxicities were seen in 4 patients. Z.3HCL infusion was associated with rapid inhibition of Rh123 efflux in CD56+ cells in 16/16 patients and in CD33+ cells from 6/10 patients. The median inhibition was 95% for CD56+ cells and 85.25% for CD33+ cells was significantly elevated in 6/16 patients. The median IC50, using a MTT assay for daunorubicin, decreased significantly between Z.3HCL modulated and unmodulated cells (n=11,153 and 247 ng/mL respectively, p=0.01). INTERPRETATION AND CONCLUSIONS: The modulator Z.3HCL is a specific inhibitor of P-gp efflux and can be given safely to patients with AML in combination with induction doses of conventional cytotoxic drugs.

A Phase I trial of a potent P-glycoprotein inhibitor, zosuquidar trihydrochloride (LY335979), administered intravenously in combination with doxorubicin in patients with advanced malignancy.

PURPOSE: Our intention was to (a) to investigate the safety and tolerability of a potent P-glycoprotein modulator, zosuquidar trihydrochloride (LY335979), when administered i.v. alone or in combination with doxorubicin, (b) to determine the pharmacokinetics of zosuquidar and correlate exposure to inhibition of P-glycoprotein function in a surrogate assay, and (c) to compare the pharmacokinetics of doxorubicin in the presence and absence of zosuquidar. PATIENTS AND METHODS: Patients with advanced malignancies who provided written informed consent received zosuquidar and doxorubicin administered separately during the first cycle of therapy and then concurrently in subsequent cycles. Zosuquidar was given i.v. over 48 h in a cohort-dose escalation manner until the occurrence of dose-limiting toxicity or protocol specified maximum exposure. Doxorubicin doses of 45, 60, 75 mg/m(2) were administered during the course of the trial. RESULTS: Dose escalation proceeded through 9 cohorts with a total of 40 patients. The maximal doses administered were 640 mg/m(2) of zosuquidar and 75 mg/m(2) of doxorubicin. No dose-limiting toxicity of zosuquidar was observed. Pharmacokinetic analysis revealed that, in the presence of zosuquidar at doses that exceeded 500 mg, there was a modest decrease in clearance (17-22%) and modest increase in area under the curve (15-25%) of doxorubicin. This change was associated with an enhanced leukopenia and thrombocytopenia but was without demonstrable clinical significance. The higher doses of zosuquidar were associated with maximal P-glycoprotein inhibition in natural killer cells. CONCLUSION: Zosuquidar can be safely coadministered with doxorubicin using a 48 h i.v. dosing schedule.

A population pharmacokinetic model for doxorubicin and doxorubicinol in the presence of a novel MDR modulator, zosuquidar trihydrochloride (LY335979).

PURPOSE: To develop a population pharmacokinetic model for doxorubicin and doxorubicinol in the presence of zosuquidar.3HCl, a potent P-glycoprotein inhibitor. METHODS: The population approach was used (implemented with NONMEM) to analyse doxorubicin-doxorubicinol pharmacokinetic data from 40 patients who had received zosuquidar.3HCl and doxorubicin intravenously (separately in cycle 1 and concomitantly in cycle 2 over 48 h and 0.5 h, respectively). RESULTS: A five-compartment pharmacokinetic model (including three compartments for doxorubicin pharmacokinetics with two pathways for doxorubicinol formation) best described the doxorubicin-doxorubicinol pharmacokinetics in the presence of zosuquidar.3HCl. Doxorubicin clearance (CL), peripheral volume of distribution (V2) and doxorubicinol apparent clearance (CLm/fm) and apparent volume of distribution (Vm/fm) were 62.3 l/h, 2360 l, 143 l/h and 3150 l, respectively, in the absence or presence of low doses of zosuquidar.3HCl (<500 mg). In the presence of high doses of zosuquidar.3HCl (>or=500 mg), these values decreased by 25%, 26%, 48% and 73%, respectively, and doxorubicinol pharmacokinetics were characterized by a delayed t(max) (24 h versus 4 h), which led to the inclusion of the parallel pathways. A decrease in the objective function ( P<0.005) was observed when the impact of zosuquidar.3HCl was accounted for. CONCLUSIONS: This integrated parent-metabolite population pharmacokinetic model accurately characterized the increase in doxorubicin and doxorubicinol exposure (1.33- and 2-fold, respectively) in the presence of zosuquidar.3HCl (>or=500 mg) and provided insights into the pharmacokinetic interaction, which may be useful in designing future clinical trials.