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.

Zosuquidar, a novel modulator of P-glycoprotein, does not improve the outcome of older patients with newly diagnosed acute myeloid leukemia: a randomized, placebo-controlled trial of the Eastern Cooperative Oncology Group 3999.

Zosuquidar, which modulates P-glycoprotein (P-gp) with minimal delay of anthracycline clearance, may reverse P-gp-mediated resistance in acute myeloid leukemia without increased toxicity. A total of 449 adults older than 60 years with acute myeloid leukemia or high-risk myelodysplastic syndrome enrolled in a randomized placebo-controlled double-blind trial (Eastern Cooperative Oncology Group 3999). Overall survival was compared between patients receiving conventional-dose cytarabine and daunorubicin and either zosuquidar (550 mg; 212 patients) or placebo (221 patients). Median and 2-year overall survival values were 7.2 months and 20% on zosuquidar and 9.4 months and 23% on placebo, respectively (P = .281). Remission rate was 51.9% on zosuquidar and 48.9% on placebo. All cause mortality to day 42 was not different (zosuquidar 22.2% vs placebo 16.3%; P = .158). In vitro modulation of P-gp activity by zosuquidar and expression of P-gp, multidrug resistance-related protein 1, lung resistance protein, and breast cancer resistance protein, were comparable in the 2 arms. Poor-risk cytogenetics were more common in P-gp(+) patients. P-gp expression and cytogenetics were correlated, though independent prognostic factors. We conclude that zosuquidar did not improve outcome in older acute myeloid leukemia, in part, because of the presence P-gp independent mechanisms of resistance. This trial is registered at www.clinicaltrials.gov as #NCT00046930.

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.

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.

The noncompetitive N-methyl-D-aspartate receptor antagonist, MK-801 profoundly reduces volatile anesthetic requirements in rabbits.

Rabbits anesthetized with volatile anesthetics were given bolus doses of the n-methyl-D-aspartate (NMDA) receptor antagonist MK-801. Following observation and recording of the hemodynamic and electroencephalographic effects of MK-801, the animals were tested for requirements of volatile anesthetic to prevent movement to a noxious stimulus. It was demonstrated that MK-801 significantly reduced anesthetic requirements in a dose-dependent manner, while also affecting hemodynamics and the electroencephalogram in a manner consistent with the production of a deeper plane of anesthesia.

Population pharmacokinetic model for daunorubicin and daunorubicinol coadministered with zosuquidar.3HCl (LY335979).

PURPOSE: The impact of zosuquidar.3HCl, an inhibitor of P-glycoprotein, on the pharmacokinetics of daunorubicin and daunorubicinol was examined in a phase I trial using a population approach. Pharmacokinetic and pharmacodynamic properties of zosuquidar.3HCl were also determined. METHODS: The pharmacokinetics of daunorubicin and daunorubicinol were studied following daunorubicin administration on day 1 (50 mg/m2 i.v. infusion over 10 min) alone and on day 3 concomitantly with zosuquidar.3HCl (i.v. 200 or 300 mg/m2 over 6 h or 400 mg over 3 h). Of a total of 18 patients entered, 16 with acute leukemia completed the study. RESULTS: A three-compartment pharmacokinetic model adequately described daunorubicin concentration-time profiles. Five- and four-compartment models adequately described the daunorubicin-daunorubicinol pharmacokinetics in the absence and presence of zosuquidar.3HCl, respectively. The impact of zosuquidar.3HCl on coadministered daunorubicin was minimal, with a 10% reduction in daunorubicin clearance. The model predicted a 50% decrease in daunorubicinol apparent clearance in the presence of zosuquidar.3HCl. A direct concentration-effect relationship between zosuquidar.3HCl concentrations and inhibition of rhodamine 123 (Rh123) efflux in CD56 lymphocytes was defined by a sigmoid E(max) model. The IC(50) was 31.7 microg/l. The zosuquidar.3HCl dosing regimen led to concentrations in excess of the IC(90) (169.6 microg/l) and provided maximal P-glycoprotein inhibition during the distribution phases of daunorubicin. CONCLUSIONS: The decrease in daunorubicin and daunorubicinol clearance in the presence of zosuquidar.3HCl likely reflects inhibition of P-glycoprotein in the bile canaliculi impeding their biliary excretion. The results need to be interpreted carefully due to the sequential nature of daunorubicin administration and analysis.

Pharmacological characterization of LY335979: a potent cyclopropyldibenzosuberane modulator of P-glycoprotein.

The above data indicate that LY335979 displays the following characteristics of an 'ideal modulator' of Pgp-mediated multidrug resistance: high affinity binding to Pgp, high potency for in vitro reversal of drug resistance, high therapeutic index (activity was demonstrated at doses ranging from 1-30 mg/kg) observed in in vivo antitumor efficacy experiments, and a lack of pharmacokinetic interactions that alter the plasma concentration of coadministered oncolytic agents. These desirable features strongly suggest that LY335979 is an exciting new clinical agent to test the hypothesis that inhibition of P-glycoprotein activity will result in reversal of multidrug resistance in human tumors.

[3H]MK-801 binding in Alzheimer's disease.

The density of [3H]MK-801 binding sites was studied in homogenates prepared from different cortical regions of postmortem brains of Alzheimer patients and age matched controls. Highest number of binding sites for this noncompetitive antagonist of the N-methyl-D-aspartate (NMDA) receptor was in temporal pole (Brodmann area A-38) in both groups. There were no consistent differences between patients and controls in either binding density or affinity constant in any of the areas studied. Involvement of glutamatergic neurotransmission in Alzheimer's disease does not seem to be at the level of the MK-801 recognition site on the NMDA receptor complex.

Experimental neoplastic spinal cord compression: effect of anti-inflammatory agents and glutamate receptor antagonists on vascular permeability.

It has been demonstrated in paraplegic rats harboring an epidural neoplasm that an antiedema effect can be achieved by in vivo treatment with either steroidal or nonsteroidal anti-inflammatory agents or by glutamate receptor antagonists. The effect of these treatments on vascular permeability of the normal and compressed spinal cord was quantitated by the Evans blue dye technique. Tumor-free and tumor-bearing rats were assigned randomly for treatment as follows: 0.5 ml of saline or three doses at 12-hour intervals of either dexamethasone (5 mg/kg), methylprednisolone (30 mg/kg), indomethacin (5 mg/kg every 24 hours), or a single dose of either ketamine (110 mg/kg) or MK-801 (3 mg/kg). Treatment was given at the onset of paraplegia, and the animals were killed after 30 hours. In tumor-bearing rats in the early symptomatic stage, extravasation of Evans blue dye was 4.8 times greater than that of the normal cord (P less than 0.001) and at the onset of paraplegia it was 9.9 times greater (P less than 0.0006). Glucocorticoids and indomethacin reduced dye extravasation in paraplegic animals (P less than 0.01 and P less than 0.003, respectively), but the decreased permeability induced by ketamine and MK-801 did not reach the level of significance. In tumor-free control animals permeability was not changed by administration of either glucocorticoids or indomethacin but was significantly reduced by ketamine or MK-801 (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Single-dose pharmacokinetics of amineptine and of its main metabolite in healthy young adults.

The pharmacokinetics of the tricyclic antidepressant amineptine (Survector) and its main metabolite were studied in 12 young healthy adults (6 men, 6 women; mean age 35.8 yr). Plasma samples were taken over 24 h following a single oral dose of 100 mg amineptine chloryhdrate. Plasma levels of both compounds were determined by means of high performance liquid chromatography. Amineptine was rapidly absorbed. Mean peak plasma concentrations of amineptine and its metabolite occurred 1 h and 1.5 h, respectively, after product administration. The mean apparent volume of distribution was large: 2.4 l.kg-1. Elimination was rapid; the mean half-lives of the 2 compounds were short: 0.8 h for amineptine and 2.5 h for the metabolite. The mean apparent plasma clearance of amineptine was high (124.8 l.h-1). When the results were adjusted for body weight and surface area, no significant difference in pharmacokinetic parameters was found between men and women. Given its pharmacokinetic characteristics there is no risk of amineptine accumulation and thus it is a particularly easy drug to manage. A standard dosage of amineptine was defined for use in healthy young adults.

Pharmacokinetics of amineptine after single-dose, repeated treatment and study of the at-risk populations.

In this paper, three different studies are discussed. First, pharmacokinetics of the tricyclic antidepressant amineptine (Survector) and its main metabolite were investigated in young healthy adults. Amineptine was rapidly absorbed. Mean peak plasma concentrations of amineptine and its metabolite occurred 1 and 1.5 h, respectively, after drug administration. The mean apparent volume of distribution was large: 2.4 L/kg. Elimination was rapid. T 1/2 (half-life) was 0.8 h for amineptine and 2.5 h for the metabolite. The mean apparent plasma clearance of amineptine was high (124.8 L/h). In a second study in young patients, no change in pharmacokinetic parameters was observed after a 10-day course of repeated treatment with the drug. Finally, pharmacokinetics of amineptine and its main metabolite were studied in elderly patients on day 1 and after a repeated administration for 15 days. There was no significant age-linked change in the pharmacokinetics of amineptine even if half-life and area under the curve of the metabolite were all greater in the elderly subjects than in young adults. Pharmacokinetic parameters of amineptine and its metabolite were not affected by repeated administration over 15 days. The pharmacokinetic characteristics of amineptine in elderly subjects do not necessitate any dosage alteration for this population.

Bioanalysis of zosuquidar trihydrochloride (LY335979) in small volumes of human and murine plasma by ion-pairing reversed-phase high-performance liquid chromatography.

We have developed and validated a sensitive and selective method for the quantitative determination of the P-glycoprotein inhibitor zosuquidar (LY335979) in human and murine plasma using only 50 microl sample volumes. Sample pretreatment involved liquid-liquid extraction with tert-butyl methyl ether. Zosuquidar and the internal standard chlorpromazine were separated using a narrow bore column (2.1 mm x 150 mm) packed with 3.5 microm symmetry C(18) material. The mobile phase consisted of 38% (v/v) acetonitrile in 50mM ammonium acetate buffer pH 3.8 containing 0.005 M 1-octyl sulfonic acid and was delivered at 0.2 ml/min. Detection was performed with a fluorescence detector set at an excitation wavelength of 260 nm and an emission wavelength of 460 nm. The calibration curve was prepared in blank human plasma and was linear over the dynamic range (10-1000 ng/ml). The lower limit of quantitation was 20 ng/ml. The validation results showed that the assay was selective and reproducible. Within the range of the calibration curve the accuracy was close to 100% and within-day and between-day precision were within the generally accepted 15% range. This method was applied to study the pharmacokinetics of i.v. administered zosuquidar in mice. The sensitivity of the assay was sufficient to determine the drug concentration in plasma samples obtained up to 24 h after administration.

Concentrations of butriptyline in biological fluids following a fatal overdose.

A fatality resulting from the ingestion of butriptyline is reported. The compound was identified by mass spectral, gas chromatographic, and Fourier transform-infrared spectroscopic analysis. Identification was confirmed with a commercially available standard. Quantitation and identification details are presented.

P-glycoprotein-mediated active efflux of the anti-HIV1 nucleoside abacavir limits cellular accumulation and brain distribution.

P-glycoprotein (P-gp)-mediated efflux at the blood-brain barrier has been implicated in limiting the brain distribution of many anti-HIV1 drugs, primarily protease inhibitors, resulting in suboptimal concentrations in this important sanctuary site. The objective of this study was to characterize the interaction of abacavir with P-gp and determine whether P-gp is an important mechanism in limiting abacavir delivery to the central nervous system (CNS). In vitro and in vivo techniques were employed to characterize this interaction. Abacavir stimulated P-gp ATPase activity at high concentrations. The cellular accumulation of abacavir was significantly decreased by approximately 70% in Madin-Darby canine kidney II (MDCKII)-MDR1 monolayers compared with wild-type cells and was completely restored by the P-gp inhibitors ((R)-4-((1aR,6R,10bS)-1,2-difluoro-1,1a,6,10b-tetrahydrodibenzo(a,e)cyclopropa(c)cycloheptan-6-yl)-alpha-((5-quinoloyloxy)methyl)-1-piperazineethanol, trihydrochloride) (LY335979) and N-[4-[2-(6,7-dimethoxy-3,4-dihydro-1H-isoquinolin-2-yl)ethyl]phenyl]-5-methoxy-9-oxo-10H-acridine-4-carboxamide (GF120918). Directional flux experiments indicated that abacavir had greater permeability in the basolateral-to-apical direction (1.58E-05 cm/s) than in the apical-to-basolateral direction (3.44E-06 cm/s) in MDR1-transfected monolayers. The directionality in net flux was abolished by both LY335979 and GF120918. In vivo brain distribution studies showed that the AUC(plasma) in mdr1a(-/-) CF-1 mutant mice was approximately 2-fold greater than the AUC(plasma) in the wild type, whereas the AUC(brain) in the mutant was 20-fold higher than that in the wild type. Therefore, the CNS drug targeting index, defined as the ratio of AUC brain-to-plasma for mutant over wild type, was greater than 10. These data are the first in vitro and in vivo evidence that a nucleoside reverse transcriptase inhibitor is a P-gp substrate. The remarkable increase in abacavir brain distribution in P-gp-deficient mutant mice over wild-type mice suggests that P-gp may play a significant role in restricting the abacavir distribution to the CNS.

Dependence of nelfinavir brain uptake on dose and tissue concentrations of the selective P-glycoprotein inhibitor zosuquidar in rats.

Most reverse transcriptase and protease inhibitors used in highly active antiretroviral therapy for treating human immunodeficiency virus (HIV) infections exhibit poor penetration into the brain, raising the concern that the brain may be a sanctuary site for the development of resistant HIV variants. This study explores the relationship between the dose and plasma and brain concentrations of zosuquidar and the effect of this selective P-glycoprotein inhibitor on central nervous system penetration of the HIV protease inhibitor nelfinavir maintained at steady state by intravenous infusions in rats. Nelfinavir was infused (10 mg/kg/h) for up to 10 h with or without concurrent administration of an intravenous bolus dose of 2, 6, or 20 mg/kg zosuquidar given at 4 h. Brain tissue and plasma were analyzed for both drug concentrations. Brain tissue/plasma nelfinavir concentration ratios (uncorrected for the vascular contribution) increased nonlinearly with zosuquidar dose from 0.06 +/- 0.03 in the absence of zosuquidar and 0.09 +/- 0.02 between 2 and 6 h after 2 mg/kg zosuquidar to 0.85 +/- 0.19 after 6 mg/kg and 1.58 +/- 0.67 after 20 mg/kg zosuquidar. Zosuquidar brain tissue/plasma concentration ratios exhibited a similar abrupt increase from 2.8 +/- 0.3 after a 2 mg/kg dose to approximately 15 after the 6 and 20 mg/kg doses. The apparent threshold in the plasma concentration of zosuquidar necessary to produce significant enhancement in brain uptake of nelfinavir appears to be close to the plasma concentrations associated with the maximum tolerated dose reported in the literature after repeated dosing of zosuquidar in patients.

Role of drug efflux carriers in the healthy and diseased brain.

The blood-brain barrier is a natural diffusion barrier, which expresses active carriers extruding drugs on their way to the brain back into the blood against concentration gradients. Whereas these so-called adenosine triphosphate-binding cassette (ABC) transporters prevent the brain entry of toxic compounds under physiological conditions, they complicate pharmacotherapies in neurological disease. Recent observations in animal models of ischemic stroke, drug-resistant epilepsy, and brain cancer showed that the prototype of ABC transporters, ABCB1, is upregulated on brain injury, deactivation of this carrier considerably enhancing the accumulation of neuroprotective, antiepileptic, and chemotherapeutic compounds. These studies provide the proof of concept that the efficacy of brain-targeting drugs may significantly be improved when drug efflux is blocked. Under clinical conditions, efforts currently are made to enhance drug accumulation by selecting new compounds that do not bind to efflux carriers or deactivating ABC transporters by targeted downregulation or pharmacological inhibition. We predict that strategies aiming at circumventing drug efflux may greatly facilitate progress in neurological therapies.

Gas chromatographic-mass spectrometric assessment of the pharmacokinetics of amineptine and its main metabolite in volunteers with liver impairment.

A pharmacokinetic study of amineptine (Survector) and its C5 metabolite, resulting from a beta-oxidation of the heptanoic acid side-chain, was undertaken with ten human volunteers, who received a single 100-mg tablet of amineptine orally. They were affected with liver impairment in order to determine if this situation would alter greatly the pharmacokinetic parameters. The internal standard was the octanoic acid homologue. Analyses were carried out by gas chromatography (GC) and GC-mass spectrometry using TMS ester derivatives. Plasma samples were extracted using a C18 reversed-phase cartridge at pH 4.0. Mass fragmentographic measurements on the plasma samples were performed on the m/z ions (M + H)+ and (base peak)+ using ammonia chemical ionization. The global evaluation of precision was good and the coherence between the two modes of measurements, (base peak)+ and (M + H)+ ions, gave a regression factor r close to unity. For amineptine the total body clearance and mean residence time were accurate and precise with eight volunteers, but only four volunteers showed such coherent data for the slope of the elimination curve, beta, and half-life. However, the beta value, half-life and mean residence time of the C5 metabolite were accurate and precise with seven, eight and ten volunteers, respectively. It is concluded that the drug was still detoxified at normal levels.

Determination of amineptine and its main metabolite in plasma by high-performance liquid chromatography after solid-phase extraction.

Amineptine and its main metabolite were determined simultaneously in plasma by high-performance liquid chromatography using quinupramine as internal standard. The method comprised adsorption on Extrelut column from alkaline plasma, elution with diethyl ether-methylene chloride, evaporation in the presence of 0.01 M hydrochloric acid and injection of the acid solution onto a mu Bondapak C18 column, using acetonitrile-0.025 M potassium dihydrogenphosphate as mobile phase and ultraviolet detection at 210 nm. Average steady-state concentrations of the two compounds were determined in four patients under treatment regimen (two 100-mg doses of amineptine per day, at 8.00 and 12.00 h). The concentrations determined 20 h after the last dose were undetectable in all cases, whereas the concentrations determined 1 h after the second dose were found to be 780 +/- 96 ng ml-1 for amineptine and 690 +/- 137 ng ml-1 for its metabolite. The technique can also be applied to whole blood with, if necessary, identification on the basis of the ultraviolet spectrum obtained by photodiode-array detection.

Synthesis and receptor binding studies of (+/-)1-iodo-MK-801.

The glutamate analogue N-methyl-D-aspartate (NMDA) binds to a subset of glutamate receptors that are coupled to a voltage-sensitive cation channel. This NMDA-linked channel is the likely binding locus of the potent anticonvulsant MK-801. To develop single-photon emission computed tomography (SPECT) probes of this brain channel, we synthesized (+/)1-iodo-MK-801 and (+/-)1-[125I]iodo-MK-801. The effect of (+/-)1-iodo-MK-801 on ligand binding to the NMDA-linked glutamate receptor site was assessed using a rat brain homogenate assay. (+/-)1-Iodo-MK-801 displaced the dissociative anesthetic ligand [3H]N-[1-(2-thienyl)cyclohexyl]piperidine ([3H]TCP) binding with an IC50 of 1 microM, which is a 10-fold lower binding affinity than that of (+/-)MK-801. In in vivo autoradiographic studies, (+/-)MK-801 failed to block selective uptake of (+/-)1-iodo-MK-801 in rat brain. These results suggest that (+/-)1-iodo-MK-801 may not be a suitable ligand for mapping NMDA-linked glutamate receptor channels.