Hepatitis C virus dynamics and cellular gene expression in uPA-SCID chimeric mice with humanized livers during intravenous silibinin monotherapy.

Legalon SIL (SIL) is a chemically hydrophilized version of silibinin, an extract of milk thistle (Silybum marianum) seeds that has exhibited hepatoprotective and antiviral effectiveness against hepatitis C virus (HCV) in patients leading to viral clearance in combination with ribavirin. To elucidate the incompletely understood mode of action of SIL against HCV, mathematical modelling of HCV kinetics and human hepatocyte gene expression studies were performed in uPA-SCID-chimeric mice with humanized livers. Chronically HCV-infected mice (n = 15) were treated for 14 days with daily intravenous SIL at 469, 265 or 61.5 mg/kg. Serum HCV and human albumin (hAlb) were measured frequently, and liver HCV RNA was analysed at days 3 and 14. Microarray analysis of human hepatocyte gene expression was performed at days 0, 3 and 14 of treatment. While hAlb remained constant, a biphasic viral decline in serum was observed consisting of a rapid 1st phase followed by a second slower phase (or plateau with the two lower SIL dosings). SIL effectiveness in blocking viral production was similar among dosing groups (median ε = 77%). However, the rate of HCV-infected hepatocyte decline, δ, was dose-dependent. Intracellular HCV RNA levels correlated (r = 0.66, P = 0.01) with serum HCV RNA. Pathway analysis revealed increased anti-inflammatory and antiproliferative gene expression in human hepatocytes in SIL-treated mice. The results suggest that SIL could lead to a continuous second-phase viral decline, that is potentially viral clearance, in the absence of adaptive immune response along with increased anti-inflammatory and antiproliferative gene expression in human hepatocytes.

OARSI Clinical Trials Recommendations: Soluble biomarker assessments in clinical trials in osteoarthritis.

The objective of this work was to describe requirements for inclusion of soluble biomarkers in osteoarthritis (OA) clinical trials and progress toward OA-related biomarker qualification. The Guidelines for Biomarkers Working Group, representing experts in the field of OA biomarker research from both academia and industry, convened to discuss issues related to soluble biomarkers and to make recommendations for their use in OA clinical trials based on current knowledge and anticipated benefits. This document summarizes current guidance on use of biomarkers in OA clinical trials and their utility at five stages, including preclinical development and phase I to phase IV trials. As demonstrated by this summary, biomarkers can provide value at all stages of therapeutics development. When resources permit, we recommend collection of biospecimens in all OA clinical trials for a wide variety of reasons but in particular, to determine whether biomarkers are useful in identifying those individuals most likely to receive clinically important benefits from an intervention; and to determine whether biomarkers are useful for identifying individuals at earlier stages of OA in order to institute treatment at a time more amenable to disease modification.

Application of biomarkers in the development of drugs intended for the treatment of osteoarthritis.

OBJECTIVE: Osteoarthritis (OA) is a chronic and slowly progressive disease for which biomarkers may be able to provide a more rapid indication of therapeutic responses to therapy than is currently available; this could accelerate and facilitate OA drug discovery and development programs. The goal of this document is to provide a summary and guide to the application of in vitro (biochemical and other soluble) biomarkers in the development of drugs for OA and to outline and stimulate a research agenda that will further this goal. METHODS: The Biomarkers Working Group representing experts in the field of OA biomarker research from both academia and industry developed this consensus document between 2007 and 2009 at the behest of the Osteoarthritis Research Society International Federal Drug Administration initiative (OARSI FDA initiative). RESULTS: This document summarizes definitions and classification systems for biomarkers, the current outcome measures used in OA clinical trials, applications and potential utility of biomarkers for development of OA therapeutics, the current state of qualification of OA-related biomarkers, pathways for biomarker qualification, critical needs to advance the use of biomarkers for drug development, recommendations regarding practices and clinical trials, and a research agenda to advance the science of OA-related biomarkers. CONCLUSIONS: Although many OA-related biomarkers are currently available they exist in various states of qualification and validation. The biomarkers that are likely to have the earliest beneficial impact on clinical trials fall into two general categories, those that will allow targeting of subjects most likely to either respond and/or progress (prognostic value) within a reasonable and manageable time frame for a clinical study (for instance within 1-2 years for an OA trial), and those that provide early feedback for preclinical decision-making and for trial organizers that a drug is having the desired biochemical effect. As in vitro biomarkers are increasingly investigated in the context of specific drug treatments, advances in the field can be expected that will lead to rapid expansion of the list of available biomarkers with increasing understanding of the molecular processes that they represent.

Evaluation of Levothyroxine Bioavailability after Oral Administration of a Fixed Combination of Soy Isoflavones in Post-menopausal Female Volunteers.

BACKGROUND: Post-menopausal women under treatment with levothyroxine for their medical conditions may take concomitantly dietary supplements containing soy isoflavones in combination to treat their post-menopausal symptoms. The aim of this study was to investigate the effect of a fixed combination of soy isoflavones on the oral bioavailability of levothyroxine in post-menopausal female volunteers. METHODS: 12 healthy post-menopausal female, who were on stable oral levothyroxine as replacement/supplementation therapy for hypothyroidism, received a single recommended oral dose of a food supplement containing 60 mg of soy isoflavones (>19% genistin and daidzin) concomitantly with (test) and 6 h later (reference) the administration of levothyroxine in a randomized, open label, crossover fashion. Plasma concentrations of levothyroxine and soy isoflavones (daidzin, daidzein, genistin, genistein, S-equol) were determined by LC-MS/MS. Pharmacokinetic (PK) parameters were determined by non-compartmental analysis. No effect of soy isoflavones was assumed if the 90% confidence intervals (CIs) for the estimated ratio test/reference was included in the acceptance limits 0.80-1.25 for PK parameters Cmax and AUCt. RESULTS: The test/reference ratios Cmax and AUCt of levothyroxine were very close to unity (1.02 and 0.99, respectively) and the corresponding 90% CIs (0.99-1.04 and 0.88-1.12, respectively) fell entirely within the acceptance bioequivalence limits. CONCLUSION: The combination of soy isoflavones used in the present investigation does not affect the rate and extent of levothyroxine absorption when administered concomitantly in post-menopausal women.

Pharmacokinetics, pharmacodynamics, and tolerability of cabergoline, a prolactin-lowering drug, after administration of increasing oral doses (0.5, 1.0, and 1.5 milligrams) in healthy male volunteers.

Cabergoline (CAB) a long-acting dopaminergic ergoline derivative, was given orally, in single doses of 0.5, 1.0, and 1.5 mg, to 12 healthy men in order to evaluate its PRL-lowering effect as well as its plasma pharmacokinetics and urinary excretion. Drug administrations were separated by 5-week washout periods. Blood samples for PRL and CAB determination were taken at baseline and for 840 h thereafter (every 1 h up to 4 h, every 4 h up to 12 h, every 24 h up to 168 h, and weekly up to 5 weeks). Fractional urine collections for CAB excretion were taken immediately before drug administration, every 4 h up to 12 h, and every 12 h up to 168 h. During the study period, blood pressure and heart rate were monitored at the same time periods of plasma sampling for CAB, and electrocardiographic tracings and hematological evaluations were performed before and after each treatment period. All CAB doses (0.5, 1.0, and 1.5 mg) produced in all subjects a complete PRL suppression (PRL < 1.0 micrograms/L), that occurred earlier and persisted longer with the two higher doses. PRL secretion areas [area under the curve (AUC) 0-48 h and 48-840 h] were higher after 0.5-mg than after 1.0- and 1.5-mg doses. In particular, in the first portion of the area, the difference between 0.5 mg and both 1.0 and 1.5 mg was highly statistically significant (P < 0.01) without significant differences between the two highest doses. Mean CAB maximal plasma concentrations (Cmax) were 33.3 +/- 3.69, 40.3 +/- 2.49, and 67.0 +/- 9.79 ng/L after 0.5, 1.0, and 1.5 mg CAB, respectively; time to Cmax was 2 h (median) for all doses; CAB AUC(0-168 h) after 0.5 mg CAB was significantly lower (P < 0.01) than after 1.5 mg CAB. The percentages of the administered doses of CAB excreted in urine were 1.1 +/- 0.1%, 1.1 +/- 0.1%, and 1.2 +/- 0.1% for the 0.5-, 1.0-, and 1.5 mg doses, respectively (P = NS). CAB AUCs(0-168 h) and Cmax normalized to the 1.0-mg dose were compared by two-way analysis of variance; no significant differences were found for CAB AUCs(0-168h); Cmax after 0.5 mg was significantly higher (P < 0.01) than after 1.0 and 1.5 mg CAB. A progressive decrease of systolic and diastolic blood pressure was observed, and symptomatic hypotension after the 1.0-mg dose did not allow one subject to receive the 1.5-mg dose. Other mild to moderate adverse events occurred only after 1.0 and 1.5 mg CAB. These results indicate that, in the dose range of 0.5-1.5 mg, the pharmacokinetics of CAB are dose independent, and that the pharmacodynamic data and the frequencies of adverse events of CAB are dose related, with no significant differences in the PRL-lowering effect of the 1.0- and 1.5-mg doses.

The oxidation of dopamine and epinine by the two forms of monoamine oxidase from rat liver.

Information on the "in vitro" oxidation of epinine by monoamine oxidase (MAO) compared to dopamine is very poor. The aim of this work was to study the oxidative deamination of epinine and dopamine by rat liver MAO-A and MAO-B. The contributions of MAO-A and B to the metabolism of dopamine (55% and 45%, respectively) and epinine (70% and 30%, respectively) were similar. The results of this study show that epinine is a substrate for both forms of MAO in rat liver, although the contribution of MAO A to the deamination of this secondary amine appears to be slightly more important than that of MAO B.

Lack of pharmacokinetic interaction between the selective dopamine agonist cabergoline and the MAO-B inhibitor selegiline.

The addition of a dopamine agonist and of a monoamine oxidase type B inhibitor to I-dopa has been suggested in the therapy of Parkinson's disease. The plasma pharmacokinetics of both cabergoline and I-dopa have previously been shown to remain unaffected when the two drugs are given concomitantly. This study aimed at examining whether the plasma pharmacokinetic parameters of cabergoline and selegiline are modified when given in combination. Selegiline is hardly detectable in plasma. Therefore, the plasma levels of its metabolites amphetamine, methamphetamine and desmetylselegiline were used to assess the effect of cabergoline co-administration. Plasma levels of the selegiline metabolites were determined first after selegiline administration (10 mg/day) for 8 days, and then after administration of both drugs for 22 additional days (day 30). Cabergoline plasma levels were measured on day 30, and then after administration of cabergoline (1 mg/day) alone for further 22 days. No statistical difference was found between the Cmax.ss, tmax.ss, AUC0-24h.ss, C0h.ss, C24h.ss values of cabergoline and of the selegiline metabolites when the two drugs were given alone or in combination, indicating the absence of pharmacokinetic interaction between cabergoline and selegiline.

Increase of poly(L-lysine) uptake but not fluid phase endocytosis in neuraminidase pretreated Madin-Darby canine kidney (MDCK) cells.

The uptake of Poly(L-lysine) conjugates in cultured cells has been used as a model for non-specific adsorptive endocytosis of cationic macromolecules. To study the effect of glycocalyx desialylation on the uptake of cationic macromolecules in epithelial cells, Madin-Darby canine kidney (MDCK) cell monolayers were treated with neuraminidase and incubated with Poly(L-lysine) conjugates. Neuraminidase pretreatment of MDCK cells resulted in a 40% increase in the uptake of Poly(L-lysine) whereas trypsin pretreatment did not. Neuraminidase pretreatment did not increase the endocytosis of fluid phase markers in MDCK cells, nor the uptake of Poly(L-lysine) in L929 fibroblasts. These results suggest that the negative charges, rather than the glycoprotein matrices of glycocalyx, play an important role in the control of the uptake of cationic macromolecules in epithelial cells.

Clinical and pharmacokinetic evaluation of L-dopa and cabergoline cotreatment in Parkinson's disease.

Previous investigations on the mutual pharmacokinetic influence of L-dopa and dopamine agonists in Parkinson's disease (PD) have shown controversial results. Two studies of the possible clinical and pharmacokinetic interaction between L-dopa and cabergoline were performed in 10 patients with de novo PD and 12 patients with fluctuating PD. In the first study (de novo patients), cabergoline was administered at increasing dosages until the maximum dosage of 2 mg/day once a day for 8 weeks; subsequently L-dopa (250 mg/day) was added. Blood levels of cabergoline were assayed in two different days, before starting L-dopa, and 1 week thereafter. In the second 8-week study (fluctuating patients), cabergoline was added to the current L-dopa therapy (maximum dosage 4 mg/day once a day). Blood levels of L-dopa were measured in two different days, before cabergoline was added, and at the end of the study. In both studies motor performance was evaluated by means of the Unified Parkinson's Disease Rating Scale (motor examination) and the Clinical Global Impression Scale; on-off diaries of daily motor condition also were filled by fluctuating patients. In patients with de novo PD, cabergoline pharmacokinetic parameters were unmodified by the adjunct of L-dopa, except that the time to reach the peak concentration (Tmax) significantly increased after L-dopa. In patients with fluctuating PD, no modification of L-dopa pharmacokinetics was observed before and after cabergoline coadministration. Clinical evaluations confirmed that cabergoline is effective in the treatment of advanced PD as well as in the management of de novo patients.

Development and validation of a bioanalytical method for the determination of the cholecystokinin type-1 (CCK(1)) receptor antagonist dexloxiglumide in human plasma.

A sensitive bioanalytical method for the measurement of dexloxiglumide, a new selective and potent cholecystokinin type-1 (CCK(1)) receptor antagonist, in plasma, is reported. The method is based on reversed-phase liquid chromatography with ultraviolet absorption detection. Samples are extracted under acidic conditions into an organic solvent, and following evaporation, reconstitution and centrifugation stages, the supernatant is injected on to an ODS column with detection at 244 nm. The method has been validated over the concentration range 0.2-20 microgram/ml, 0.2 microgram/ml being the lower limit of quantification. The overall precision and accuracy (expressed as relative error) of the method was less than 6.1 and 2.3%, respectively. Dexloxigulmide was shown to be stable in plasma when stored at -20 degrees C for at least 200 days. The method is suitable for studying the pharmacokinetics of dexloxiglumide in man.

Pharmacodynamics and relative bioavailability of cabergoline tablets vs solution in healthy volunteers.

The effect of formulation on the urinary pharmacokinetics, pharmacodynamics, and relative bioavailability of cabergoline was investigated. Twelve healthy female volunteers, aged 23-35 years, were treated, according to an open, randomized, crossover design, with cabergoline (1-mg single oral dose) both as tablets and as a solution. The two administrations were separated by a 4-week wash-out period. Cabergoline and prolactin were measured in urine and plasma, respectively, by specific radioimmunoassays. Blood samples were collected before and up to 30 days after dosing. Urine was collected before and up to 8 days after dosing. Cabergoline elimination half-lives calculated from urinary data were 68 and 63 h after administration of the tablets and the solution, respectively. Urinary excretion of unchanged cabergoline accounted, on average, for 1.92% (range, 0.14-3.26) and 1.80% (range, 0.67-3.09) of the dose after administration of the tablets and the aqueous solution, respectively. Relative bioavailability of tablets vs solution was 99% (geometric mean with the 90% confidence intervals of 68-144%). Prolactin levels in 10 out of 12 subjects fell below the detection limit of the assay (1.5 micrograms/L) after both treatments. The mean maximum prolactin decrease (ca. 70%) was achieved by 2 or 3 h after dosing; the effect persisted up to 9 days, being completely exhausted 23-28 days after dosing. The analysis of variance performed on the pharmacodynamic effects of the two cabergoline formulations indicated that the percent decreases of plasma prolactin levels were not significantly different for tablets and solution. These results indicate that the pharmacodynamics and relative bioavailability of cabergoline are not influenced by formulation, as tablets or solution.

Pharmacokinetics of dexloxiglumide after administration of single and repeat oral escalating doses in healthy young males.

OBJECTIVE: To assess the pharmacokinetics, safety and tolerability of dexloxiglumide, a new CCK1 receptor antagonist currently under development for the treatment of the constipation-predominant irritable bowel syndrome. SUBJECTS AND METHODS: Twelve volunteers were enrolled in the present study and received orally 100, 200 and 400 mg of dexloxiglumide as tablets as a single dose followed by repeated t.i.d. doses for 7 days according to a randomized, double-blind, double-dummy complete crossover design. Plasma and urine were collected before drug administration and up to 72 h after dosing. Dexloxiglumide plasma and urinary concentration, determined using validated HPLC methods with UV detection, were used for the pharmacokinetic analysis by standard noncompartmental methods. In addition, dexloxiglumide safety and tolerability were evaluated throughout the study period by performing standard laboratory tests, by recording vital signs and ECGs and by monitoring the occurrence and severity of adverse events. RESULTS: After a single oral administration, dexloxiglumide was rapidly bioavailable with mean t(max) ranging from 0.9 - 1.6 h at all doses. The mean peak plasma concentrations (Cmax) were 1.7+/-0.6, 5.4+/-1.7, and 11.9+/-4.7 microg/ml, and the mean area under the plasma concentration-time curves (AUC) were 4.4+/-3.3, 8.6+/-3.6, and 18.3+/-5.9 microg x h/ml at the 3 doses, respectively. Apparent plasma clearance (CL/F) was 30.8+/-13.9, 27.2+/-10.6, and 21.1+/-8.6 l/h at the 3 doses, respectively. The apparent elimination half-life from plasma (t1/2) ranged from 2.6 - 3.3 h at the 3 doses. The excretion of unchanged dexloxiglumide in 0 - 72 h urine accounted for approximately 1% of the administered dose and this was true for all doses. Dexloxiglumide renal clearance (CLR) averaged 0.4+/-0.4, 0.4+/-0.2, and 0.3+/-0.3 l/h for the 3 doses, respectively. After the last dose of the repeated dosing period dexloxiglumide Cmax occurred at 1.1 - 1.6 h after drug administration and averaged 2.4+/-1.3, 7.1+/-2.9, and 15.3+/-2.7 microg/ml for the 3 doses, respectively. The AUC values averaged 5.9+/-3.0, 16.0+/-8.8, and 50.8+/-38.1 microg x h/ml, respectively. The area under the plasma concentration-time curve calculated at steady state within a dosing interval (AUCss) averaged 4.6+/-1.6, 11.3+/-3.6, and 28.4+/-8.2 microg x h/ml, whereas CL/F averaged 20.3+/-8.3, 16.3+/-9.0, and 10.3+/-5.0 l/h at the 3 doses, respectively. Dexloxiglumide t1/2 could not be accurately calculated due to the high inter-subject variability and to sustained dexloxiglumide plasma concentrations that precluded the identification ofthe terminal phase of the plasma concentration-time profiles. However, it appeared that dexloxiglumide t1/2 was considerably prolonged at the dose of 400 mg. CLR averaged 0.4+/-0.4, 0.3+/-0.3, and 0.3+/-0.1 l/h for the 3 doses, respectively. After a single dose, the plasma pharmacokinetics of dexloxiglumide were dose-independent in the dose range 100 - 400 mg. After repeated dose the pharmacokinetics of dexloxiglumide were virtually dose-independent in the dose range 100 - 200 mg. A slight deviation from linear pharmacokinetics was found with a dose of 400 mg. Dexloxiglumide plasma pharmacokinetics were also time-independent in the dose range 100 - 200 mg with a deviation from expectation based on the superimposition principle with a dose of 400 mg. Dexloxiglumide urinary excretion and renal clearance were both dose- and time-independent in the dose range 100 - 400 mg. The safety and tolerability of dexloxiglumide administered to healthy young males was good up to the maximum investigated dose of 400 mg both after single and after repeated doses. CONCLUSIONS: The safety and pharmacokinetic profile of dexloxiglumide when the drug is administered as single and repeated doses in the dose range 100 - 400 mg provides the rationale for the choice of the treatment schedule (200 mg t.i.d.) for the efficacy trials in patients with (constipation-predominant) irritable bowel syndrome.

Absorption, distribution, metabolism and excretion of the cholecystokinin-1 antagonist dexloxiglumide in the dog.

Single oral doses of 14C-dexloxiglumide were rapidly and extensively absorbed in dogs and also eliminated rapidly with a short half-life. Following single intravenous doses, dexloxiglumide was characterised as a drug having a high clearance (30.7 and 27.0 ml/min/kg in males and females respectively), a low volume of distribution (Vss, 0.34 and 0.27 L/kg in males and females respectively) and a moderate systemic availability (about 33%). It was extensively bound to plasma proteins (89%). Dexloxiglumide is mainly cleared by the liver. Its renal clearance was minor. In only the kidney, liver and gastrointestinal tract, were concentrations of 14C generally greater than those in plasma. 14C concentrations generally peaked at 0.25h and declined rapidly during 24h being present only in a few tissues (such as the kidney, liver and gastrointestinal tract) at 24h. Single intravenous or oral doses were mainly excreted in the faeces (77-89%), mostly during 24h. Urine contained up to 7.5% dose. Mean recoveries during 7 days ranged between 93-97%. Biliary excretion of 14C was prominent (64% dose during 24h) in the disposition of 14C which was probably also subjected to some limited enterohepatic circulation. Unchanged dexloxiglumide was the major component in plasma. Urine and faeces contained several 14C-components amongst which unchanged dexloxiglumide was the most important (eg. about 55% dose in faeces). LC-MS/MS of urine and bile extracts showed that dexloxiglumide was metabolised mainly by O-demethylation and by conjugation with glucuronic acid.

Absorption, distribution, metabolism and excretion of the cholecystokinin-1 antagonist dexloxiglumide in the rat.

Single oral doses of 14C-dexloxiglumide were rapidly and extensively absorbed in rats, and eliminated more slowly by females than by males. The respective half-lives were about 4.9 and 2.1 h. Following single intravenous doses, dexloxiglumide was characterised as a drug having a low clearance (6.01 and about 1.96 ml/min/kg in males and females respectively), a moderate volume of distribution (Vss, 0.98 and about 1.1 L/kg in males and females respectively) and a high systemic availability. It was extensively bound to plasma proteins (97%). Dexloxiglumide is mainly cleared by the liver. Its renal clearance was minor. In only the liver and gastrointestinal tract, were concentrations of 14C generally greater than those in plasma. Peak 14C concentrations generally occurred at 1-2 h in males and at 2-4 h in females. Tissue 14C concentrations then declined by severalfold during 24 h although still present in most tissues at 24 h but only in a few tissues (such as the liver and gastrointestinal tract) at 168 h. Decline of 14C was less rapid in the tissues of females than in those of males. Single intravenous or oral doses were mainly excreted in the faeces (87-92%), mostly during 24 h and more slowly from females than from males. Urines contained less than 11% dose. Mean recoveries during 7 days when 14C was not detectable in the carcass except in one female rat ranged between 93-101%. Biliary excretion of 14C was prominent (84-91% dose during 24 h) in the disposition of 14C which was also subjected to facile enterohepatic circulation (74% dose). Metabolite profiles in plasma and selected tissues differed. In the former, unchanged dexloxiglumide was the major component whereas in the latter, a polar component was dominant. Urine, bile and faeces contained several 14C-components amongst which unchanged dexloxiglumide was the most important (eg. up to 63% dose in bile). LC-MS/MS showed that dexloxiglumide was metabolised mainly by hydroxylation in the N-(3-methoxypropyl)pentyl sidechain and by O-demethylation followed by subsequent oxidation of the resulting alcohol to a carboxylic acid.

Development and validation of a HPLC-ES-MS/MS method for the determination of glucosamine in human synovial fluid.

A new HPLC method for the determination of glucosamine (2-amino-2-deoxy-D-glucose) in human synovial fluid was developed and validated. Synovial fluid samples were analyzed after a simple protein precipitation step with trichloroacetic acid using a polymer-based amino column with a mobile phase composed of 10 mM ammonium acetate (pH 7.5)-acetonitrile (20:80, v/v) at 0.3 mL/min flow rate. D-[1-13C]glucosamine was used as internal standard. Selective detection was performed by tandem mass spectrometry with electrospray source, operating in positive ionization mode and in multiple reaction monitoring acquisition (m/z 180-->72 and 181-->73 for glucosamine and internal standard, respectively). The limit of quantification (injected volume=3 microL) was 0.02 ng, corresponding to 10 ng/mL in synovial fluid. Calibration curves obtained using matrix-matched calibration standards and internal standard at 600 ng/mL were linear up to 2000 ng/mL. Precision values (%R.S.D.) were < or = 14% in the entire analytical range. Accuracy (%bias) ranged from -11% to 10%. The recoveries measured at three concentration levels (50, 800, and 1500 ng/mL) were higher than 89%. The method was successfully applied to measure endogenous glucosamine levels in synovial fluid samples collected from patients with knee osteoarthritis and glucosamine levels after oral administration of glucosamine sulfate (DONA) at the dose of 1500 mg/day for 14 consecutive days (steady-state).

Synovial and plasma glucosamine concentrations in osteoarthritic patients following oral crystalline glucosamine sulphate at therapeutic dose.

OBJECTIVE: We investigated the synovial and plasma glucosamine concentrations in osteoarthritic patients following oral administration of crystalline glucosamine sulphate at the therapeutic dose of 1500mg once-a-day for 14 days. DESIGN: Twelve osteoarthritic patients (six males and six females) received 14 consecutive once-daily oral administrations of crystalline glucosamine sulphate soluble powder (1500mg), in an open fashion. Plasma and synovial fluid were collected simultaneously from the same patient, at baseline and, at steady state (3h after the last dose). Glucosamine was determined in plasma and synovial fluid by liquid chromatography-tandem mass spectrometry. RESULTS: Median endogenous glucosamine concentrations in plasma and synovial fluid were 52.0ng/ml (0.29microM) and 36.5ng/ml (0.21microM), respectively (P=0.001), and varied substantially among patients (41-121ng/ml and <10-67ng/ml, respectively). Three hours after the last dose, glucosamine concentrations resulted increased from baseline in all patients with median increases of 20.5 and 21.5 folds in plasma and synovial fluid, respectively, the difference being not statistically significant (P=0.11). In plasma, the median post-treatment value was 1282ng/ml (7.17microM) and ranged from 600 to 4061ng/ml (3.35-22.7microM). The median post-treatment synovial glucosamine concentration was 777ng/ml (4.34microM), i.e., significantly lower than in plasma (P=0.001), and ranged from 577 to 3248ng/ml (3.22-18.1microM). Plasma and synovial glucosamine concentrations were highly correlated and were in the 10microM range. CONCLUSIONS: Glucosamine is bioavailable both systemically and at the site of action (the joint) after oral administration of crystalline glucosamine sulphate in ostaeoarthritis patients. Steady state glucosamine concentrations in plasma and synovial fluid were correlated and in line with those effective in selected in vitro studies.

Glucosamine oral bioavailability and plasma pharmacokinetics after increasing doses of crystalline glucosamine sulfate in man.

OBJECTIVE: Pharmacokinetic data on glucosamine are scant, limiting the understanding of glucosamine sulfate mechanism of action in support of its treatment effects in osteoarthritis. This study investigated the oral pharmacokinetics and dose-proportionality of glucosamine after administration of the patented crystalline glucosamine sulfate in man. METHODS: Twelve healthy volunteers received three consecutive once-daily oral administrations of glucosamine sulfate soluble powder at the doses of 750, 1,500, and 3,000 mg, in an open, randomised, cross-over fashion. Glucosamine was determined in plasma collected up to 48 h after the last dose by a validated Liquid Chromatography method with Mass Spectrometry detection. Pharmacokinetic parameters were calculated at steady state. RESULTS: Endogenous plasma levels of glucosamine were detected (10.4-204 ng/ml, with low intra-subject variability). Glucosamine was rapidly absorbed after oral administration and its pharmacokinetics were linear in the dose range 750-1,500 mg, but not at 3,000 mg, where the plasma concentration-time profiles were less than expected based on dose-proportionality. Plasma levels increased over 30-folds from baseline and peaked at about 10 microM with the standard 1,500 mg once-daily dosage. Glucosamine distributed to extravascular compartments and its plasma concentrations were still above baseline up to the last collection time. Glucosamine elimination half-life was only tentatively estimated to average 15 h. CONCLUSIONS: Glucosamine is bioavailable after oral administration of crystalline glucosamine sulfate, persists in circulation, and its pharmacokinetics support once-daily dosage. Steady state peak concentrations at the therapeutic dose of 1,500 mg were in line with those found to be effective in selected in vitro mechanistic studies. This is the only glucosamine formulation for which pharmacokinetic, efficacy and safety data are now available.

Transcellular processing of disulfide- and thioether-linked peroxidase--polylysine conjugates in cultured MDCK epithelial cells.

Horseradish peroxidase (HRP) was conjugated to nondegradable polycationic poly(D-lysine) (PDL) through either a thioether (HRP-S-PDL) or a disulfide (HRP-SS-PDL) linkage. The binding and transcytosis of these conjugates was studied in Madin-Darby canine kidney (MDCK) cell monolayers grown on 3-microns microporous polycarbonate filters. Conjugation of HRP to PDL with both linkages markedly increased the binding of this protein onto the cell monolayers. However, an enhancement of the transcellular transport of HRP in both apical-to-basal and basal-to-apical directions was observed only in HRP-SS-PDL, but not in HRP-S-PDL. HRP-SS-PDL transport was inhibited by colchicine and by 4 degrees C incubation. The transport of 14C-sucrose was not affected by the presence of conjugates. These results indicate that the transport of the conjugate across the cell monolayers was due to a transcellular process rather than to any leakage of the cell junction caused by polycations. The disulfide linkage between HRP and PDL was cleaved rapidly at the basal and, to a lesser extent, at the apical surface of the cell. Neuraminidase treatment decreased the binding of the conjugates onto the cell surface, but did not decrease the transcellular transport, suggesting that not all surface-bound conjugates were available for transcytosis. These results demonstrate that disulfide linkages can be cleaved during transcytosis in MDCK cells. The cleavage, however, occurs mostly at the binding site on the cell surface, which may prevent the cellular uptake of the intact conjugate.

A double-blind, placebo-controlled study to assess tolerability, pharmacokinetics and preliminary pharmacodynamics of single escalating doses of Z13752A, a novel dual inhibitor of the metalloproteases ACE and NEP, in healthy volunteers.

AIMS: The objective of this study was to evaluate the tolerability of a novel dual ACE-NEP inhibitor, Z13752A, after the oral administration of rising single doses in healthy volunteers. This study was also a preliminarily investigation of Z13752A pharmacodynamics (PD) and pharmacokinetics (PK). METHODS: In this randomized, placebo-controlled, sequential study, two alternating panels of eight healthy male volunteers each (six subjects receiving the active treatment + two subjects receiving placebo) were treated with increasing oral doses of Z13752A: 10, 50, 200, and 600 mg were given to panel I and 20, 100, 400 and 800 mg were given to panel II. The study was double-blind relative to placebo or active treatment, and was open with respect to the dose levels. The same volunteer received placebo only once. RESULTS: Single oral doses of Z13752A, as high as 800 mg, were well tolerated. Only six mild-to-moderate adverse events mainly headache, were reported and appeared to be of little clinical relevance. After administration of 200, 400, 600 and 800 mg of Z13752A, a nonsignificant fall in diastolic blood pressure was detected, in both the standing and supine position. After single oral doses of Z13752A, ACE inhibition appeared to be significant at all the doses tested, linearly correlated with the dose and was almost complete at doses > or = 100-200 mg. NEP inhibition was indicated by elevation of ANP and cGMP plasma concentrations in almost all subjects. In the 200-800 mg dose range, Z13752A produced a 50-100% increase of plasma cGMP levels and a 50-80% elevation in urinary cGMP concentrations. Detectable plasma levels of Z13752A were found in all the treated subjects. Z13752A was well and rapidly absorbed, with peak concentrations reached approximately 2.5 h after administration. The mean apparent elimination half-life from plasma was approximately 12 h. The pharmacokinetics of Z13752A after single oral doses were characterized by low intersubject variability and appeared to be dose-independent. CONCLUSIONS: Z13752A showed a good single dose tolerability profile at doses up to 800 mg. The pharmacokinetic data indicate that Z13752A administered orally is rapidly absorbed and available to the systemic circulation in humans. The relatively slow clearance indicates that a once-a-day dose regimen could be considered for Z13752A.

The effect of food on cabergoline pharmacokinetics and tolerability in healthy volunteers.

The effect of food on the pharmacokinetics and tolerability of cabergoline in man was investigated. For this purpose an open, randomized, single-dose study was conducted in 12 healthy male volunteers who received 1 mg cabergoline as tablets both under fasting conditions and after a breakfast containing a substantial amount of carbohydrates, fat, and proteins, in a crossover fashion. The two treatments were separated by a 4 week washout period. Plasma and urine were collected up to 336 and 168 h respectively after administration and cabergoline concentration was measured in both fluids using a validated radioimmunoassay. Tolerability assessment included haematology, blood chemistry, and urinalysis, blood pressure and heart rate measurements, and ECG. Under both fasting and fed conditions low but persistent cabergoline plasma levels were observed in the present study up to 2 weeks after drug intake, in agreement with the long-lasting prolactin-lowering activity of the drug. In subjects receiving cabergoline under fed or fasting conditions, Cmax values averaged 44 and 54 pg mL(-1), AUC(0-336 h) averaged 6392 and 5331 pg h mL(-1), Ae(0-168 h) averaged 12.7 and 11.9 micrograms, and t1/2 averaged 109.7 and 101.3 h, respectively. No statistically significant difference was found when Cmax, AUC(0-336 h), t1/2, and Ae(0-168 h) from subjects treated under fasting and fed conditions were compared. Median tmax values in subjects treated under fasting or fed conditions were identical (2.5 h). The statistical analysis applied to the parameters chosen to evaluate the variations in the blood pressure profiles observed either supine or standing did not show any significant difference between the fed and fasting conditions. Heart rate values were not significantly modified after cabergoline under either fed or fasting conditions. Laboratory evaluation showed some minor deviations from normal, which were not clinically relevant (only one subject showed an occasional and transient elevation in alkaline phosphatase which disappeared in the subsequent laboratory evaluations) and were considered for the most part not to be drug related. Eleven subjects reported adverse events (one after both treatments, five only after drug intake under fasting conditions, and five only after drug intake with food.