Results and evaluation of a first-in-human study of RG7342, an mGlu5 positive allosteric modulator, utilizing Bayesian adaptive methods.

AIM: The objectives of this first-in-human study were to evaluate the safety and tolerability, pharmacokinetics and pharmacodynamics, and maximum tolerated dose (MTD) of single ascending oral doses of RG7342, a positive allosteric modulator (PAM) of the metabotropic glutamate receptor 5 (mGlu5) for the treatment of schizophrenia, in healthy male subjects. METHODS: This was a single-centre, randomized, double-blind, adaptive study of 37 subjects receiving single ascending oral doses of RG7342 (ranging from 0.06-1.2 mg, n = 27) or placebo (n = 10). A modified continual reassessment method, with control for the probability of overdosing based on the occurrence of dose-limiting events (DLEs), was applied to inform the subsequent dose decisions for RG7342. RESULTS: DLEs consisted of dizziness, nausea and vomiting, and the incidence and severity of these adverse events increased in a concentration-dependent manner. RG7342 doses of 1.2 mg under fasting conditions, which reached a mean maximum plasma concentration (Cmax ) of 10.2 ng ml-1 , were not tolerated (four out of six subjects experienced DLEs). RG7342 showed dose-proportional pharmacokinetics, with rapid absorption and a biphasic decline, and a mean terminal half-life estimated to be >1000 h. CONCLUSIONS: Single oral doses of RG7342 were generally tolerated up to 0.6 mg under fasting and 0.9 mg under fed conditions in healthy subjects. Bayesian adaptive methods describing the probability of DLEs were applied effectively to support dose escalation. MTDs (fasting, fed) were associated with a Cmax of 6.5 ng ml-1 . The development of RG7342 was discontinued owing to the potential challenges associated with a long half-life in context of the observed adverse events.

Preclinical and Early Clinical Profile of a Highly Selective and Potent Oral Inhibitor of Aldosterone Synthase (CYP11B2).

Primary hyperaldosteronism is a common cause of resistant hypertension. Aldosterone is produced in the adrenal by aldosterone synthase (AS, encoded by the gene CYP11B2). AS shares 93% homology to 11ß-hydroxylase (encoded by the gene CYP11B1), responsible for cortisol production. This homology has hitherto impeded the development of a drug, which selectively suppresses aldosterone but not cortisol production, as a new treatment for primary hyperaldosteronism. We now report the development of RO6836191 as a potent (Ki 13 nmol/L) competitive inhibitor of AS, with in vitro selectivity >100-fold over 11ß-hydroxylase. In cynomolgus monkeys challenged with synthetic adrenocorticotropic hormone, single doses of RO6836191 inhibited aldosterone synthesis without affecting the adrenocorticotropic hormone-induced rise in cortisol. In repeat-dose toxicity studies in monkeys, RO6836191 reproduced the adrenal changes of the AS-/- mouse: expansion of the zona glomerulosa; increased expression of AS (or disrupted green fluorescent protein gene in the AS-/- mouse); hypertrophy, proliferation, and apoptosis of zona glomerulosa cells. These changes in the monkey were partially reversible and partially preventable by electrolyte supplementation and treatment with an angiotensin-converting enzyme inhibitor. In healthy subjects, single doses of RO6836191, across a 360-fold dose range, reduced plasma and urine aldosterone levels with maximum suppression at a dose of 10 mg, but unchanged cortisol, on adrenocorticotropic hormone challenge, up to 360 mg, and increase in the precursors 11-deoxycorticosterone and 11-deoxycortisol only at or >90 mg. In conclusion, RO6836191 demonstrates that it is possible to suppress aldosterone production completely in humans without affecting cortisol production. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT01995383.

Lead optimization of thiazolo[5,4-c]piperidines: 3-cyclobutoxy linker as a key spacer for H(3)R inverse agonists.

The simpler, the better: H(3) histamine receptor (H(3)R) are of interest as therapeutic targets in cognitive and somnolence disorders. Here, lead optimization of H(3)R inverse agonists bearing a thiazolo[5,4-c]piperidine group gave rise to a clinical candidate with a much simpler unprecedented benzamide scaffold, displaying decreased hERG activity while maintaining high brain receptor occupancies.

Pharmacokinetic and technical comparison of Sandostatin® LAR® and other formulations of long-acting octreotide.

BACKGROUND: Sandostatin® LAR® (Novartis Pharma AG) is a long-acting repeatable formulation of the somatostatin analogue octreotide, the safety and efficacy of which has been established through 15 years of clinical experience. Recently, other formulations of octreotide using polymer poly(lactic-co-glycolic acid) technology have been developed. This study compares the composition and pharmacokinetic (PK) profile of Sandostatin LAR with three other versions of the depot delivery system (formulations A, B and C, available in selected countries). FINDINGS: Sandostatin LAR exhibited a characteristic concentration-time profile with a limited initial release of octreotide ('burst'), an erosion phase from weeks 3-5, and a slowly declining concentration to day 52. The PK profiles of formulations A and B were characterized by a large initial burst during days 0-2, with up to 41% of the overall area under the plasma-concentration time curve achieved. Low and variable octreotide concentrations were observed during the microparticle erosion phase (days 2-62 [day 82 formulation C]) for formulations A, B and C. Sandostatin LAR microparticles are spherical in shape with an average diameter of approximately 50 µm, determined by scanning electron microscopy evaluation. Formulation A had smaller, irregular microparticles, and formulations B and C exhibited a large range of particle diameters (< 20 to > 100 µm). Inductively coupled plasma-optical emission spectroscopy detected a high tin content of 104 mg/kg in formulation B, the presence of which may suggest inadequate purification following polymer synthesis using tin(II)-octoate as catalyst. PK profiles for formulations A, B and C after a single intramuscular injection of 4 mg/kg in male New Zealand rabbits differed markedly from the PK profile of Sandostatin LAR. CONCLUSIONS: Clear differences were seen between Sandostatin LAR and formulations A, B and C, including variations in microparticle size, shape and impurity content. Considering the significant differences in the octreotide release profile between Sandostatin LAR and the other formulations, the safety and efficacy of the other formulations cannot be inferred from the Sandostatin LAR efficacy and safety profile; each of these other formulations should be assessed accordingly.

Benzyl prolinate derivatives as novel selective KCC2 blockers.

The discovery and optimization of a novel class of selective submicromolar KCC2 blockers is described. Details of synthesis and SAR are given together with ADME properties of selected compounds. A methylsulfone residue on the R(1) phenyl group improved the overall general profile of these prolinate derivatives.

Drug metabolism and pharmacokinetics.

In this article, aspects of absorption, distribution, metabolism, and excretion have been described bearing in mind the pathogenesis of allergic diseases and their possible therapeutic opportunities. The importance of the routes of administration of the different therapeutic groups has been emphasized. The classical aspects of drug metabolism and disposition related to oral administration have been reviewed, but special emphasis has been given to intranasal, cutaneous, transdermal, and ocular administration as well as to the absorption and the subsequent bioavailability of drugs. Drug-metabolizing enzymes and transporters present in extrahepatic tissues, such as nasal mucosa and the respiratory tract, have been particularly discussed. As marketed antiallergic drugs include both racemates and enantiomers, aspects of stereoselective absorption, distribution, metabolism, and excretion have been discussed. Finally, a new and promising methodology, microdosing, has been presented, although it has not yet been applied to drugs used in the treatment of allergic diseases.

Leptin treatment markedly increased plasma adiponectin but barely decreased plasma resistin of ob/ob mice.

Adiponectin (ApN) and leptin are two adipocytokines that control fuel homeostasis, body weight, and insulin sensitivity. Their interplay is still poorly studied. These hormones are either undetectable or decreased in obese, diabetic ob/ob mice. We examined the effects of leptin treatment on ApN gene expression, protein production, secretion, and circulating levels of ob/ob mice. We also briefly tackled the influence of this treatment on resistin, another adipocytokine involved in obesity-related insulin resistance. Leptin-treated (T) obese mice (continuous sc infusion for 6 days) were compared with untreated lean (L), untreated obese (O), and untreated pair-fed obese (PF) mice. Blood was collected throughout the study. At day 3 or day 6, fat pads were either directly analyzed (mRNA, ApN content) or cultured for up to 24 h (ApN secretion). The direct effect of leptin was also studied in 3T3-F442A adipocytes. Compared with L mice, ApN content of visceral or subcutaneous fat and ApN secretion by adipose explants were blunted in obese mice. Accordingly, plasma ApN levels of O mice were decreased by 50%. Leptin treatment of ob/ob mice increased ApN mRNAs, ApN content, and secretion from the visceral depot by 50-80%. Leptin also directly stimulated ApN mRNAs and secretion from 3T3-F442A adipocytes. After 6 days of treatment, plasma ApN of ob/ob mice increased 2.5-fold, a rise that did not occur in PF mice. Plasma resistin of T mice was barely decreased. Leptin treatment, but not mere calorie restriction, corrects plasma ApN in obese mice by restoring adipose tissue ApN concentrations and secretion, at least in part, via a direct stimulation of ApN gene expression. Such a treatment only minimally affects circulating resistin. ApN restoration could, in concert with leptin, contribute to the metabolic effects classically observed during leptin administration.

Pre- and post-translational negative effect of beta-adrenoceptor agonists on adiponectin secretion: in vitro and in vivo studies.

The adipose-derived hormone, adiponectin (ApN), has a role in fuel homoeostasis, insulin action and atherosclerosis. Regulation of ApN by catecholamines has scarcely been investigated. We examined the effects of beta-adrenergic agonists (and their second messenger, cAMP) on ApN gene expression, production and secretion in mouse in vitro and in vivo; their effects in human fat were also briefly studied in vitro. beta-Adrenergic agonists and cAMP inhibited ApN gene expression in human visceral adipose tissue. Likewise, cAMP down-regulated ApN mRNAs in cultured mouse explants from visceral and subcutaneous regions. The amount of ApN released into the medium decreased concomitantly. cAMP also caused qualitative changes in ApN secretion. Under basal conditions, ApN was secreted as a single 32 kDa species. In the presence of cAMP, an additional and probably immature (not modified post-translationally) 30 kDa species was also sorted. This altered secretion resulted from cAMP-induced quantitative and qualitative changes of ApN within the adipocyte. Under basal conditions, the 32 kDa form of ApN was mainly associated with high-density microsomes (HDMs), while the 30 kDa species was confined to a pool recovered with the cytosol fraction. cAMP depleted intracellular ApN at the expense of both HDM and cytosol fractions, and abnormally targeted ApN species to the different subcellular compartments as a result of impaired maturation. beta-Adrenergic agonists mimicked the inhibitory effects of cAMP on ApN mRNA and secretion, the beta(3)-agonist BRL37344 being the most potent. Administration of BRL37344 to mice reduced ApN mRNAs in both adipose regions, and ApN levels in plasma. In conclusion, beta-agonists inhibited ApN production and maturation, and thus exerted a dual (pre- and post-translational) negative effect on ApN secretion by cultured mouse adipose explants. ApN inhibition by beta-agonists was reproduced in mouse in vivo and in humans in vitro. ApN down-regulation may have an important role in fuel homoeostasis, insulin resistance and stress-induced atherosclerosis.