Pharmacokinetics of the amidine prodrug of a novel oral anticoagulant factor VIIa inhibitor (AS1924269-00) in rats.

AS1924269-00 is a promising orally applicable anticoagulant that inhibits FVIIa but has very low oral absorption. Therefore, in this study, we aimed to develop a prodrug of AS1924269-00, which possesses a carbamate-added amidine functional group, with high membrane permeability. We investigated the pharmacokinetics of the carbamate-type prodrug of AS1924269-00 in rats. The Caco-2 cell monolayer was used as an in vitro model and in parallel an artificial membrane permeability assay (PAMPA) was performed to examine the transport mechanisms of the prodrug. The bioavailability of the active form was determined to be only 0.3% in rats, but the oral absorption of the prodrug was markedly improved, and its bioavailability was 36%. Our in vivo result was consistent with the finding that compared to AS1924269-00, the prodrug showed favorable permeability in Caco-2 cells and PAMPA. We introduced carbamate into the amidine functional group of the FVIIa inhibitor, which possesses the amidine backbone, and converted it to a prodrug using carboxylic acid ethyl ester. This novel prodrug had favorable absorption and membrane permeability in vivo and in vitro. Thus, we suggest a clinical application of the carbamate-added amidine prodrug of the FVIIa inhibitor.

Pharmacological activation of peroxisome proliferator-activated receptor δ improves insulin resistance and hepatic steatosis in high fat diet-induced diabetic mice.

The mechanisms regarding hepatic steatosis related to hepatic insulin resistance have been well documented. However, the agents for treatment of hepatic steatosis and insulin resistance remain poorly developed. Peroxisome proliferator-activated receptors (PPARs) are transcription factors that are responsible for the regulation of glucose and/or lipid metabolism. There are 3 distinct isoforms of PPARs family: PPARα, PPARγ, and PPARδ. Both PPARα and PPARγ agonists are widely used in clinic for the treatment of hyperlipidemia and hyperglycemia. However, the therapeutic efficacy of PPARδ agonists for diabetic disorders remains obscure. In the present study, we used L-165041 as PPARδ agonist to treat the high fat diet (HFD) fed mice. Administration of L-165041 improved the hepatic steatosis and increased the insulin sensitivity in HFD-mice. In addition to the histological identification of hepatic steatosis, the improvement of insulin sensitivity was characterized by the enhanced insulin signals and the increase of hepatic glycogen content. This is the first report showing that pharmacological activation of PPARδ improves insulin resistance in diet-induced diabetic mice. Thus, we suggest that pharmacological activation of PPARδ may be a new strategy for the treatment of diabetic patients with hepatic steatosis.

Pharmacological discrimination of extinction and reconsolidation of contextual fear memory by a potentiator of AMPA receptors.

Conditioned fear memory, once formed through fear conditioning, is modulated by reexposure of individuals to a conditioned stimulus. The reexposure reactivates the fear memory, which induces reconsolidation of the memory first, and then extinction of the fear response. Both attenuating the former and facilitating the latter are effective in reducing the fear response, and these findings are potentially translatable to the enhancement of exposure therapy for complex anxiety disorders. Currently, there is no drug that is established to modulate either reconsolidation or extinction selectively, which are thought to be independent processes. Here, we report that an extinction-facilitating AMPA potentiator, 4-[2-(phenylsulfonylamino)ethylthio]-2,6-difluoro-phenoxyacetamide (PEPA), does not act on the reconsolidation of fear memory formed by contextual fear conditioning in mice. The freezing rates observed in contextually conditioned mice following short reexposure (3 min) to the context were not influenced by intraperitoneal or intra-amygdala administration of PEPA. The same short reexposure to the context enhanced freezing responses in mice that were similarly administered D-cycloserine (DCS), a drug that facilitates both extinction and reconsolidation, and this enhancement of freezing responses in mice intraperitoneally administered DCS was abolished by propranolol, a drug that suppresses reconsolidation. At the same doses used in the short reexposure experiments, PEPA and DCS facilitated extinction of the fear response induced by long reexposure to the context and suppressed reinstatement of the conditioned fear memory. PEPA and DCS did not affect reextinction. These results suggest that PEPA acts on extinction of contextual fear memory without having detectable influences on its reconsolidation.

[Using solutions of hydroxyethyl starch (6% HES 200/0.5 (refortan) and 6% HES 130/0.4 (voluven)) in neuroanesthesiology].

The paper provides the results of a complex experimental and clinical study of the effects of infusion solutions of hydroxyethyl starch (HES 200/0.5--Refortan and HES 130/0.4--Voluven) on hemostatic and systemic hemodynamic parameters in patients operated on for neurosurgical pathology of the brain. The HES solutions are shown to have a more pronounced volemic effect and a slightly higher hypocoagulation effect on the hemostatic system (as compared with physiological solution); the latter does not, however, achieve its clinical value with the used doses of the solutions.

Effect of PPAR-delta agonist on the expression of visfatin, adiponectin, and resistin in rat adipose tissue and 3T3-L1 adipocytes.

It has been recently reported that activation of PPAR-delta, by specific agonists or genetic manipulation, alleviates dyslipidemia, hyperglycemia, and insulin resistance in animal models of obesity and type 2 diabetes. The purpose of the present study was to determine whether the PPAR-delta agonist has a direct effect on adipokines in visceral adipose tissue of rats and in cultured adipocytes. We examined the expression of visfatin, adiponectin, and resistin mRNA in visceral adipose tissue of Wistar rats fed a high-fat diet and 3T3-L1 adipocytes treated with PPAR-delta agonist (L-165041). Body weight and biochemical measurements were performed. Rats fed a high-fat diet showed a greater increase in body weight than those fed a standard diet (P<0.05), and treatment with L-165041 (10 mg/kg/day) significantly decreased weight gain (P<0.05). The concentration of total cholesterol was lower, and HDL cholesterol was higher in L-165041-treated rats (P<0.05). In the visceral adipose tissue of L-165041-treated rats, visfatin and adiponectin mRNA levels significantly increased compared to those of the untreated rats (P<0.05). However, the expression of resistin decreased in the L-165041-treated rats. Furthermore, in cultured 3T3-L1 adipocytes, the level of visfatin and adiponectin mRNA was up-regulated in response to L-165041 treatment for nine days. By contrast, resistin mRNA levels were down-regulated by L-165041 treatment. The present study provides a novel evidence to suggest that the PPAR-delta agonist has regulatory effects on a variety of adipokines, and these effects might explain some of their metabolic function.

[Experience with using of solutions of hydroxyethyl starch (refortan and voluven) in neuroanesthesiology].

The investigation has shown that solutions of hydroxyethyl starch included in complex infusion therapy facilitate stabilization of hemodynamics in neurosurgical patients during surgery. Refortan exerts a more pronounced effect on the indices of hemodynamics as compared with voluven, but its modifying action on the hemostasis system is also more pronounced. These medicines used in doses 6-8 ml/kg fail to have substantial effects on efficiency of hemostasis in the brain wound and do not increase risk of postoperative hemorrhagic complications.

Paradoxical effects of aurintricarboxylic acid and RG-13577: acute thrombosis and in-stent stenosis in a passive-coated stent.

PURPOSE: To investigate if a platelet inhibitor (aurintricarboxylic acid [ATA]) and a heparin-mimicking antagonist (RG-13577) of basic fibroblast growth factor 2 (bFGF2) could be combined as a stable compound and attached to conventional bare metal stents to hinder thrombus formation and inflammatory reactions of stenting. METHODS: Fifteen domestic pigs were stented with RG-13577/ATA-coated (n=6), ATA-coated (n=12), and bare metal stents (n=12) in the left anterior descending (LAD) and left circumflex (LCX) coronary arteries. All surviving pigs were evaluated with contrast angiography and intravascular ultrasonography (IVUS) after 4 weeks. Histological analysis of the stented arteries was performed after hematoxylin-eosin staining. Tissue factor (TF) staining and scanning electron microscopy (SEM) were performed in animals with acute stent thrombosis. RESULTS: Five of the 6 animals receiving an RG-13577/ATA-coated stent experienced acute stent thrombosis, while no adverse events occurred in the animals of the other 2 groups. Follow-up angiography did not show significant in-stent stenosis in either bare or ATA-coated stents. However, histomorphometry revealed larger neointimal area (3.54+/-0.69 mm2 versus 1.82+/-0.27 mm2, p<0.05) and outward plaque area (1.56+/-0.34 mm2 versus 0.61+/-0.12 mm2, p<0.05) in ATA-coated stents. Three-dimensional IVUS analysis showed analogous results, with significantly larger neointimal volume and outward plaque volume in ATA-coated stents. There was a slight increase in TF staining around the stent struts, while SEM showed increased platelet adhesion and activity in RG-13577/ATA-coated stents versus the ATA-coated and bare metal stents. CONCLUSION: RG-13577/ATA-coated stents lead to acute stent thrombosis. The ATA coating alone did not lead to acute events, but resulted in higher neointimal hyperplasia and expansive remodeling. These results underline the importance of preclinical studies before using new coated stents in human arteries.

[Comparative evaluation of different infusion medias used in therapy for neonatal hypovolemia].

The paper comparatively evaluates the efficiency of the use of physiological sodium chloride solution, freshly-frozen plasma, 6% and 10% solutions of hydroxyethyl starch to compensate for circulating blood volume deficit in 80 neonatal infants aged 1-3 days who had hypovolemia resulting from hemorrhage during labor or abdominal delivery. 6% and 10% solutions of hydroxyethyl starch were found to be the most effective agents for compensating for circulating plasma volume deficit. They rapidly eliminate circulating blood volume deficit, long maintain the stability of systemic and peripheral hemodynamic parameters.

Stimulation of nonshivering thermogenesis in the Syrian hamster by norepinephrine and beta-selective adrenergic agents: a phenomenon of refractoriness.

The ability of different adrenergic agents to stimulate nonshivering thermogenesis in Syrian hamsters was investigated. The hamsters were cold-acclimated to 6 degrees C and their thermogenic response was investigated in an open-circuit system at 24 degrees C. Both norepinephrine and the beta 3-specific adrenergic agonist CGP-12177 induced a high rate of nonshivering thermogenesis. However, neither CGP-12177 nor other beta 3-selective agonists (BRL-37344, ICI-D7114) could induce nonshivering thermogenesis fully to the extent induced by norepinephrine. It was further observed that an apparent "thermogenic refractoriness" was induced by certain adrenergic agents (isoprenaline, CGP-12177) but not by others (norepinephrine, BRL-37344, ICI-D7114). It is discussed whether the refractoriness could be secondary to effects of these agents on the vascular system. It is pointed out that the thermogenic response to adrenergic stimulation observed in the intact animal does not always fully correspond to what would be predicted from corresponding studies with isolated brown-fat cells.

Dissolution studies of microencapsulated 4-sulphonamidophenoxyacetic acid: effect of preparative variables on dissolution.

Ethylcellulose-walled microcapsules of 4-sulphonamidophenoxyacetic acid were prepared and their in vitro dissolution characteristics were investigated. Different release kinetics must be applied according to the respective average particle size and wall content values of the microcapsule fractions. The 'dissolution model' appears to fit better with small thin-walled microcapsules whereas, for larger thicker-walled microcapsules, Higuchi-type kinetics seem to describe the release of the major part of the drug more adequately.

Comparative effects of ticrynafen and hydrochlorothiazide in the treatment of hypertension.

Two dose levels of ticrynafen, a new uricosuric diuretic, and of hydrochlorothiazide were randomly assigned, double-blind to 240 men with initial diastolic blood pressures in the range of 95 to 114 mm Hg. A dose of 500 mg of ticrynafen once daily exerted an antihypertensive effect comparable to that of 50 or 100 mg of hydrochlorothiazide. Whereas serum uric acid levels rose in patients treated with hydrochlorothiazide, they fell markedly in those receiving ticrynafen. Otherwise, both diuretics produced similar chemical changes in serum. Patients tolerated ticrynafen as well as they did hydrochlorothiazide over a period of six months of observation, and there was no evidence of serious toxicity or loss of therapeutic effect with ticrynafen. This antihypertensive agent, in appropriate doses, appears to be as effective and well tolerated as hydrochlorothiazide, and in addition ticrynafen prevents hyperuricemia.

Biochemical and haematological changes induced by tienilic acid combined with propranolol in essential hypertension.

Sixteen patients with moderate essential hypertension completed a double-blind crossover trial with four treatment periods each of 6 weeks. They received in random order: placebo; tienilic acid 250 mg/day; propranolol 80 mg twice daily; and tienilic acid 250 mg/day combined with propranolol 80 mg twice daily. Average blood-pressure in the lying position was 22.6/13.1 kPa (169/98 mm Hg) on placebo; 21.0/12.5 (157/94) on tienilic aicd; 21.2/12.0 (159/90) on propranolol, and 18.9/11.5 (142/86) on tienilic acid combined with propranolol. The effects of tienilic acid and propranolol on blood-pressure were additive and there were no statistically significant interactions. Tienilic acid significantly reduced serum-urate from 0.33 to 0.18 mmol/l and induced hypokalaemia which was corrected by propranolol. Basophil count and haemoglobin were lower after tienilic acid treatment than they had been at the start of the study.

Comparison of tienilic acid with cyclopenthiazide in hyperuricaemic hypertensive patients.

Tienilic acid, a diuretic with uricosuric properties, was compared with cyclopenthiazide, in an open, random-order, within-patient crossover study (3 months on each drug) in 36 hyperuricaemic hypertensive patients. All were on an established dose of cyclopenthiazide; most were also on a beta-blocker which they continued to take in their usual dose. A mean dose of 210 mg of tienilic acid gave the same antihypertensive and diuretic effect as a mean dose of 0.41 mg of cyclopenthiazide. Serum uric acid was very much lower when patients were on tienilic acid (0.29 mmol/l) than on cyclopenthiazide (0.50 mmol/l). Apart from slightly higher serum-chloride and serum-urea during the period on tienilic acid, no major differences in serum-electrolytes, renal-function tests, glucose tolerance, and fasting lipids were observed. Audiometric tests showed that tienilic acid was not ototoxic. S.G.O.T. and S.G.P.T. rose to pathological values in 3 women when they were on tienilic acid, to a lesser extent, in 2 men when they were on cyclopenthiazide. There is no definite evidence that the changes in the transaminases were related to tienilic acid. Some postural hypotension or slight fluid retention occurred during the initial, dose-finding period, and 3 patients had mild indigestion but no patient had to discontinue the trial because of side-effects.

Supersaturation of urine with uric acid and urate: response to a uricosuric diuretic.

In order to assess the possibility that treatment with the uricosuric diuretic ticrynafen (tienilic acid) could lead to UA or MSU crystalluria, the degree of urinary supersaturation with respect to these crystalloids was assessed in persons receiving the diuretic for 1 week, and the results were compared with similar data generated from the use of probenecid. Initially, only probenecid significantly increased the degree of urinary suspersaturation with respect to MSU, and after adjustment of urine pH values to 5.5, probenecid also increased the degree of urinary supersaturation with respect to nonionized UA. At a pH of 5.5, the urine was significantly more supersaturated with nonionized UA after a single dose of probenecid than after ticrynafen (tienilic acid). Ticrynafen never significantly affected the degree of urinary supersaturation with respect to UA or MSU. Neither agent affected small amounts of "colloidal" or "bound" urinary urate. Insofar as the degree of urinary supersaturation with these crystalloids predisposes to crystalluria and calculus formation, ticrynafen (tienilic acid) appears to present no increased risk.

[Cytogenetic study of the mutagenic properties of the repellents dimethyl phthalate and phenoxyacetic acid N,N-diethylamide]. / Tsitogeneticheskoe issledovanie mutagennykh svoistv repellentov dimetilftalata i N,N-diétilamida fenoksiuksusnoi kisloty.

Animal experiments ascertained that the repellent N,N-diethylamide of phenoxyacetic acid (P-203) increases the frequency of chromosomal aberration in the bone marrow cells of mice following its intraperitoneal introduction and also in the cells of a regenerating liver of rats after its repeated skin application. Dimethylphthalate displayed a mutagenic action only with respect to the rats' hepatocytes when applied repeatedly to the skin.

(Vinylaryloxy)acetic acids. A new class of diuretic agents. 1. (Diacylvinylaryloxy)acetic acids.

A series of (diacylvinylaryloxy)acetic acids was synthesized and tested in dogs for saluretic and diuretic activity. Several compounds exhibit a high order of activity, the most active being [2,3-dichloro-4-(2,2-diacetylvinyl)-phenoxy]acetic acid (3). This compound is about three times as potent as [2,3-dichloro-4-(2-methylenebutyryl)-phenoxy]acetic acid (ethacrynic acid) but is qualitatively similar in causing a prompt increase in the excretion of water and in the excretion of sodium and chloride ions in approximately equimolar amounts. Saturation of the double bond of 3 virtually abolishes activity lending support to the hypothesis that the saluresis induced by these compounds, like that of ethacrynic acid, is related at least in part to a chemical reaction with protein-bound sulfhydryl groups. Four mercaptan adducts of 3 were prepared; these probably function as prodrugs in producing saluresis. The adduct with mercaptoacetic acid is as active as 3 itself.

(Vinylaryloxy)acetic acids. A new class of diuretic agents. 2. (4-(3-Oxo-1-alkenyl)phenoxy)acetic acids.

A series of (E)-[4-(3-oxo-1-alkenyl)phenoxy]acetic acids was synthesized and tested in dogs for saluretic and diuretic properties. Several compounds exhibited noteworthy activity, e.g., (E)-[2,3-dichloro-4-(3-oxo-1-butenyl)phenoxy]acetic acid (3a). While possessing only half of the dose potency of ethacrynic acid (2), the active compounds act similarly to this diuretic in causing a prompt increase in the excretion of water and in the excretion of sodium and chloride ions in approximately equimolar amounts. Potassium ion excretion is increased but less markedly than sodium excretion.