Psychopharmacology of a new anxiolytic agent EGYT-3886

Comparison of the effects of deramciclane, ritanserin and buspirone on extracellular dopamine and its metabolites in striatum and nucleus accumbens of freely moving rats

In the present study, we assessed the effect of single graded doses of a putative anxiolytic compound, the 5-HT(2A/C )antagonist, deramciclane fumarate (EGIS-3886), on the dopamine efflux and metabolism in nucleus accumbens and striatum and thus evaluated the dose window for deramciclane to cause adverse effects related to the brain dopaminergic system. Dual probe in vivo microdialysis in freely moving rats was used to compare the effects of graded doses of deramciclane fumarate (3, 10 and 30 mg/kg), 5-HT(2A/C )antagonist ritanserin (1 mg/kg) and a partial 5-HT(1A) agonist buspirone hydrochloride (5 mg/kg) on the extracellular levels of dopamine, 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) in nucleus accumbens and striatum assayed by high performance liquid chromatography with electrochemical detection. The indirect dopamine agonist, D-amphetamine sulfate (2 mg/kg), was used as a positive control. Ritanserin, buspirone and deramciclane 3 and 10 mg/kg had no significant effects on the extracellular dopamine levels in either brain area but deramciclane 30 mg/kg significantly increased accumbal dopamine as well as DOPAC and HVA in both brain areas. As expected, the positive control D-amphetamine significantly increased both striatal and accumbal dopamine levels. The effects of buspirone or the highest deramciclane dose and D-amphetamine on DOPAC and HVA levels were opposite; buspirone and deramciclane increased while D-amphetamine decreased the metabolite levels in both brain areas. The results indicate that a single high dose of deramciclane has the neuroleptic- or buspirone-like effect, particularly in mesolimbic regions. There is at least a 5-fold margin between the anxiolytic and neuroleptic doses of deramciclane in the rat.

Influence of food on the oral bioavailability of deramciclane from film-coated tablet in healthy male volunteers

The effect of a high-fat meal on the oral bioavailability of deramciclane 30 mg tablet was evaluated in 18 healthy male volunteers in a randomised, single dose, two-way crossover study. The drug was administered following an overnight fast or a standardised high-fat breakfast. The plasma concentrations of deramciclane and N-desmethylderamciclane were determined by using a validated HPLC-MS -MS/MS method. An effect of food on the bioavailability was indicated if the 90% confidence interval (CI) for the ratio of geometric means of fed and fasted treatments was not contained in the equivalence limit of 0.8-1.25 for AUC and C(max). The ratios of the mean C(max) and AUC(0-infinity) values of deramciclane were 1.24 (90% CI 1.12-1.38) and 1.31 (90% CI 1.21-1.41) in fed versus fasted subjects, which overlapped but exceeded the equivalence limit. In contrast to the parent compound, the 90% CI of the mean ratios for AUC(0-infinity) and C(max) of N-desmethylderamciclane were within the predefined range. The 24 and 31% increase in C(max) and AUC(0-infinity) of deramciclane, respectively, under fed condition is modest and probably has no clinical significance since it is relatively small compared to the inter-individual variability of these parameters.

Studies of the side chain cleavage of deramciclane in rats with radiolabelled compounds

The pharmacokinetics of deramciclane and especially the fate of its side chain were studied in rats after oral treatment, using (3)H- and (14)C-labelled (ring- or side chain labelled) deramciclane and (14)C-dimethylamino-ethanol ((14)C-DMAE) radioisomers. The labelled compounds were admixed and the total radioactivities of both labels were simultaneously determined. The data obtained from the analysis of the plasma concentration-time curves revealed that an intensive cleavage (30-40%) of the side chain occurred at the ether bond. The core of deramciclane, carrying the ring label, was almost completely eliminated during 24 h, while the elimination of the side chain was very slow (t(1/2)(beta): 99 h). The side chain residue most probably represents dimethylamino-ethanol, but the presence of dimethylglycine (DMG) cannot be excluded. The AUC(0-infinity) and the MRT values of DMAE were found to be much higher than those of the parent compound. In addition to the plasma levels, the time related changes of the tissue concentrations of the radioisomers of deramciclane were analysed both in the brain and the hypophysis. The concentration-time curves have shown similar characteristics to those of the plasma, but higher concentrations were reached in both organs (the highest in the hypophysis). It is postulated that the low rate of formation and elimination of the metabolite(s) (DMAE or DMG) indicates that, due to their endogenous nature, they can be incorporated into choline/acetylcholine or protein synthesis.

Deramciclane inhibits N-methyl-D-aspartate receptor function

Effects of the novel anxiolytic drug deramciclane on excitatory amino acid release and transmembrane Ca(2+) ion flux processes were compared in rat cerebrocortical homogenates containing resealed plasmalemma fragments and nerve endings. Deramciclane (10 microM) significantly inhibited [(3)H]D-aspartate release and transmembrane Ca(2+) flux to N-methyl-D-aspartate in the absence of Mg(2+). By contrast, inhibition of [(3)H]D-aspartate release and transmembrane Ca(2+) flux evoked by 0.1 mM (S)-alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate in the presence of Mg(2+) and 10 microM cyclothiazide by 10 microM deramciclane was not significant. In the presence of N-methyl-D-aspartate receptor antagonists, deramciclane (10 microM) did not inhibit [(3)H]D-aspartate release to N-methyl-D-aspartate. These results suggest an involvement of the inhibition of a presynaptic N-methyl-D-aspartate receptor in the anxiolytic properties of deramciclane.

Inhibition of [3H]D-aspartate release by deramciclane

The effects of the 5-HT2C receptor inverse agonist deramciclane on the gamma-aminobutyric acid (GABA) uptake and excitatory amino acid release processes were compared in rat cerebrocortical homogenates containing resealed plasmalemma fragments and nerve endings. Deramciclane non-competitively inhibited the uptake of [3H]GABA with a Ki value of 13.7 +/- 0.5 microM and partially displaced specifically bound [3H](R,S)-N-[4,4-bis(3-methyl-2-thienyl)-3-butenyl]nipecotic acid ([3H]NNC-328) with high affinity (IC50 = 2.0 +/- 0.7 nM). Depolarization by 4-aminopyridine or by 4-aminopyridine with (S)-alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate [(S)-AMPA] induced the release of [3H]D-aspartate. Deramciclane (10 microM) partially (approximately 50%) inhibited the release of [3H]D-aspartate without affecting [3H]D-aspartate uptake. These results suggest a role for presynaptic inhibition of excitatory amino acid release and GABA uptake in the anxiolytic properties of deramciclane.

Effect of deramciclane, a new 5-HT receptor antagonist, on cholecystokinin-induced changes in rat gastrointestinal function

Recent studies suggested that serotonin receptors may be involved in modulating the actions of cholecystokinin (CCK) in the gastrointestinal tract. The present work was designed to compare the effects of deramciclane, a recently developed serotonin-2 (5-HT2A/2C) receptor antagonist, and lorglumide, a CCK(A) receptor antagonist, on exogenous and endogenous CCK-induced pancreatic enzyme secretion and pancreatic growth, as well as on the emptying of the stomach and the gallbladder. Pancreatic secretory function was tested while CCK release was evoked by diversion of bile-pancreatic juice in rats. Adaptive growth of the pancreas was induced by chronic intragastric administration of camostate, a potent synthetic trypsin inhibitor in rats. Gastric emptying of a noncaloric test meal was investigated in response to intraduodenal intralipid infusion, also in rats. In fasted mice, gallbladder emptying was examined in response to intragastric egg yolk administration. In rats, diversion of bile-pancreatic juice from the duodenum stimulated pancreatic amylase secretion. This action was blocked by deramciclane and by lorglumide. Pancreatic hypertrophy and hyperplasia induced by chronic camostate administration was also suppressed by both the serotonin- and the CCK-receptor antagonists. Intraduodenal administration of intralipid induced a significant delay in gastric emptying. This effect was inhibited by both deramciclane and lorglumide in rats. In mice, intragastric administration of egg yolk elicited an accelerated release of bile from the gallbladder. Prior treatment with either deramciclane or lorglumide abolished this response. Lorglumide was able to inhibit the functional responses elicited by exogenous CCK administration in both pancreas, stomach and gallbladder, while deramciclane was not effective under such circumstances. Our data show that deramciclane inhibited the effects of CCK on pancreatic, gastric and gallbladder function when its endogenous release was stimulated, but did not alter the effects of exogenously administered peptide. These results suggest that serotonin, primarily via 5-HT2A receptors, may modulate CCK-mediated gastrointestinal functions in rats.

Whole-body autoradiography and quantitative organ-level distribution study of deramciclane in rats

The distribution of 3H-labelled deramciclane (EGIS-3886), a new 5-HT2 antagonist with anxiolytic activity, has been investigated by whole-body autoradiography and quantitative organ-level determination after intravenous and oral administration to male and female rats at a dose of 3 mg kg(-1). Pregnant dams were also studied, but by autoradiography only. In the autoradiographic study 32 organs were investigated, while in the quantitative organ-level study the radioactivity in 15 organs were determined. There are no sex differences in the distribution of deramciclane, absorption is rapid, elimination is comparatively fast, no specific organ is targeted, and the accumulation of the compound is very unlikely. Penetration of the blood-brain barrier was complete and extremely fast, a very important feature of a potential anxiolytic drug. There is no penetration of the foetus in pregnant dams. The study demonstrated that deramciclane has advantageous pharmacokinetic properties in rats.

Distribution of deramciclane (EGIS-3886) in rat brain regions

The time related distribution and pharmacokinetics of double-labelled EGIS-3886 (EGIS-3886-phenyl-14C and -ethyl-3H) were studied in the plasma, hypophysis and 14 cerebral regions, including the spinal cord of the rat after a single oral treatment (acute experiments) and after repeated administration of one dose daily for six days (subacute experiments). The tissue levels of EGIS-3886 (deramciclane) were calculated from the simultaneously determined dpm values and the specific activities of the two radioisomers present in the dose administered. EGIS-3886 was rapidly absorbed from the gastrointestinal tract (t(max)=1.0 h). The concentration-time curves in the tissues can be described by a two compartment open model. The 3H-activity could be measured during the whole period of the acute experiment (96 h), whereas 14C-radioactivity fell below the detection limit within 24 h. The AUC(0-96) values for 3H were 10 to 15 times higher than that for 14C. In all samples examined, on the concentration time curves a peak characteristic of enterohepatic cycle can be seen at 12 h. The studies indicated that intact molecules entered brain tissues from the circulation. The results of the subacute experiments indicate that the 14C-labelled EGIS-3886, or its metabolite(s) carrying the tracer, reach an equilibrium as early as on the second to third day, whilst the level of 3H-radioactivity continually increases during the six days of repeated administration. In the subacute experiments the peak concentrations were reached at 0.5 h after the final treatment. However, their values for 3H were higher than in acute experiments. The last tendency was not observed in the case of 14C-tracer. The AUC values of 3H-labelled EGIS-3886 determined in subacute experiments predominated over 14C; the ratios were 50 to 60 in all brain regions. The enterohepatic cycle, seen after a single dose, also operated after repeated dosage. The time related concentrations of EGIS-3886 in the hypophysis were at least two times higher than that in the plasma and the brain tissues. No significant difference was seen in the concentrations of EGIS-3886 in the symmetrical (left and right) regions of the brain.