(Phenylpiperazinyl-butyl)oxindoles as selective 5-HT7 receptor antagonists.

A series of potent 5-hydroxytryptamine 7 (5-HT 7) ligands has been synthesized that contain a 1,3-dihydro-2 H-indol-2-one (oxindole) skeleton. The binding of these compounds to the 5-HT 7 and 5-HT 1A receptors was measured. Despite the structural similarity of these two serotonin receptor subtypes, several derivatives exhibited a high selectivity to the 5-HT 7 receptor. According to the structure-activity relationship observations, compounds unsubstituted at the oxindole nitrogen atom and containing a tetramethylene spacer between the oxindole skeleton and the basic nitrogen atom are the most potent ligands. Concerning the basic group, besides the moieties of the 4-phenylpiperazine type, halophenyl-1,2,3,6-tetrahydropyridines also proved to be 5-HT 7 receptor-ligands. Because of halogen substitution on the aromatic rings, good metabolic stability could be achieved. A representative of the family, 3-{4-[4-(4-chlorophenyl)-piperazin-1-yl]-butyl}-3-ethyl-6-fluoro-1,3-dihydro-2 H-indol-2-one ( 9e') exhibited selective 5-HT 7 antagonist activity ( K i = 0.79 nM). The in vivo pharmacological potencies of these 5-HT 7 receptor-ligands were estimated by the conflict drinking (Vogel) and the light-dark anxiolytic tests.

[Effect of tofisopam on CYP3A4 enzyme activity on human recombinant 3A4 supersome]. / Tofisopam hatása a humán rekombináns CYP3A4 szuperszóma enzim aktivitására.

Tofisopam is an anxiolytic agent of the BZD group, chemically 1(3-4 dimethoxyphenyl)-4methyl-5-ethyl-7,8 dimethoxy-5H-2,3-benzodiazepine. TZP differs from the traditional 1,4-benzodiazepines regarding the positions of the nitrogen atoms. Three clinical cases were reported where tofisopam increased the blood level of immunosuppressive agent leading clinically relevant adverse drug reaction and necessitating reduction of the dose of the drugs or discontinuation of the administration of tofisopam. The administered immunosuppressive agent is a substrate of the CYP3A4 system, so the effect of tofisopam on the CYP3A4 enzyme was investigated in vitro using human recombinant CYP3A4 supersome. Benzyoxy-4-(trifluoromethyl)-coumarin (BFC) was used as substrate. Tofisopam in 0.1, 0.25, 0.5, 0.75, 1 and 5 micromol/l concentrations inhibited dose dependently the enzyme activity. Activity inhibition rates were 4%, 29%, 40%, 56%, 61% and 94%, respectively and the IC50 was 0.8 micromol/l. The IC50 of positive control substance ketoconazole was 0.03 micromol/l. In in vitro experiments the inhibitory effect of tofisopam was lower than that of ketoconazole (potent CYP3A4 inhibitor) with an order of magnitude. According to the in vitro results it could be concluded that tofisopam is an inhibitor of CYP3A4 but to clarify the clinical importance of this inhibition further human clinical data are needed.

The glycine transporter-1 inhibitors NFPS and Org 24461: a pharmacological study.

The in vitro and in vivo pharmacology of two glycine transporter-1 (GlyT1) inhibitors, N[3-(4'-fluorophenyl)-3-(4'-phenylphenoxy)-propyl]sarcosine (NFPS) and R,S-(+/-)N-methyl-N-[(4-trifluoromethyl)phenoxy]-3-phenyl-propylglycine (Org 24461), was studied. NFPS and Org 24461 inhibited the uptake of [3H]glycine in hippocampal synaptosomal preparation with IC(50) values of 0.022 and 2.5 microM. Neither NFPS nor Org 24461 (0.1 microM) showed significant binding to alpha-1, alpha-2, and beta-adrenoceptors, D(1) and D(2) dopamine receptors, and 5-HT(1A) and 5-HT(2A) serotonin receptors in membranes prepared from rat brain or to cloned 5-HT(6) and 5-HT(7) receptors. At 10 microM concentrations, binding affinity was measured for NFPS to 5-HT(2A) and 5-HT(2C) serotonin receptors and alpha-2 adrenoceptors and for NFPS and Org 24461 to 5-HT(7) serotonin receptors. Glycine (0.1 mM) and sarcosine (5 mM) increased [3H]glycine efflux from superfused rat hippocampal slices preloaded with [3H]glycine. NFPS and Org 24461 (0.1 mM) did not influence [3H]glycine efflux, however, they inhibited glycine-induced [3H]glycine release. These findings indicate that NFPS and Org 24461 selectively inhibit glycine uptake without being substrates of the transporter protein. Several antipsychotic tests were used to characterize antipsychotic effects of NFPS and Org 24461 in vivo. These compounds did not alter apomorphine-induced climbing and stereotypy in a dose of 10 mg/kg p.o. in mice and did not induce catalepsy in a dose of 10 mg/kg i.p. in rats. The ID(50) values of NFPS were 21.4 mg/kg and higher than 30 mg/kg i.p. for inhibition of phencyclidine (PCP)- and D-amphetamine-induced hypermotility in mice and these values were 2.5 and 8.6 mg/kg i.p. for Org 24461. NFPS and Org 24461 did not exhibit anxiolytic effects in light-dark test in mice, in the meta-chlorophenylpiperazine (mCPP)-induced anxiety test (minimal effective dose or MED was higher than 3 mg/kg i.p.) and in the Vogel conflict drinking test in rats (MED was higher than 10 mg/kg i.p.). Both NFPS and Org 24461 (1-10 mg/kg i.p.) reversed PCP-induced changes in EEG power spectra in conscious rats. These data support the view that GlyT1 inhibitors may have potential importance in treatment of negative symptoms of schizophrenia.

Effects of EGIS-7625, a selective and competitive 5-HT2B receptor antagonist.

Our aim was to specify the 5-HT(2) subtype selectivity of EGIS-7625 (1-benzyl-4-[(2-nitro-4-methyl-5-amino)-phenyl]-piperazine), a new 5-HT(2B) ligand, in receptor binding studies and characterize its pharmacology at 5-HT(2A), 5-HT(2B) and 5-HT(2C) receptors in in vivo experiments and in isolated organs, in vitro. EGIS-7625 had high affinity for recombinant human 5-HT(2B) receptors (pK(i) = 9.0) but much weaker affinity for 5-HT(2A) and 5-HT(2C) receptors (pK(i) = 6.2 and 7.7, respectively). In the classic 5-HT(2B) test, EGIS-7625 produced a concentration-related parallel rightward shift in the concentration-response relationship for the 5-HT-induced smooth muscle constriction in rat stomach fundus strips with a pA(2) of 9.4. On the other hand, EGIS-7625 was a weak competitive antagonist at 5-HT(2A) receptors as it shifted 5-HT-induced concentration-response curves to the right at high concentrations (pA(2) = 6.7) in rabbit pulmonary artery strips. The m-chlorophenylpiperazine-induced hypomotility and hypophagia was only partially attenuated by EGIS-7625 even at a dose of 30 mg/kg i.p. while mianserin, a non-selective 5-HT antagonist was almost fully effective in these tests at 3 mg/kg i.p., suggesting weak antagonistic effect of EGIS-7625 at neuronal 5-HT(2C) receptors, in vivo. In conclusion, EGIS-7625 is a potent, selective and competitive 5-HT(2B) antagonist that seems to be a good research tool for the separation of the functional roles of vascular 5-HT(2A) and 5-HT(2B) receptors.