The pharmacokinetics of [3H]1-[1-(2-thienyl)cyclohexyl]piperidine (TCP) in Sprague-Dawley rats

Using adult male Sprague-Dawley rats, we examined the blood protein binding and pharmacokinetics of the potent phencyclidine (PCP) receptor ligand 1-[1-(2-thienyl)cyclohexyl]piperidine (TCP). The average percentage of unbound [3H]TCP in rat serum was 42 +/- 6% and the [3H]TCP blood to plasma ratio was 0.98 +/- 0.03 (mean +/- SD, n = 5 in both studies). For the pharmacokinetic studies, [3H]TCP and 1 mg/kg unlabeled TCP were administered as an iv bolus dose. The average [3H]TCP elimination half-life was 2.1 hr. In contrast, total radioactivity in the plasma had a much longer half-life, suggesting much slower metabolite elimination. The average distribution volumes were 27 +/- 17, 15.6 +/- 6.2, and 5.6 +/- 3.0 liters/kg for V beta, Vss, and Vc, respectively. Total body and renal clearance values were 132 +/- 45 and 1.1 +/- 0.4 ml/min/kg, respectively. When TCP pharmacokinetic parameters were compared to PCP pharmacokinetic data in rats from a previous study, a strikingly similar pharmacokinetic profile was found. These data indicated that TCP and PCP are equivalent, from a pharmacokinetic point of view, and that the higher pharmacological potency of TCP over PCP is probably due to receptor-mediated differences.     

Identification of human cytochrome P450 isoforms involved in the metabolism of S-2-[4-(3-methyl-2-thienyl)phenyl]propionic acid.

1. To identify the cytochrome P450 (CYP) isoenzymes responsible for the major metabolic pathways of S-2-[4-(3-methyl-2-thienyl)phenyl] propionic acid (S-MTPPA) in man, the metabolism of S-MTPPA was examined using human liver microsomes and microsomes containing cDNA-expressed CYP isozymes (CYP1A2, 2A6, 2B6, 2C9-Arg, 2C9-Cys, 2C19, 2D6-Val, 2E1 and 3A4). 2. S-MTPPA was mainly oxidized to the 5-hydroxylated metabolite of the thiophene ring (MA6) with human liver microsomes in the presence of NADPH. The formation of MA6 was inhibited by SKF 525-A, suggesting that CYP plays role in the formation of MA6. 3. Eadie-Hofstee plots for the 5-hydroxylation of S-MTPPA in the range 5-100 microM were linear for all samples studied, suggesting that the formation of MA6 by human liver microsomes follows simple Michaelis-Menten kinetics. Apparent Vmax = 1.42+/-0.64 nmol/min/mg protein; Km = 12+/-5 microM. 4. Among the CYP inhibitors examined (alpha-naphthoflavone, sulphaphenazole, omeprazole, quinidine and troleandomycin), sulphaphenazole (a CYP2C9 inhibitor) showed the most potent inhibitory effect on the 5-hydroxylation of S-MTPPA by human liver microsomes. 5. When incubated with microsomes containing cDNA-expressed CYP isozymes, S-MTPPA was substantially oxidized to MA6 only by CYP2C9. 6. These results suggest that formation of the major metabolite of S-MTPPA, MA6, in human liver microsomes is catalysed predominantly by a single CYP isoenzyme, namely CYP2C9.     

Identification of human cytochrome P450 isoforms involved in the metabolism of S-2-[4-(3-methyl-2-thienyl)phenyl]propionic acid

1. To identify the cytochrome P450 (CYP) isoenzymes responsible for the major metabolic pathways of S-2-[4-(3-methyl-2-thienyl)phenyl] propionic acid (S-MTPPA) in man, the metabolism of S-MTPPA was examined using human liver microsomes and microsomes containing cDNA-expressed CYP isozymes (CYP1A2, 2A6, 2B6, 2C9-Arg, 2C9-Cys, 2C19, 2D6-Val, 2E1 and 3A4). 2. S-MTPPA was mainly oxidized to the 5-hydroxylated metabolite of the thiophene ring (MA6) with human liver microsomes in the presence of NADPH. The formation of MA6 was inhibited by SKF 525-A, suggesting that CYP plays role in the formation of MA6. 3. Eadie-Hofstee plots for the 5-hydroxylation of S-MTPPA in the range 5-100 μM were linear for all samples studied, suggesting that the formation of MA6 by human liver microsomes follows simple Michaelis-Menten kinetics. Apparent V_max = 1.42±0.64 nmol/min/mg protein; K_m = 12±5 μM. 4. Among the CYP inhibitors examined (α-naphthoflavone, sulphaphenazole, omeprazole, quinidine and troleandomycin), sulphaphenazole (a CYP2C9 inhibitor) showed the most potent inhibitory effect on the 5-hydroxylation of S-MTPPA by human liver microsomes. 5. When incubated with microsomes containing cDNA-expressed CYP isozymes, S-MTPPA was substantially oxidized to MA6 only by CYP2C9. 6. These results suggest that formation of the major metabolite of S-MTPPA, MA6, in human liver microsomes is catalysed predominantly by a single CYP isoenzyme, namely CYP2C9.     

In vivo metabolism of 2-[1'-phenyl-3'-(3-chlorophenyl)-2'-propenylyden]hydrazino-3-methyl-4(3H)-quinazolinone in rats.

The aim of this study was to investigate by HPLC the in vivo metabolism of 2-[1'-phenyl-3'-(3-chlorophenyl)-2'-propenylyden]hydrazino-3-methyl-4(3H)-quinazolinone as a substrate, and as a model compound in rats. The substrate was dissolved in DMSO/water (1:4) and administered intraperitoneally at a dose of 100 mg/kg in a volume of approximately 0.1 mL. Blood samples were taken before and 30 min, 1.5, 3, 6, 9, 11, 30 and 48 h after i.p. drug administration. The chromatographic separation of the substrate and its metabolites was performed using a stainless steel Novopak C18 column (150 x 4.6 mm i.d., 5-microm particle size). The optimal composition of the mobile phase was reached by introducing different mixtures of pure acetonitrile and water in a linear gradient system. Following the biotransformation of this compound, 2-hydrazino-3-methyl-4(3H)-quinazolinone (M1) and 3-(3-chlorophenyl)-1-phenylprop-2-en-1-one (M2) derivatives were identified together with substrate by comparing them to reference standards using HPLC-UV/DAD. In addition, the composition of these metabolites and substrate was confirmed by LC-MS in plasma.     

Novel piperidine derivatives. Synthesis and anti-acetylcholinesterase activity of 1-benzyl-4-[2-(N-benzoylamino)ethyl]piperidine derivatives

A series of 1-benzyl-4-[2-(N-benzoylamino)ethyl]piperidine derivatives was synthesized and evaluated for anti-acetylcholinesterase (anti-AChE) activity. Substituting the benzamide with a bulky moiety in the para position led to a substantial increase in activity. Introduction of an akyl or phenyl group at the nitrogen atom of benzamide dramatically enhanced the activity. The basic quality of the nitrogen atom of piperidine appears to play an important role in the increased activity, since the N-benzoylpiperidine derivative was almost inactive. We found that 1-benzyl-4-[2-(N-[4'-(benzylsulfonyl) benzoyl]-N-methylamino]ethyl]piperidine hydrochloride (21) (IC50 = 0.56 nM) is one of the most potent inhibitors of acetylcholinesterase. Compound 21 showed an affinity 18,000 times greater for AChE than for BuChE. At a dose of 3 mg/kg, 21 produced a marked and significant increase in acetylcholine (ACh) content in the cerebral vortex and hippocampus of rats. Compound 21 was chosen for advanced development as an antidementia agent.     

Piperazine-based CCR5 antagonists as HIV-1 inhibitors. II. Discovery of 1-[(2,4-dimethyl-3-pyridinyl)carbonyl]-4- methyl-4-[3(S)-methyl-4-[1(S)-[4-(trifluoromethyl)phenyl]ethyl]-1-piperazinyl]- piperidine N1-oxide (Sch-350634), an orally bioavailable, potent CCR5 antagonist

Truncation of the original piperidino-2(S)-methyl piperazine lead structure 2, from a family of muscarinic antagonists, gave compound 8 which has improved selectivity for the HIV-1 co-receptor CCR5 over muscarinic receptors. Further optimization for pharmacokinetic properties afforded Sch-350634 (1), a prototypical piperazine-based CCR5 antagonist, which is a potent inhibitor of HIV-1 entry and replication in PBMCs. The title compound (1) has excellent oral bioavailability in rat, dog, and monkey.     

N-[1-(2-benzo[b]thiophenyl)Cyclohexyl]- piperidine (BTCP) exerts cocaine-like actions on drug-maintained responding in rats.

The effects of N-[1-(2-benzo[b]thiophenyl)cyclohexyl]- piperidine (BTCP), a phencyclidine derivative that acts as a potent dopamine reuptake inhibitor, were examined on cocaine self-administration in rats. The effects of BTCP (0, 4, 8, 16, and 32 mg/kg, i.p.) on cocaine self-administration were tested against cocaine doses on both the ascending (0.0625 mg/infusion) and descending (0.25 mg/infusion) limb of the dose-response function. BTCP decreased self-administration of the 0.25-mg cocaine dose in a dose-dependent manner. A 16-mg/kg dose of BTCP that strongly suppressed self-administration of the 0.25-mg cocaine dose increased the intake at the 0.0625-mg dose of cocaine. Moreover, cocaine and BTCP pretreatments produced similar patterns of decreases in self-administration of cocaine on the descending limb of the dose-response function. The results suggest that BTCP has cocaine-like actions and produces a leftward shift of the dose-response curve for cocaine self-administration, indicating that the phencyclidine analog may substitute under certain conditions for the reinforcing effects of cocaine in self-administering rats.     

Studies of thioamides and their derivatives. VIII. Products of decomposition of quaternary salts of 1-[alpha-alkylthio-p-dimethyl- amino)benzylidene]piperidine and 1-[alpha-alkylthio-(p-trialkyl- ammonio)benzylidene]piperidine

Products of decomposition of eight quaternary salts, derivatives of 1-[alpha-alkylthio-(p-dimethylamino)benzylidene]-piperidinium, in water, ethanol, pyridine and glacial acetic acid were investigated. IR and UV spectra of the obtained decomposition products were measured, and the compounds were tested for cytostatic activity.     

Intracellular metabolism of the antiherpes agent (S)-1-[3-hydroxy-2-(phosphonylmethoxy)propyl]cytosine.

(S)-1-[3-Hydroxy-2-(phosphonylmethoxy)propyl]cytosine (HPMPC) is an antiviral phosphonate nucleotide analogue that displays activity against a range of herpesviruses. Anion exchange high performance liquid chromatography analysis of the 60% methanol extract from [14C]HPMPC-treated cells reveals the formation of three major metabolites. Two of these were identified as phosphorylated forms of HPMPC, HPMPC phosphate, and HPMPC diphosphate, by liberation of HPMPC upon acid digestion and coelution with synthetic standards on high performance liquid chromatography. The third metabolite, which is resistant to alkaline phosphatase cleavage but sensitive to phosphodiesterase, is proposed to be an HPMPC phosphate adduct. In herpes simplex virus-1-infected cells the same three metabolites are detected, at concentrations comparable to those in uninfected cells. When HPMPC is removed from the medium, the concentrations of the metabolites in cells decrease slowly, with half-lives of approximately 6, 17, and 48 hr for HPMPC phosphate, HPMPC diphosphate, and the HPMPC phosphate adduct, respectively. HPMPC diphosphate inhibits herpes simplex virus-1 and -2 DNA polymerases with a lower Ki than that for DNA polymerase alpha, and enzyme inhibition is competitive in each case. The formation and the persistence of HPMPC phosphates in cells and the selective inhibition of viral DNA polymerases by HPMPC diphosphate can explain why cells pretreated with HPMPC remain refractory to viral infection even long after HPMPC is removed from the medium.     

Studies on monocyclic beta-lactam antibiotics. IV. Synthesis and antibacterial activity of (3S,4R)-3-[2-(2-aminothiazol-4-yl)-(Z)-2-(O-substituted oxyimino)acetamido]-4-methyl-1- (1H-tetrazol-5-yl)-2-azetidinones

The synthesis and in vitro activity of the 3-(O-substituted oxyiminoacetamido)-2-azetidinones (IV) possessing a tetrazole moiety at N-1 position are described. The introduction of lipophilic functions into the oxyimino moiety gave in some good activity against staphylococci, but decreased activity against Gram-negative bacteria. In contrast, the introduction of hydrophilic functions such as carboxycyclobutane resulted in strong activity against Gram-negative bacteria including Pseudomonas aeruginosa, and no or very small activity against the staphylococci.     

New broad-spectrum cephalosporins with anti-pseudomonal activity. II. Synthesis and antibacterial activity of 7 beta-[2-acylamino-2-(4-hydroxyphenyl)acetamido]-3-[ (1-methyl-1H-tetrazol-5-yl)thiomethyl]ceph-3-em-4-carboxylic acids

The influence of the chirality of the 7-acyl side chain and of various N-acyl moieties (A-CO-) on the in vitro activity of 7 beta-[2-acylamino-2-(4-hydroxyphenyl)acetamido ]-3-[(1-methyl-1H-tetrazol-5-yl)thiomethyl]ceph-3-em-4-carboxylic acids (6) was investigated. A cephalosporin having a 7-acyl side chain of S-configuration (6r) was only weakly active against Staphylococcus aureus and Klebsiella pneumoniae and was inactive against the other species tested. Among the various N-acyl moieties in the cephalosporins having a 7-acyl side chain of the R-configuration, the 4-hydroxypyridine-3-carbonyl moiety, unsubstituted or substituted with 5-bromo and/or 6-alkyl groups and the 4-hydroxy-1,5-naphthyridine-3-carbonyl moiety, unsubstituted or substituted with a 6-methyl and a 6-methoxy group gave the most active compounds. N-Ethylation of the 4-hydroxy-1,5-naphthyridine-3-carbonyl derivative and the 4-hydroxypyridine-3-carbonyl derivative (6p, 6q) resulted in a decrease of the in vitro activity.     

1-(4-羟基苯基)-2-[1-甲基-3-(4-羟基苯基)丙氨基]乙酮盐酸盐对离体蛙心的影响

目的　研究 1- (4 -羟基苯基 ) - 2 - [1-甲基 - 3- (4 -羟基苯基 )丙氨基 ]乙酮盐酸盐对 β -受体的作用。 方法　用斯氏法制备青蛙离体心脏标本 ,用BL - 4 10生物机能实验仪记录心脏收缩活动。结果　β -受体激动剂异丙肾上腺素对离体蛙心有非常明显的兴奋作用 ,10ng·ml-1浓度时可增加离体蛙心脏收缩张力 199.2 9%± 6 9.6 9% (n =8) ;1- (4 -羟基苯基 ) -2 - [1-甲基 - 3- (4 -羟基苯基 )丙氨基 ]乙酮盐酸盐饱和上清药液 2 0 %～ 10 0 % ,对离体蛙心脏亦有明显兴奋作用 ,可分别增加离体蛙心脏收缩张力 81.4 3%± 34.4 4 %、6 0 .5 3%± 2 0 .18%、74 .5 3%± 32 .75 %、74 .34%± 39.6 9%、6 0 .91%± 2 7.73% (n =8) ,但未见明显的剂量效应关系。结论　 1- (4 -羟基苯基 ) - 2 - [1-甲基 - 3- (4 -羟基苯基 )丙氨基 ]乙酮盐酸盐对 β -受体具有激动作用。