Satoshi Okanishi

Possible site of action of TAK-637, a tachykinin NK1 receptor antagonist, on the micturition reflex in guinea pigs

TAK-637((aR,9R)-7-[3,5-bis(trifluoromethyl)benzyl]-8,9,10, 11-tetrahydro-9-methyl-5-(4-methylphenyl)-7H-[1,4]diazocino[2,1-g] [1,7]naphthyridine-6,13-dione) is a novel tachykinin NK(1) receptor antagonist that has been shown to inhibit the micturition reflex in guinea pigs. The aim of this study was to clarify its mechanism of action in guinea pigs. TAK-637 inhibited the spinal vesico-vesical reflex induced by electrical stimulation of the proximal cut end of the pelvic nerve in spinal animals, but not bladder contractions induced by electrical stimulation of the distal cut end of the nerve. Furthermore, TAK-637 had no effect on carbachol- or electrical field stimulation-induced contractions of isolated bladder muscle strips in an organ bath, whereas drugs used for abnormally frequent micturition inhibited both contractions. These results suggest that TAK-637 inhibits the micturition reflex by acting, at least in part, on the spinal cord, and its mechanism of action clearly differs from those of antimuscarinics or spasmolytics.

Effects of TAK-637, a tachykinin receptor antagonist, on the micturition reflex in guinea pigs

The effects of a new tachykinin NK(1) receptor antagonist, (aR, 9R)-7-[3,5-bis(trifluoromethyl)benzyl]-8,9,10, 11-tetrahydro-9-methyl-5-(4-methylphenyl)-7H-[1,4]diazocino[2,1-g] [1, 7]naphthyridine-6,13-dione (TAK-637), on the micturition reflex were compared with those of drugs used for abnormally frequent micturition or incontinence. TAK-637 showed a characteristic effect on the distension-induced rhythmic bladder contractions in guinea pigs. The systemic administration of TAK-637 decreased the number but not the amplitude of the distension-induced rhythmic bladder contractions. A similar effect was observed in animals in which the spinal cord had been severed. TAK-637 also inhibited the micturition reflex induced by topical application of capsaicin onto the surface of bladder dome. From these results, it is concluded that TAK-637 inhibits sensory transmissions from the bladder evoked by both physiological and nociceptive stimuli by blocking tachykinin NK(1) receptors, possibly at the level of the spinal cord. On the other hand, the other drugs such as oxybutynin, tolterodine, propiverine, and inaperisone showed no effects on the frequency of the distension-induced rhythmic bladder contractions but decreased the contraction amplitude. Therefore, TAK-637 may represent a new class of drugs, which would be effective for abnormally frequent micturition without causing voiding difficulties due to decreased voiding pressure.

Effects of TAK-637, a tachykinin receptor antagonist, on lower urinary tract function in the guinea pig.

The effects of TAK-637 ((aR,9R)-7-[3,5-bis(trifluoromethyl)benzyl]-8, 9,10,11-tetrahydro-9-methyl-5-(4-methylphenyl)-7H-[1,4]diazocino[2 , 1-g][1,7]naphthyridine-6,13-dione), a novel tachykinin NK(1) receptor antagonist, on the micturition reflex in guinea pigs were studied in comparison with those of anti-pollakiuria agents. Cystometry was performed under urethane anesthesia. TAK-637 increased the volume threshold with a minimum effective dose of 0.03 mg/kg, i.v. without affecting voiding pressure. Oxybutynin, tolterodine, propiverine and inaperisone also increased the volume threshold in urethane-anesthetized guinea pigs, but they decreased voiding pressure, although the effect of propiverine was not statistically significant. A structurally unique tachykinin NK(1) receptor antagonist, (+/-)-CP-99,994 ((+/-)-(2S, 3S)-3-(2-methoxybenzylamino)-2-phenylpiperidine), increased the volume threshold with a minimum effective dose of 0.3 mg/kg, i.v. TAK-637 increased the volume threshold with a minimum effective dose of 0.01 mg/kg, p.o. in unanesthetized guinea pigs. These results indicate that TAK-637 may be useful as pharmacotherapy for detrusor overactivity without decreasing voiding pressure or causing voiding difficulties.

Characteristics of TRK-130 (Naltalimide), a Novel Opioid Ligand, as a New Therapeutic Agent for Overactive Bladder

We characterized TRK-130 (N-[(5R,6R,14S)-17-(cyclopropylmethyl)-4,5-epoxy-3,14-dihydroxymorphinan-6-yl]phthalimide; naltalimide), an opioid ligand, to clarify the therapeutic potential for overactive bladder (OAB). In radioligand-binding assays with cells expressing human µ-opioid receptors (MORs), δ-opioid receptors (DORs), or κ-opioid receptors (KORs), TRK-130 showed high selectivity for MORs (Ki for MORs, DORs, and KORs = 0.268, 121, and 8.97 nM, respectively). In a functional assay (cAMP accumulation) with cells expressing each human opioid receptor subtype, TRK-130 showed potent but partial agonistic activity for MORs [EC50 (Emax) for MORs, DORs, and KORs = 2.39 nM (66.1%), 26.1 nM (71.0%), and 9.51 nM (62.6%), respectively]. In isovolumetric rhythmic bladder contractions (RBCs) in anesthetized guinea pigs, TRK-130 dose-dependently prolonged the shutdown time (the duration of complete cessation of the bladder contractions) (ED30 = 0.0034 mg/kg i.v.) without affecting amplitude of RBCs. Furthermore, TRK-130 ameliorated formalin-induced frequent urination at doses of higher than 0.01 mg/kg p.o. in guinea pigs under the freely moving condition. Meanwhile, TRK-130 showed only a negligible effect on the gastrointestinal transit at doses of up to 10 mg/kg s.c. in mice. These results indicate that TRK-130 is a potent and selective human MOR partial agonist without undesirable opioid adverse effects such as constipation and enhances the storage function by suppressing the afferent limb of the micturition reflex pathway, suggesting that TRK-130 would be a new therapeutic agent for OAB.

Novel 3-phenylpiperidine-4-carboxamides as highly potent and orally long-acting neurokinin-1 receptor antagonists with reduced CYP3A induction.

The synthesis and biological evaluation of a series of novel 3-phenylpiperidine-4-carboxamide derivatives are described. These compounds are generated by hybridization of the substructures from two types of tachykinin NK(1) receptor antagonists. Compound 42 showed high metabolic stability and excellent efficacy in the guinea-pig GR-73637-induced locomotive activity assay at 1 and 24h after oral administration. It also exhibited good pharmacokinetic profiles in four animal species, and a low potential in a pregnane X receptor induction assay.

Physical dependence-producing properties of tetrapeptide acylhydrazide analogs of enkephalin in rats

Abstract The physical dependence-inducing properties of four systematically potent analgesic tetrapeptide acylhydrazide analogs of enkephalin were evaluated in rats. When H-Tyr-D-Ala-Gly-Phe-NHNHCO-(CH 2 ) 2 CH 3 (EK-159) and H-Tyr-D-Ala-Gly-MePhe-NHNHCO-CH 2 CH 3 (EK-209) were withdrawn after repeated administration, the animals did not lose weight. In addition, these compounds could not substitute for morphine in morphine-dependent rats. When treatment with H-Tyr-D-Met(O)-Gly-MePhe-NHNHCO-CH 2 CH 3 (EK-272) and H-Tyr-D-Met(O)-Gly-MePhe- NHNHCO-CH 3 (EK-333) was stopped, the animals lost body weight, indicating physical dependence. EK-272 and EK-333 substituted, to some extent, for morphine in morphine-dependent rats. The naloxone challenge test revealed the physical dependence liability of EK-209, EK-333, morphine and pentazocine. The degree of physical dependence was greatest with EK-333, followed in decreasing order by morphine, pentazocine and EK-209.