RESUMO
The previously reported oxytocin antagonist L-371,257 (2) has been modified at its acetylpiperidine terminus to incorporate various pyridine N-oxide groups. This modification has led to the identification of compounds with improved pharmacokinetics and excellent oral bioavailability. The pyridine N-oxide series is exemplified by L-372,662 (30), which possessed good potency in vitro (Ki = 4.1 nM, cloned human oxytocin receptor) and in vivo (intravenous AD50 = 0.71 mg/kg in the rat), excellent oral bioavailability (90% in the rat, 96% in the dog), good aqueous solubility (>8.5 mg/mL at pH 5.2) which should facilitate formulation for iv administration, and excellent selectivity against the human arginine vasopressin receptors. Incorporation of a 5-fluoro substituent on the central benzoyl ring of this class of oxytocin antagonists enhanced in vitro and in vivo potency but was detrimental to the pharmacokinetic profiles of these compounds. Although lipophilic substitution around the pyridine ring of compound 30 gave higher affinity in vitro, such substituents were a metabolic liability and caused shortfalls in vivo. Two approaches to prevent this metabolism, addition of a cyclic constraint and incorporation of trifluoromethyl groups, were examined. The former approach was ineffective because of metabolic hydroxylation on the constrained ring system, whereas the latter showed improvement in plasma pharmacokinetics in some cases.
Assuntos
Oxazinas , Piridinas , Receptores de Ocitocina/antagonistas & inibidores , Administração Oral , Animais , Disponibilidade Biológica , Linhagem Celular , Cromatografia Líquida de Alta Pressão , Cães , Feminino , Humanos , Rim/citologia , Rim/embriologia , Rim/metabolismo , Fígado/metabolismo , Masculino , Espectrometria de Massas , Oxazinas/síntese química , Oxazinas/metabolismo , Oxazinas/farmacocinética , Oxazinas/farmacologia , Gravidez , Piridinas/síntese química , Piridinas/metabolismo , Piridinas/farmacocinética , Piridinas/farmacologia , Ratos , Receptores de Ocitocina/metabolismo , Proteínas Recombinantes/antagonistas & inibidores , Proteínas Recombinantes/metabolismo , Espectrofotometria Ultravioleta , Contração Uterina/efeitos dos fármacos , Útero/efeitos dos fármacos , Útero/fisiologiaRESUMO
From a series of potent cyclic hexapeptide oxytocin (OT) antagonists, a compound that exhibited significant bradykinin (BK) agonist activity was identified. L-366,811 (cyclo[L-proline-D-tryptophan-L-isoleucine-D-pipecolic acid-L-piperazine-2-carboxylic acid-N-Me-D-phenylalanine]) stimulated phosphatidylinositol (PI) turnover in rat uterine slices in vitro (approximately EC50, 2 microM) with a maximal effect (15-fold increase over basal) greater than that obtained for either BK or OT. L-366,811 also elicited dose-related contractions of the isolated rat uterus, producing measurable effects at 100 nM. Several other equally potent OT antagonists from the cyclic hexapeptide structural class were either less potent or inactive as activators of uterine PI turnover or contractility. The stimulatory effects of L-366,811 on uterine PI turnover and contractions were blocked by BK antagonists but not by an arginine vasopressin (AVP)/OT antagonist. In radioligand binding studies, L-366,811 exhibited moderate affinity (IC50, 360 nM) for the [3H]BK binding site in rat uterus, consistent with its potency in the functional models. These results indicate that L-366,811 exhibits BK agonist activity in rat uterus in vitro.
Assuntos
Bradicinina/fisiologia , Ocitocina/antagonistas & inibidores , Peptídeos Cíclicos/farmacologia , Útero/efeitos dos fármacos , Animais , Bradicinina/metabolismo , Feminino , Fosfatos de Inositol/metabolismo , Ratos , Ratos Endogâmicos , Trítio , Contração Uterina/efeitos dos fármacos , Útero/metabolismoRESUMO
L-744,453 ((+/-)3-[4-(1-carboxy-1-(3,4-methylenedioxyphenyl)methoxy)-3,5-diprop ylphenyl methyl]-3H-imidazo[4,5-c]pyridine) is an endothelin (ET) receptor antagonist from a new structural class, the dipropyl-alpha-phenoxyphenylacetic acid derivatives. L-744,453 competitively and reversibly inhibits [125I]-ET-1 binding to Chinese Hamster Ovary cells expressing cloned human ET receptors (K(i)s: hET(A)=4.3 nM; hET(B)=232 nM), and is selective for endothelin receptors compared to other peptide receptors. It is an antagonist of ET-1 stimulated phosphatidyl inositol hydrolysis in rat uterine slices (IC50=220 nM) and exhibits no agonist activity. This compound also inhibits ET-1 stimulated contraction of rat aortic rings with a K(b) value of 50 nM. L-744,453 protects against ET-1 induced lethality in mice after i.v. (AD50=13 mg/kg i.v.) or oral administration. This compound also antagonizes ET-1 induced increases in diastolic blood pressure in conscious normotensive rats (AD50=0.67 mg/kg i.v.) and anesthetized ferrets (AD50=1.6 mg/kg i.v.). L-744,453 is a potent, selective, orally active endothelin antagonist which may be useful in elucidating the role of endothelin in normal and pathophysiological states.
Assuntos
Dioxóis/farmacologia , Antagonistas dos Receptores de Endotelina , Imidazóis/farmacologia , Animais , Disponibilidade Biológica , Pressão Sanguínea/efeitos dos fármacos , Células CHO/efeitos dos fármacos , Células CHO/metabolismo , Cricetinae , Dioxóis/metabolismo , Dioxóis/toxicidade , Cães , Endotelinas/antagonistas & inibidores , Endotelinas/metabolismo , Endotelinas/farmacologia , Feminino , Furões , Humanos , Hidrólise , Imidazóis/metabolismo , Imidazóis/toxicidade , Técnicas In Vitro , Radioisótopos do Iodo , Cinética , Masculino , Camundongos , Contração Muscular/efeitos dos fármacos , Fosfatidilinositóis/metabolismo , Ratos , Ratos Sprague-Dawley , Receptores de Endotelina/metabolismo , Relação Estrutura-AtividadeRESUMO
From a targeted screening effort and medicinal chemistry program, L-368,899 was selected as the first orally-active oxytocin (OT) antagonist to enter clinical trials. In animal studies, L-368,899 was shown to be a potent and selective OT antagonist and was orally bioavailable in rats, dogs and chimpanzees. L-368,899 was further shown to be a potent OT antagonist in pregnant rhesus and to inhibit spontaneous nocturnal uterine contractions. In Phase I human studies, L-368,899 was generally well-tolerated given intravenously and showed significant plasma levels after oral administration. In addition, L-368,899 blocked OT-stimulated uterine activity in postpartum women with a potency similar to that in the pregnant rhesus monkey. More recently, another structural series has been pursued, represented by L-371,257 [1-(1-(4-(N-acetyl-4-piperidinyloxy)-2-methoxybenzoyl)pip eridin-4-yl)- 1,2-dihydro-4(H)-3,1-benzoxazin-2-one]. L-371,257 exhibits high affinity (Ki, 4.6 nM) for human uterine OT receptors with high selectivity vs. human vasopressin receptors. In rat tissues in vitro, L-371,257 is a potent and competitive OT antagonist (pA2, 8.4) and, in vivo, blocks OT-stimulated uterine activity given both i.v. and intraduodenally. L-371,257 highlights the promise of this novel structural class.
Assuntos
Antagonistas de Hormônios/uso terapêutico , Trabalho de Parto Prematuro/tratamento farmacológico , Ocitocina/antagonistas & inibidores , Tocolíticos/uso terapêutico , Animais , Benzoxazinas , Canfanos/administração & dosagem , Canfanos/química , Canfanos/uso terapêutico , Cães , Feminino , Antagonistas de Hormônios/administração & dosagem , Antagonistas de Hormônios/química , Humanos , Técnicas In Vitro , Macaca mulatta , Estrutura Molecular , Trabalho de Parto Prematuro/fisiopatologia , Oxazinas/química , Oxazinas/uso terapêutico , Pan troglodytes , Piperazinas/administração & dosagem , Piperazinas/química , Piperazinas/uso terapêutico , Piperidinas/química , Piperidinas/uso terapêutico , Gravidez , Ratos , Tocolíticos/administração & dosagem , Tocolíticos/química , Contração Uterina/efeitos dos fármacosAssuntos
Oxazinas/farmacologia , Ocitocina/antagonistas & inibidores , Piperidinas/farmacologia , Animais , Antagonistas dos Receptores de Hormônios Antidiuréticos , Benzoxazinas , Disponibilidade Biológica , Feminino , Humanos , Cinética , Estrutura Molecular , Trabalho de Parto Prematuro/tratamento farmacológico , Oxazinas/química , Oxazinas/farmacocinética , Piperidinas/química , Piperidinas/farmacocinética , Gravidez , Ratos , Receptores de Ocitocina/metabolismo , Receptores de Vasopressinas/metabolismo , Contração Uterina/efeitos dos fármacosRESUMO
The vasopressin antagonist, d(CH2)5Tyr(Me)AVP, potently (IC50 = 1.55 nM) inhibited contractions of isolated rat caudal artery rings elicited by vasopressin (AVP), 10 nM (an approximate EC85 concentration of agonist). Antagonism was selective for AVP, as the compound at concentrations up to 1 microM did not block submaximal contractions induced by comparable concentrations of norepinephrine, serotonin or K+. After a short (15 min) exposure to d(CH2)5Tyr(Me)AVP, tissues demonstrated a slow recovery of their normal response to AVP. Recovery was still incomplete following more than 2 hr of repeated washing, indicating that d(CH2)5Tyr(Me)AVP behaved functionally in this tissue as a slowly dissociable antagonist. Examination of the concentration-response to AVP in arterial rings treated with various concentrations of antagonist demonstrated that this compound acts noncompetitively. Although d(CH2)5Tyr(Me)AVP caused a rightward shift in the concentration-response to AVP, the magnitude of the shift was not incremental for incremental changes in the concentration of antagonist. Moreover, a reduction of the maximum response to AVP was superimposed on the nonincremental shift. It is concluded that d(CH2)5Tyr(Me)AVP acts as a potent, selective, slowly reversible and noncompetitive antagonist of AVP elicited contraction of the rat caudal artery.
Assuntos
Arginina Vasopressina/análogos & derivados , Arginina Vasopressina/antagonistas & inibidores , Receptores de Angiotensina/efeitos dos fármacos , Vasoconstrição/efeitos dos fármacos , Animais , Arginina Vasopressina/farmacologia , Artérias/efeitos dos fármacos , Técnicas In Vitro , Masculino , Norepinefrina/farmacologia , Ratos , Ratos Endogâmicos , Receptores de Vasopressinas , Serotonina/farmacologiaRESUMO
8-Hydroxy-2-(di-N-propylamino)tetralin (8-OH-DPAT), a reported serotonin receptor agonist, was found to produce drops both in mean arterial blood pressure (MAP) and heart rate in unanesthetized spontaneously hypertensive rats. The hypotensive episodes were elicited whether the compound was given intraperitoneally (minimum hypotensive dose = 0.02 mg/kg), orally (7.5 mg/kg or intracerebroventricularly (0.014 mg/kg). No bradycardia, however, was elicited following intracerebral infusions of 8-OH-DPAT. The bradycardia and hypotension were moderate in duration (1-4 hr). The serotonin receptor blocking agents cyproheptadine (5 mg/kg i.p.) and methergoline (1.0 mg/kg i.p.) failed to reduce either of the cardiovascular actions of 8-OH-DPAT. Methiothepin (0.5 mg/kg), another serotonin receptor blocker which produces falls in MAP itself, failed to attenuate 8-OH-DPAT-induced hypotension, but did block 8-OH-DPAT-induced bradycardia. 8-OH-DPAT exerts potent hypotensive and bradycardic effects in the unanesthetized spontaneously hypertensive rat. Whether this effect is the result of serotonin receptor activation is not yet clear.
Assuntos
Anti-Hipertensivos , Naftalenos/farmacologia , Tetra-Hidronaftalenos/farmacologia , 8-Hidroxi-2-(di-n-propilamino)tetralina , Administração Oral , Animais , Anti-Hipertensivos/administração & dosagem , Pressão Sanguínea/efeitos dos fármacos , Ciproeptadina/farmacologia , Frequência Cardíaca/efeitos dos fármacos , Injeções Intraperitoneais , Injeções Intraventriculares , Masculino , Metergolina/farmacologia , Metiotepina/farmacologia , Ratos , Ratos Endogâmicos SHR , Tetra-Hidronaftalenos/administração & dosagemRESUMO
In contrast to endothelin-1 (ET-1) and several of its analogues, sarafotoxin S6c (S6c) was a much more potent inhibitor of [125I]-ET-1 binding in rat hippocampus and cerebellum (Ki approximately 20 pM) than in rat atria and aorta (Ki approximately 4500 nM), suggesting the existence of ET-1 receptor subtypes (aorta/atria, ETA; hippocampus/cerebellum, ETB). S6c was a potent activator of PI turnover in hippocampus (EC50 approximately 10 nM) but not atria (EC50 greater than 1 microM), unlike ET-1 which was active in both tissues. S6c, therefore, is a highly selective ETB agonist. Furthermore, S6c was a potent pressor agent in the pithed rat (ED25 mm Hg approximately 0.1 nmoles/kg, i.v.), suggesting that the ETB receptor subtype may be important in cardiovascular function.
Assuntos
Endotelinas/metabolismo , Receptores de Superfície Celular/efeitos dos fármacos , Venenos de Víboras/farmacologia , Animais , Aorta/metabolismo , Sítios de Ligação , Ligação Competitiva , Pressão Sanguínea/efeitos dos fármacos , Cerebelo/metabolismo , Átrios do Coração/metabolismo , Hipocampo/metabolismo , Medula Renal/metabolismo , Fosfatidilinositóis/metabolismo , Ratos , Receptores de Superfície Celular/metabolismo , Receptores de Endotelina , Venenos de Víboras/metabolismoRESUMO
A number of structurally novel cyclic hexapeptides have been characterized as potent and selective oxytocin (OT) antagonists in vitro. As a representative of this class of compounds, L-366,948 [[cyclo(L-prolyl-D-2-naphthylalanyl-L-isoleucyl-D-pipecolyl- L-pipecolyl-D- histidyl)]] exhibited a high binding affinity (Ki, low nanomolar) for OT receptors in rat (uterus and mammary) and primate (pregnant rhesus and human myometrium) tissue with a several hundred-fold binding selectivity vs. rat arginine vasopressin (AVP)-V1 (liver) and AVP-V2 (kidney medulla) receptors. In functional assays, L-366,948 was a pure OT antagonist, blocking both OT-stimulated contraction of the isolated rat uterus (pA2, 8.5) and phosphatidylinositol turnover in uterine slices (IC50, 40 vs. 3 nM OT), with no evidence of partial agonist activity. L-366,948 was comparatively weak as an antagonist of AVP-induced contraction of the isolated rat tail artery (AVP-V1 receptor) and AVP-stimulated adenylate cyclase (AVP-V2 receptor) activity in rat kidney medulla and did not influence prostaglandin F2 alpha- or bradykinin-induced contractions of the isolated rat uterus. L-366,948 and related compounds described in this report represent new experimental tools for the study of the pharmacology and physiology of OT.
Assuntos
Ocitocina/antagonistas & inibidores , Peptídeos Cíclicos/farmacologia , Sequência de Aminoácidos , Animais , Arginina Vasopressina/antagonistas & inibidores , Feminino , Cinética , Masculino , Dados de Sequência Molecular , Peptídeos Cíclicos/metabolismo , Ratos , Ratos Endogâmicos , Trítio , Útero/anatomia & histologia , Útero/efeitos dos fármacosRESUMO
L-659,066 has been characterized as a potent and selective alpha-2 adrenoceptor antagonist. Both in vitro and in vivo, L-659,066 exhibited specificity (comparable to rauwolscine) for alpha-2 over alpha-1 adrenoceptors. Studies comparing L-659,066 with a previously described antagonist, L-657,743, demonstrate that the new compound penetrates the blood-brain barrier only poorly after systemic administration. With a pA2 of 8.44 at alpha-2 adrenoceptors in the isolated rat vas deferens and an IC50 of 3.0 nM against the binding of [3H]rauwolscine to rat cerebrocortical membranes, L-659,066 possessed, respectively, about one-eighth and one-third of the potency of L-657,743. Similar relative potencies were obtained in vivo in pithed rats with regard to blocking peripherally located postjunctional and prejunctional alpha-2 adrenoceptors (L-659,066 = one-seventh and one-fourth of L-657,743, respectively). In tests carried out in vivo with rats for ascertaining alpha-2 adrenoceptor antagonism in the central nervous system--namely, accumulation of cortical dopa and antagonism of mydriasis induced by the alpha-2 agonist, clonidine--L-659,066 had, respectively, less than 1/345th and about 1/5000th of the potency of L-657,743. In mice, L-659,066 had, respectively, approximately 1/29th and 1/1400th of the potency of L-657,743 as an antagonist in vivo of the predominately peripherally mediated inhibition of colonic propulsion caused by clonidine as compared with the mainly centrally mediated antinocisponsive action elicited by the alpha-2 agonist UK 14,304. The foregoing findings are consistent with poor penetration of the blood-brain barrier by L-659,066.(ABSTRACT TRUNCATED AT 250 WORDS)
Assuntos
Quinolizinas/farmacologia , Receptores Adrenérgicos alfa/metabolismo , Antagonistas Adrenérgicos alfa/farmacologia , Animais , Ligação Competitiva , Barreira Hematoencefálica/efeitos dos fármacos , Callitrichinae , Clonidina/farmacologia , Estado de Descerebração , Di-Hidroxifenilalanina/metabolismo , Motilidade Gastrointestinal/efeitos dos fármacos , Masculino , Contração Muscular/efeitos dos fármacos , Ratos , Ratos Endogâmicos , Ducto Deferente/metabolismo , Ioimbina/metabolismoRESUMO
Two cyclic hexapeptides unrelated in chemical structure to oxytocin (OT) were shown in vivo to be antagonists of the contractile action of OT on the uterus. In anesthetized rats challenged with OT (1 micrograms/kg) administered as an i.v. bolus, L-366,682 [cyclo-(L-Pro-D-Trp-L-Ile-D-pipecolic acid-L-pipecolic acid-D-His)] and L-366,948 (D-2-naphthyl-alanine in place of D-Trp) were equipotent with AD50 values of about 100 micrograms/kg i.v. At doses of L-366,682 or L-366,948 causing approximately 90 to 95% block (approximately the AD95 dose) of OT, the duration of action of the antagonists exceeded 145 min. Both compounds exhibited selectivity in the rat, as a dose of either at 300 micrograms/kg i.v. shifted the dose-response for OT-induced uterine contraction to the right by approximately 5-fold but did not affect the dose-response to prostaglandin F2 alpha. Furthermore, neither compound, at a dose of 3 mg/kg i.v., antagonized the action of arginine vasopressin acting at V-1 (pressor effect in pithed rats) or V-2 (antidiuretic) receptors. In conscious, freely moving, pregnant rhesus monkeys, L-366,948 or L-366,682 given i.v. or s.c. were effective antagonists of uterine contractions elicited by an infusion of OT. OT- or arginine vasopressin-like agonist activity was not observed in any of the in vivo models. It is concluded that L-366,682 and L-366,948 act in vivo as reasonably potent, long-acting and selective antagonists at OT receptors in the rat and rhesus uterus.
Assuntos
Ocitocina/antagonistas & inibidores , Peptídeos Cíclicos/farmacologia , Contração Uterina/efeitos dos fármacos , Animais , Feminino , Infusões Intravenosas , Macaca mulatta , Gravidez , Ratos , Ratos EndogâmicosRESUMO
L-754,142, (-)-N-(4-iso-propylbenzenesulfonyl)-alpha-(4-carboxyl-2-n-propy lphenoxy)-3,4- methylenedioxyphenylacetamide, is a potent nonpeptidyl endothelin antagonist (e.g., Ki: cloned human ETA = 0.062 nM: cloned human ETB = 2.25 nM), with high specificity for endothelin receptors. In vitro, L-754,142 is a potent antagonist of ET-1-induced phosphatidyl inositol hydrolysis in Chinese hamster ovary cells expressing cloned human endothelin receptors (IC50: hETA = 0.35 nM; hETB = 26 nM) and of ET-1 induced contractions in rabbit iliac artery rings (pA2 = 7.74) and rat aortic rings (pA2 = 8.7). In vivo, L-754,142 is a potent and specific antagonist of exogenously administered ET-1 or big ET-1, L-754,142 fully protects against ET-1-induced lethality in mice (AD50 = 0.26 mg/kg i.v.). The pressor response to big ET-1 in the anesthetized ferret is blocked by this compound with an ED50 value of 0.019 mg/kg i.v. L-754,142 also blocks the pressor response to big ET-1 in the conscious rat with ED50 values of 0.30 mg/kg i.v. and 0.56 mg/kg p.o. The duration of action of L-754,142 in this rat model is more than 12 hr after an oral dose of 3 mg/kg. In summary, L-754,142 is a potent, orally active ET antagonist with a long duration of action in several in vivo models.
Assuntos
Acetamidas/farmacologia , Antagonistas dos Receptores de Endotelina , Endotelinas/antagonistas & inibidores , Acetamidas/farmacocinética , Administração Oral , Animais , Disponibilidade Biológica , Pressão Sanguínea/efeitos dos fármacos , Células CHO , Cricetinae , Furões , Humanos , Hidrólise , Técnicas In Vitro , Masculino , Camundongos , Contração Muscular/efeitos dos fármacos , Músculo Liso Vascular/efeitos dos fármacos , Músculo Liso Vascular/fisiologia , Fosfatidilinositóis/metabolismo , Coelhos , Ratos , Ratos Sprague-Dawley , Receptores de Endotelina/metabolismoRESUMO
L-366,509, a member of a novel class of nonpeptidyl compounds, has been characterized as an orally active oxytocin (OT) antagonist. L-366,509 exhibits a moderate binding affinity (K(i) values, 370-780 nM) for the rat, rhesus and human uterine OT receptor. L-366,509 also binds to vasopressin receptor subtypes (arginine vasopressin-V1 and V2) with measurable affinity in rat (K(i) values, 25-30 microM) and primate (K(i) values, 2-6 microM) tissues. In rat uterine slices, L-366,509 inhibits (IC50 = 1.6 microM) the stimulation of phosphatidylinositol turnover induced by OT but not bradykinin. In the rat isolated uterus, L-366,509 is a competitive and reversible OT antagonist (pA2 = 7.32). In vivo, L-366,509 given i.v. (10 mg/kg) or intraduodenally (10-50 mg/kg) to rats causes a marked and long-lasting inhibition of OT-stimulated uterine activity. OT antagonist activity in a pregnant rhesus macaque (approximately day 135 gestation) is also observed with L-366,509 after i.v. or p.o. dosing. L-366,509 represents a prototype for a new chemical class of OT antagonists with significant p.o. bioavailability.
Assuntos
Ocitocina/antagonistas & inibidores , Piperidinas/química , Piperidinas/farmacologia , Compostos de Espiro/química , Compostos de Espiro/farmacologia , Administração Oral , Animais , Feminino , Humanos , Técnicas In Vitro , Injeções Intravenosas , Macaca mulatta , Masculino , Fosfatidilinositóis/metabolismo , Gravidez , Ensaio Radioligante , Ratos , Ratos Sprague-Dawley , Estimulação Química , Contração Uterina/efeitos dos fármacos , Útero/efeitos dos fármacos , Útero/metabolismoRESUMO
Structure-activity studies on the oxytocin antagonist 1 (L-371,257) have identified a new series of high affinity, receptor-selective OT antagonists in which the N-acetyl-4-piperidinyl ether terminus in 1 has been replaced with a 1-(aryl)ethoxy group.
Assuntos
Oxazinas/farmacologia , Ocitocina/antagonistas & inibidores , Piperidinas/farmacologia , Administração Oral , Animais , Benzoxazinas , Disponibilidade Biológica , Feminino , Humanos , Ratos , Relação Estrutura-AtividadeRESUMO
Structure-activity studies on the oxytocin antagonist 1 (L-371,257; Ki = 9.3 nM) have led to the identification of a related series of compounds containing an ortho-trifluoroethoxyphenylacetyl core which are orally bioavailable and have significantly improved potency in vitro and in vivo, e.g., compound 8 (L-374,943; Ki = 1.4 nM).