METHOD FOR TREATING OBSTRUCTIVE AIRWAY DISEASES

Abstract: A method for the treatment of obstructive airway diseases utilizing 11-substituted 5,11-Dihydro-6H-Pyrido[2,3-b] [1,4] Benzodiazepin-6-ones.

Description: METHOD FOR TREATING OBSTRUCTIVE AIRWAY DISEASES The research which resulted in the making of the invention described herein was funded, in part, by a grant received from the Federal Government, specif¬ ically Grant No. 1 ROl HL 31219 from the National Institutes of Health. 11-substituted 5,ll-dihydro-6H-pyrido[2,3-b] [1,4] benzodiazepin-6-ones, such as 11-aminoacetyl- 5,ll-dihydro-6H-pyrido[2,3-6] [1,4] benzodiazepin-6- ones or the non-toxic pharmacologically acceptable salts thereof, are tricyclic compounds having the structural formula wherein R.. is hydrogen or alkyl of 1 to 4 carbon atoms, R 2 is hydrogen chlorine or methyl, and R_ and R . are each alkyl of 1 to 5 carbon atoms or, together with each other and the nitrogen atom to which they are attached, camphidino, pyrrolidino, morpholino, piperidino, methyl-piperidino, ethyl-piperidino, piperazino, N 1 -methyl-piperazino, N'-ethyl- piperazino, N'-hydroxyethyl-piperazino, N'-benzyl- piperazino, N'-methylbenzyl-piperazino or hexamethyle- neimino. Of these compounds, 5,11-dihydro-ll-[(4'-methyl- l-piperazinyl)-acetyl] -6H-pyrido [2,3-b][l,4] benzodiazepin-6-one, is exemplary of these compounds, and has been extensively described in the scientific literature. It is presently used in man to signifi¬ cantly reduce gastric acid and pepsinogen secretion. The compound is Pirenzepine, and reference to its preparation and use may be found in "Selective muscarinic receptor antagonists" by R. Hammer and A. Giachetti (Trends In Pharmaceutical Sciences, 1984, Elsevier Publications, Cambridge) , and United States Patent No. 3,660,380, the disclosure of which is incorporated herein in toto. The structure of this compound is: Pirenzepine is an antimuscarinic agent which has been demonstrated to be an effective inhibitor of gastric secretion and is currently available in Europe as an anti-ulcer medication. It is thought to specifically antagonize a subtype of muscarinic receptors; it inhibits gastric secretion but not other muscarinic activities (i.e., gastric emptying, esophageal motility) and neither mydriasis nor tachy¬ cardia occur with its administration. It has been reported to be relatively ineffective (compared to atropine) in smooth muscle preparations from the intestine and vasculature. Grass, and Skorodin (Am. Rev. Respir. Dis. 129:856, 1984) describe the problems of side effects with atropine as a bronchodilator either inhaled or administered parenterally. Quaternary ammonium analogs, such as atropine methonitrate and ipratro- piu bromide, which are poorly absorbed, limit side effects but must be administered by aerosol. SUMMARY OF THE INVENTION Contrary to what has been reported, we have discovered these compounds, exemplified by piren¬ zepine, to inhibit vagally-induced bronchoconstric¬ tion in mammals. The compounds of the present invention, and specifically pirenzepine have the advantage of atropine of being able to be adminis¬ tered orally without concurrent side effects due to selectivity for a receptor subtype which appears to be limited to the vagal bronchoconstructive pathway (and the vagal secretary pathway in the stomach) . Thus, compounds of the present invention are better choices of antimuscarinic agents for airways obstruc¬ tive disease because they are potent inhibitors of vagally - induced bronchoconstriction and can be given orally without crossing the blood brain barrier or causing other side effects. In order to demonstrate the use of the compounds as potential therapeutic agents in asthma and other airway obstructive diseases, a number of tests were conducted in rabbit models. Thus, studies were conducted to demonstrate in vivo inhibition of vagally-induced bronchoconstriction in the rabbit (Example I) , and to demonstrate the presence of Ml receptors in rabbit lung (Example II) . EXAMPLE I Randomly bred New Zealand rabbits of both sexes, weighing 2 to 3 kg, were anesthetized by intravenous injection with thiopental sodium. Light surgical anesthesia was maintained by supplements of a mixture of chloralose and urethane. After tracheostomy, an endotracheal tube was connected to a pheumotach to measure breathing frequency and flow. Transpulmonary pressure was obtained by placing a polyethylene catheter in the right pleural space and connecting it to a differential pressure transducer (the other arm of which was connected to a small bore tap off of the endotracheal tube) . Volume was determined by elec¬ trical integration of flow. Pulmonary resistance was calculated from raw data signals of transpulmonary pressure, volume, and flow using a Z80 CPU computer. A saline filled polyethylene catheter was placed in the thoracic aorta, threaded via the femoral artery in order to measure phasic aortic pressure and heart rate. The animals were paralyzed with succinyl- choline and mechanically ventilated. The cervical vagus nerve was isolated bilaterally and transected. The distal cut ends of the cervical vagi were electrically stimulated simultaneously for 1 minute duration (40 Hz frequency, 0.3 msec pulse duration, 10 volts intensity) , and the maximum increase in pulmonary resistance and decrease in heart rate determined. Two stimulations were performed 3 minutes apart. Intravenous infusions of antagonist drug, either atropine or pirenzepine, were given in 5 increasing concentrations and vagal stimulation repeated. Stimulations were performed at 6 and 9 minutes after each drug infusion was begun. Six animals received atropine and 6 animals pirenzepine. For each dose of antagonist drug, the percent inhibi¬ tion of the change in pulmonary resistance or heart rate induced by vagal stimulation was determined and an inhibition curve constructed. The dose of drug required to antagonize by 50% the effect of vagal stimulation on pulmonary resistance and heart rate (IC 50) was calculated from the curves. The results appear in the following table: - € ■ Vagal Increase in Vagal Decrease Pulmonarv Resistance in Heart Rate Atropine (n=6) 0.6 nmol/kg/min 1.6 nmol/kg/min Pirenzepine (n=6) 10.1 nmol/kg/min 420 nmol/kg/min Pirenzepine:Atropine Ratio 17 280 These data demonstrate that the classical muscarinic antagonist, atropine, differs only 2.5 fold in its capacity to inhibit the two vagally induced alterations. In contrast, pirenzepine shows a differential inhibitory activity, with a 42-fold greater inhibitory activity on bronchoconstriction as compared to the decrease in heart rate. These data support the concept that pirenzepine is a subtype selective muscarinic antagonist and that the Ml (pirenzepine sensitive) receptors are present in the vagal pathway for bronchoconstriction but not in the vagal pathway for cardiac slowing. Pirenzepine is only 17-fold less potent than atropine when acting on the Ml receptor but is 280-fold less potent than atropine on the cardiac muscarinic receptors (M2) . EXAMPLE II To demonstrate the presence of Ml receptors in 3 rabbit lung, ligand binding studies with H-pirenze- pine binding in homogenized peripheral lung tissue were performed. Scatchard analysis of the binding curves indicate the presence of a high-affinity receptor for pirenzepine with a dissociation constant (Kα,) of 5 nM. Maximum binding- (Bmax) values comoared to those for the nonsubtype selective antagonist 3 H-QNB indicates that the high affinity pirenzepine receptor represents greater than half of the muscar¬ inic receptors present in the peripheral lung (pre¬ cise percentage is currently being determined) . Inhibition studies in which pirenzepine and atropine 3 are used to displace H-QNB yield IC50 (concentration giving 50% displacement) values of 4 and 0.2 nM for pirenzepine and atropine, respectively. This pirenze¬ pine: atropine ratio of 20 for inhibitory potency correlates well with our in vivo functional data showing that pirenzepine is approximately 17-fold less potent than atropine in inhibiting vagally- induced bronchoconstriction. Thus, while we have illustrated and described the preferred embodiments of our invention, it is to be understood that this invention is capable of variation and modification, and we therefore do not wish to be limited to the precise terms set forth, but desire to avail ourselves of such changes and alterations which may be made for adapting the invention to various usages and conditions. Accord¬ ingly, such changes and alterations are properly intended to be within the full range of equivalents, and therefore within the purview, of the following claims. Having thus described our invention and the manner and process of making and using it, in such full, clear, concise, and exact terms so as to enable any person skilled in the art to which it pertains, or with which it is more nearly connected, to make and use the same:

Claims: WE CLAIM: 1. A method for inhibiting bronchoconstriction in a mammal comprising adminis¬ tering to said mammal an affective inhibitory amount of a compound of the formula wherein R. is hydrogen or alkyl of 1 to 4 carbon atoms, R„ is hydrogen chlorine or methyl, and . ~ and R. are each alkyl of 1 to 5 carbon atoms or, together with each other and the nitrogen atom to which they are attached, camphidino, pyrrolidino, morpholino, piperidino, methyl-piperidino, ethyl-piperidino, piperazino, N'-methyl-piperazino, N 1 -ethyl-pipera- zino, N'-hydroxyethyl-piperazino, N'-benzyl-piper- azino, N'-methylbenzyl-piperazino or hexamethyle-nei- mino or a nontoxic and pharmaceutically acceptable salt thereof. 2. The method of Claim 1 wherein the compound is 5,11-dihydro-ll-[ (4'-methyl-l-piperazinyl)- acetyl]-6H-pyrido-[2,3-b] [1,4] benzodiazapin-6-one or a nontoxic and pharmaceutically acceptable salt thereof. 3. The method of Claim 1 wherein the compound is 5,ll-dihydro-5-methyl-ll-[(4'-methyl-1•-pipera- zinyl)-acetyl]-6H-pyrido[2,3-b] [l,4]benzodiazepin-6- one or a nontoxic and pharmaceutically acceptable salt thereof. 4. The method of Claim 1 wherein the compound is 11-[(di-n-butylamino)-acetyl] 5,ll-dihydro-6H- pyrido[2,3-b] [1,4]benzodiazepin-6-one or a nontoxic and pharmaceutically acceptable salt thereof. 5. The method of Claim 1 wherein the compound is 5,11-dihydro-ll-[(4*- hydroxyethyl-1'-pipera- zinyl)-acetyl]-6H-pyrido[2,3-b] [1,4]benzodiazepin-6- one or a nontoxic and pharmaceutically acceptable salt thereof. 6. The method of Claim 1 wherein the compound is 5,11-dihydro-ll-[ (1'-piperazinyl)-acetyl]-6H- pyrido[2,3-b] [1,4]benzodiazepin-6-one or a nontoxic and pharmaceutically acceptable salt thereof. 7. The method of Claim 1 wherein the compound is 5,11-dihydro-ll-(dimethylamino-acetyl)-5-methy1- 6H-pyrido[2,3-b] [1,4]benzodiazepin-6-one or a nontox¬ ic and pharmaceutically acceptable salt thereof. 8. The method of Claim 1 wherein the compound is 5,11-dihydro-ll-[ (2'-methyl-1-piperidino)- acetyl]-6H-pyrido-[2,3-b] [1,4] benzodiazapin-6-one or a nontoxic and pharmaceutically acceptable salt thereof. 9. The method of Claim 1 wherein the compound is 5,ll-dihydro-ll-[ (2*-ethyl-1-piperidino)-acetyl]- 6H-pyrido-[2,3-b] [1,4] benzodiazapin-6-one or a nontoxic and pharmaceutically acceptable salt there¬ of. 10. The method of Claim 1 wherein the compound is 5,ll-dihydro-5-methyl-ll-[ (2'-methyl-1-piperi- dino)-acetyl]-6H-pyrido-[2,3-b] [1,4] benzodiazapin-6- one or a nontoxic and pharmaceutically acceptable salt thereof.

Inventors: BLOOM JOHN W, HALONEN MARILYN, LAWRENCE LOWELL J, YAMAMURA HENRY I, BLOOM, JOHN, W., HALONEN, MARILYN, LAWRENCE, LOWELL, J., YAMAMURA, HENRY, I.
Applicants: UNIVERSITY PATENTS INC, UNIVERSITY PATENTS, INC.
Application year: 1986
Main classification: A61K31
IPC codes: A61K31