Abstract:
A restenosis inhibiting agent for the treatment or prevention of restenosis after percutaneous transluminal coronary angioplasty which comprises a pharmaceutically effective amount of a compound of the following general formula or a pharmaceutically acceptable salt thereof as an active ingredient: ##STR1## wherein R is an imidazolyl group, a thiazolyl group or a pyridyl group, n is an integer of 1 or 2, and m is an integer of 1 to 4.

Description:
This is a continuation of application Ser. No. 07/703,714 filed May 21, 1991 abandoned, which is a continuation of application Ser. No. 07/485,716 filed Feb. 27, 1990 abandoned. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to a post-angioplasty restenosis inhibiting agent. More particularly, the invention relates to a restenosis inhibiting agent for the treatment or prevention of restenosis after percutaneous transluminal coronary angioplasty. 
     BACKGROUND OF THE INVENTION 
     Percutaneous transluminal coronary angioplasty (hereinafter, referred to briefly as PTCA) is a relatively new approach to the treatment of ischemic heart diseases and technically involves mechanical dilatation of the stenosed region of the coronary artery by means of a balloon. However, it is known that PTCA is not a radical therapy for atherosclerotic lesions of the coronary arteries, and the mechanically dilated part of the coronary arteries undergoes restenosis within several post-angioplasty months with a frequency of about 40 percent. For controlling this restenosis, antiplatelets, anticoagulants, etc. have heretofore been tried, but drugs that would be sufficiently effective clinically are not available as yet. 
     SUMMARY OF THE INVENTION 
     As a result of an extensive investigation to obtain a compound having an excellent inhibitory effect on post-PTCA restenosis, the inventors of the present invention found that a compound of the following general formula or a pharmaceutically acceptable salt thereof: ##STR2## wherein R is a an imidazolyl group, a thiazolyl group or a pyridyl group, n is an integer of 1 or 2, and m is an integer of 1 to 4, is effective in inhibiting post-PTCA restenosis of the coronary artery, and have completed the present invention. 
     The above-mentioned compound of general formula (I) and salt thereof are known to inhibitors of thromboxane A 2  synthesis, and are effective in ischemic heart disease as disclosed in U.S. Pat. Nos. 4,665,188 and 4,777,257. However, it is a novel finding that these compounds have an inhibitory effect on post-PTCA restenosis. 
     The present invention is therefore directed to a post-PTCA restenosis inhibiting agent comprising a pharmaceutically effective amount of a compound of the general formula (I) or a pharmaceutically acceptable salt thereof as an active ingredient. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The post-PTCA restenosis inhibiting agent of the invention comprises, as aforesaid, a compound of general formula (I) or a pharmaceutically acceptable salt thereof as an active ingredient. The salt is any of pharmaceutically acceptable salts, for example, acid addition salts with inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, etc., or organic acids such as fumaric acid, tartaric acid, maleic acid, succinic acid, etc., and salts, involving the carboxyl group thereof, with alkali metals such as sodium, potassium, etc. or alkaline earth metals such as calcium, magnesium and so on. In the compound of the formula (I), 6-(1-indazolylmethyl)-5,6,7,8-tetrahydronaphthalene-2-carboxylic acid and salts thereof are preferred. 
     The safety of the compound (I), inclusive of salts thereof, has been established in an acute toxicity study in which the compound (I) or a salt thereof was administered orally to rats and its LD 50  value determined. 
     The compound (I) or the salt thereof can be processed into various dosage forms by the established pharmaceutical procedures using known excipients, diluents and/or carriers, such as lactose, corn starch, hydroxypropyl cellulose, magnesium stearate and the resulting preparations, which may be tablets, powders, capsules, injections, etc., can be administered, for example, by the oral, subcutaneous, intramuscular or intravenous route. 
     The oral dosage, for instance, of the compound (I) or salt thereof is generally in the range of 100 to 1,000 mg/day for an adult human. 
     It has been confirmed clinically that the compound (I) and the salts thereof have an excellent inhibitory effect on post-PTCA restenosis. Therefore, the post-PTCA restenosis inhibiting agent of the present invention is useful in the treatment or prevention of post-PTCA restenosis. 
     The present invention is now illustrated in greater detail by the following examples but it should be understood that the present invention is not limited thereto. 
     EXAMPLE 1 
     In 18 patients with angina pectoris in whom elective PTCA was indicated, 6-(1-imidazolylmethyl)- 5,6,7,8-tetrahydronaphthalene-2-carboxylic acid hydrochloride hemihydrate (hereinafter, referred to as Compound A) was administered orally in a dose of 200 mg three times a day after each meal (600 mg/day) pre-angioplasty, beginning about three days before PTCA, and post-angioplasty for 3 months (treated group). Coronary angiography was performed before, immediately after, and 3 months after PTCA. Based on the coronary angiographic findings, inhibition of restenosis of the right coronary artery, left anterior descending artery and left circumflex artery was evaluated, by site of lesion, according to the criteria in Table 1 shown below. Further, based on the results of the evaluation, overall efficacy evaluation by individual patient was made. 
     TABLE 1 
     Criteria for evaluation of coronary angiographic findings 
     In regard to luminal diameter: 
     1. Excellent post-angioplasty course: unchanged or expanded 
     2. Good post-angioplasty course: a decrease in luminal diameter of less than 50% 
     3. Poor post-angioplasty course: a decrease in luminal diameter of 50% or more and less than 100% 
     4. Worse post-angioplasty course: a decrease in luminal diameter of 100% or progression of stenosis as compared with pre-PTCA condition 
     As controls (control group), placebo was similarly administered to 15 patients with angina pectoris in whom effective PTCA was indicated and coronary angiography was performed before and after PTCA. 
     In both of the treated and control groups, calcium antagonists, viz. nifedipine and diltiazem, antianginal drugs, viz. ISDN and nicorandil, and antiarteriosclerotic agents, viz. elastase, etc. were used concurrently as necessary as shown in Table 2 below. However, there was no significant difference (X 2  test) between the two groups in the use of concomitant drugs, as in other patient characteristics. 
     
                       TABLE 2______________________________________         Control   TreatedConcomitant Drug         Group     Group     Test______________________________________Nifedipine    14        15Diltiazem     1         1ISDN          15        18Nicorandil    3         7         Not                             significantElastase      5         0Others        4         4______________________________________ 
    
     The results are shown in Tables 3 and 4 below. 
     
                       TABLE 3______________________________________Evaluation of coronary angiographic findingsby site of lesion -       Num-       ber       ofSite        Lesions Excellent                        Good   Poor Worse______________________________________Right  Control   5      2      0      3    0Coronary  groupArtery Treated   8      3      4      0    1  groupLeft   Control  20      3      9      5    3Anterior  groupDescend-  Treated   9      4      3      1    1ing    groupArteryLeft   Control   1      0      1      0    0Circum-  groupflex   Treated  11      2      7      1    1Artery group(Note) Control  26      5      10     8    3Total  group            (19.2%)                          (57.7%)  Treated  28      9      14     2    3  group            (32.1%)                          (82.1%)______________________________________ (%): Cumulative % Note: Wilcoxon test P = 0.100 
    
     
                       TABLE 4______________________________________Overall Efficacy Evaluation, by Individual Patient(based on coronary angiographic findings)                                Number ofExcellent    Good      Poor   Worse  Patients______________________________________Control 0        7         5    3      15group            (46.7%)Treated 7        7         3    1      18group   (38.9%)  (77.8%)______________________________________ (%): Cumulative % Wilcoxon test P = 0.010 Fisher test (with regard to excellent ratings) P = 0.009 
    
     As clearly seen from the above tables, it was clinically confirmed that in both evaluations by lesion and by patient, a superior inhibitory effect on post-PTCA restenosis was obtained in the treated group than in the control group. 
     EXAMPLE 2 
     The LD 50  values of Compound A by probit method are shown in Table 5 below. 
     
                       TABLE 5______________________________________LD.sub.50 values (rats, per oral)   LD.sub.50 (mg/kg)   Male  Female______________________________________   2438  1994______________________________________ 
    
     While the invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof.