Abstract:
The present invention aims at providing a drug which is highly effective in improving decline of mental functions such as disorientation, which are the major symptoms of dementia such as Alzheimer type dementia or cerebrovascular dementia, as well as general side symptoms such as decreased spontaneity, contact disturbances, motivation, emotional disturbances, abnormal behaviors and disturbances in activity of daily living. The agent for improving dementia of the present invention comprises N-(2,6-dimethylphenyl)-2-(2-oxo-1-pyrrolidinyl)acetamide or a salt thereof as an active ingredient.

Description:
This is a continuation of application Ser. No. 08/302,047, filed Sep. 7, 1994, now abandoned, which is a continuation of application Ser. No. 08/163,727, filed Dec. 9, 1993, now abandoned which is a continuation application of Ser. No. 07/876,095, filed Apr. 30, 1992 now abandoned. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to an agent for improving dementia which contains N-(2,6-dimethylphenyl)-2-(2-oxo-1-pyrrolidinyl) acetamide (hereinafter, referred to as compound A) represented by the following formula (I): ##STR1## or a salt thereof as an active ingredient. 
     BACKGROUND OF THE INVENTION 
     In developed countries including Japan, United States and European countries, the number of patients with dementia has been rapidly increasing with the sudden increase in aged population. Since there is no effective therapeutics for this disease, it is a serious social problem to treat and attend on these patients. Under these circumstances, a number of drugs have been examined in order to develop an effective remedy for dementia. However, no drug which is clinically usable therefor has been found out hitherto. 
     On the other hand, it is known that compound A is effective in prolonging the survival time upon a decrease in blood oxygen level and in relieving failure of memory due to cerebropathy, as described in JP-B-62-5404 (the term &#34;JP-B&#34; as used herein means an &#34;examined Japanese patent publication&#34;) (corresponding to U.S. Pat. No. 4,341,790). However, there has been never reported that the compound A is clinically usable for improving the symptoms of dementia. 
     SUMMARY OF THE INVENTION 
     The present inventors have found out that the administration of the compound A to patients with dementia such as Alzheimer type dementia or cerebrovascular dementia causes excellent effects of improving the symptoms of these types of diseases, which had never been expected from the conventional therapeutics, thus completing the present invention. 
     The present invention relates to an agent for improving dementia which contains compound A or a salt thereof as an active ingredient. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Demetia relating to the present invention can be mainly classified into Alzheimer type dementia and cerebrovascular demetia. Alzheimer type dementia may be classified into senile dementia and Alzheimer type disease. It is expected that compound A exerts excellent effects on these diseases. 
     The compound A may be administered either orally or parenterally (for example, intravenously) in a dose of from 60 to 900 mg/day per adult (in the case of oral administration). Examples of preparations containing compound A include tablets, capsules, pills, emulsions, suspensions, fine subtilaes and injection. These preparations may be formulated by a known pharmaceutical techniques with the use of common additives (for example, fillers, binders (hydroxypropylcellulose, etc.), ingredient (lactose, cornstarch, etc.). 
     The compound A has a high safety. When orally administered to male and female mice, it showed acute toxicities (LD 50 ) of 2,005 mg/kg and 1,940 mg/kg, respectively. Thus it has been clinically confirmed that compound A is highly safe. 
     The compound A is highly effective in improving a decline in mental functions such as disorientation (place, time), which are the major symptoms of dementia, as well as general side symptoms such as decreased spontaneity, emotional disturbances, contact disturbances, abnormal behaviors, disturbances in activity of daily living and motivation. Accordingly, the compound A is a very excellent agent for improving dementia. 
    
    
     The present invention is further explained in detail hereinafter by the following Examples, but the present invention is not limited to these examples. 
     EXAMPLE 1 
     300 mg/day of compound A was orally administered for 8 to 12 weeks to 5 patients (excepting cerebrovascular dementia based on Hachinski cerebro-ischemic score) who showed encephalatrophy or ventricular enlargement in CT (computed tomography) or MRI (magnetic resonance image) and thus were diagnosed as Alzheimer type dementia based on clinical symptoms specified in DSM-III-R (Handbook for the Diagnosis of Mental Diseases prepared by U.S. Society of Psychopathy). Before the administration and 4 weeks, 8 weeks and 12 weeks thereafter, the dementia conditions of these patients were clinically evaluated by typical methods for evaluating dementia, namely, classification of severity by fast staging (hereinafter, referred to simply as Fast), criteria for evaluating cognitive functions (modified GBS), mini-mental state examination (hereinafter, referred to simply as MMS), Hasegawa&#39;s simplified dementia scale (hereinafter, referred to simply as HDS) and Crichton&#39;s criteria for evaluating behaviors. Based on the data thus obtained, the final global improvement rate (hereinafter, referred to simply as FGIR) and the overall safety rate (hereinafter, referred to simply as OSR) of each case were evaluated. 
     Table 1 shows the results of FGIR and OSR, while Table 2 shows the number of improved or worsened patients for each symptom. Tables 3 and 4 show each a patient showing improvement in FGIR. 
     
                       TABLE 1______________________________________Evaluation  No. of Case       I     II  III IV  V   VI______________________________________FGIR   5                         2       2       1OSR    5                     5 FGIR! I:    remarkably improved.  II:   improved.  III:  slightly improved.  IV:   unchanged.  V:    slightly aggravated.  VI:   aggravated. OSR!  I:    no safety problems.  II:   negligible safety problems        existed.  III:  safety problems existed.  IV:   significant safety problems        existed.______________________________________ 
    
     
                       TABLE 2______________________________________Improved or Worsened Item (symptom)       No. of Case                 Improved Worsened______________________________________Decreased spontaneity         5           2        0Emotional disturbance         5           2        1Contact disturbance         5           2        0Decline in mental         5           2        0functionAbnormal behaviors         5           1        1Disturbance in activity         5           1        1of daily living______________________________________ 
    
     
                                           TABLE 3__________________________________________________________________________List of Alzheimer type dementia symptoms                               FAST/Hachinski                               Cerebro-ischemic         Complication/                      Pretreatment/                               Score/MMS/Sex/AgeDose/Time         Suffering Period/CT/MRI                      Combined Drug                               Hasegawa&#39;s Scale                                        FGIR/OSR__________________________________________________________________________Female/80300 mg/12 weeks         iron-deficiency anemia/                      no/no    5/1/(11)/13.0                                        improved/         2 years/encephalatrophy:       no safety         slight, and ventricular        problem         enlargement: moderate__________________________________________________________________________                  Evaluation of Cognitive Function                  Improvement Severity                  4 week                      8 week                          12 week                              (pre                                  4 week                                      8 week                                          12 week)__________________________________________________________________________FAST                               ( 5 4   4   4 )**Orientation:space                  III III III ( 2 1   1   1 )time                   III III III ( 4 3   3   3 )Memory:private information before outbreak                  IV  IV  IV  ( 3 3   3   3 )private information after outbreak                  IV  IV  IV  ( 3 3   3   3 )Motivation:endogenous motivation  III II  II  ( 3 2   1   1 )exogenous motivation   III III III ( 3 2   2   2 )Consideration:suitability of judgement                  III III III ( 2 1   1   1 )development of conversation                  IV  IV  IV  ( 3 3   3   3 )Emotion:variation of emotional expression                  IV  IV  IV  ( 1 1   1   1 )self-suppression of emotional expression                  III III III ( 2 1   1   1 )Communication:precision of speaking  III III III ( 3 2   2   2 )rationality of speaking                  IV  IV  IV  ( 1 1   1   1 )Pre     4 week        8 week             12 weekMMS   11 →   14 →        5  →             16HDS   13.0 →   14.5      →        15.5           →             17.5__________________________________________________________________________ **: Degree of disorientation II: improved. III: slightly improved. IV: unchanged. 
    
     
         Crichton&#39;s Criteriafor Behavior (modified)Change               Side Effect/No.* Pre      12 Weeks                Abnormal Clinical Data                             Comment__________________________________________________________________________1.   1    →         1      no/no        Getting to be able to handle a2.   3    →         2                   gas water heater.3.   2    →         2                   Making purchases with a memo4.   3    →         2                   note, as previously, but never5.   2    →         1                   purchasing any unnecessary goods.6.   2    →         2                   Frankly stating her opinion. →7.   2    →         1                   Sometimes boycotting the test8.   1    →         1                   (refusing writing sentences in9.   1    →         1                   MM, &#34;I&#39;m weak in writing&#34;).10.  2    →         1                   The medicine of the invention11.  1    →         1                   was administered from the first                             examination, after confirming                             her husband that she had been in                             the same conditions for past 2 to                             4 weeks. Although no change was                             shown in HDS or MMS score, IADL                             suggested obvious improvement.                             Improvement in these points can                             be hardly evaluated by the                             methods employed here.__________________________________________________________________________ *: 1: walking. 2: orientation. 3: conversation. 4: interpersonal contact. 5: unrest. 6: changing clothes. 7: eating. 8: incontinence. 9: sleeping. 10: objective mood. 11: subjective mood. 
    
     
                                           TABLE 4__________________________________________________________________________List of Alzheimer type dementia symptoms                            FAST/Hachinski                            Cerebro-ischemic        Complication/                    Pretreatment/                            Score/MMS/Sex/AgeDose/Time        Suffering period/CT/MRI                    Combined Drug                            Hasegawa&#39;s Scale                                    FGIR/OSR__________________________________________________________________________Female/73300 mg/9 weeks        hepatic function                    Elen    5/4/18/15.5                                    improved/        disorder/3 years/                    (Trade Mark,    no safety        encephalatrophy:                    Indeloxazine    problem        slight, and ventricular                    Hydrochloride)        enlargement: slight                    (3T)/no__________________________________________________________________________             Evaluation of Cognitive Function             Improvement Severity             4 week                 8 week                     12 week                         (pre                             4 week                                 8 week                                     12 week)__________________________________________________________________________FAST                          (5      5   )**Orientation:space             IV  IV      ( 2 2   2   )time              IV  IV      ( 4 4   4   )Memory:private information before outbreak             IV  IV      ( 3 3   3   )private information after outbreak             IV  IV      ( 3 3   3   )Motivation:endogenous motivation             III III     ( 3 2   2   )exogenous motivation             II  II      ( 3 1   1   )Consideration:suitability of judgement             IV  IV      ( 1 1   1   )development of conversation             II  II      ( 3 1   1   )Emotion:variation of emotional expression             III III     ( 3 2   2   )self-suppression of emotional expression             IV  IV      ( 2 2   2   )Communication:precision of speaking             IV  IV      ( 2 2   2   )rationality of speaking             IV  IV      ( 1 1   1   )Pre     8 weekMMS   18 →   21HDS   15.5 →   18.5__________________________________________________________________________ **: Degree of disorientation II: improved. III: slightly improved. IV: unchanged. 
    
     
         Crichton&#39;s Criteriafor Behavior (modified)Change            Side Effect/No.*    Pre       12 Weeks             Abnormal Clinical Data                         Comment__________________________________________________________________________1.  1   →         1   no/no       Beginning to give lessons in2.  3   →         3               penmanship to grandchildren3.  2   →         2               spontaneously (feeling tired4.  2   →         1               before the administration).5.  1   →         1               HDS and MMS show little change.6.  1   →         1               Moderate improvement was observed7.  1   →         1               even in a drug-rest period8.  1   →         1               between 4 and 8 weeks.9.  1   →         1               In this case, spontaneousness and10. 2   →         1               positiveness were remarkably11. 2   →         1               improved.                         No examination was made after 9                         week. Having no contact with                         her family, it seems that the                         disorders in behaviors have                         never been worsened.__________________________________________________________________________ *: 1: walking. 2: orientation. 3: conversation. 4: interpersonal contact. 5: unrest. 6: changing clothes. 7: eating. 8: incontinence. 9: sleeping. 10: objective mood. 11: subjective mood. 
    
     As the above Tables clearly show, compound A is effective in improving mental symptoms (for example, decreased spontaneity, emotional disturbances, contact disturbances, decline in mental functions, abnormal behaviors) of patients with Alzheimer type dementia. Evaluating the improvement effect on these symptoms, the overall improvement rate of compound A is 40% (2 (improvement case) per 5 all tried case). Also, as apparently from the Table 1, the mental symptoms of 2 cases per 5 cases were not worsened. Furthermore, any side effect was not observed for all tried patients. 
     Generally, a main characteristic points of patients with Alzheimer type dementia is just that the symptoms of this disease become worse and worse, and any medicines have never showed clinical effects to this disease. 
     Therefore, these clinical effect of compound A to Alzheimer type dementia, that is, the improvement effect on the symptoms, the suppresing effect on getting worse relating to the symptoms and the effect relating to the safety have never been expected from the clinical effect of convertional medicines for this disease. 
     EXAMPLE 2 
     150 to 450 mg/day of compound A was orally administered for 8 weeks to 145 patients with cerebrovascular dementia who showed infarction or hemorrhagic lesions in CT (computed tomography) and scored less than 22 points in Hasegawa&#39;s simplified dementia scale (HDS) frequently employed in the simplified diagnosis for dementia. The clinical conditions of each patient were evaluated with HDS, which is frequently used for evaluating the effects of nootropic agents, before the initiation of the administration and 4 weeks and 8 weeks thereafter. Based on these data, the final global improvement rate (FGIR) and the overall safety rate (OSR) were determined. 
     Table 1 shows the results of FGIR and OSR, while Table 2 shows the improvement rate (%) for each symptom. 
     
                       TABLE 1______________________________________No. of Case      I      II    III  IV  V    DP______________________________________FGIR 145       7      37  57   33  5    6   72.7                                        improvement                                       rate (%)*!OSR  145       134    8   3    0   --   0   97.9                                        safety rate                                       (%)**!*improvement rate = (I + II + III)/139 × 100**safety rate = (I + II)/145 × 100 FGIR!    I: remarkably improved. II: moderately improved.     III: slightly improved. IV: unchanged.     V: aggravated. DP: dropped out. OSR!     I: no safety problem.     II: negligible safety problems existed.______________________________________ 
    
     
                       TABLE 2______________________________________                    Improved  WorsenedSymptom       No. of Case                    (%)       (%)______________________________________Decreased spontaneity         138        59.4      0.0Emotional disturbance         135        54.1      1.5Contact disturbance         122        38.5      0.8Decline in mental function         139        46.0      2.2Abnormal behaviors         49         49.0      10.2______________________________________ 
    
     As the above Tables clearly show, compound A is effective in improving mental symptoms (for example, decreased spontaneity, emotional disturbances, contact disturbances, decline in mental functions, abnormal behaviors) of patients with cerebrovascular dementia. The overall improvement rate determined by generally evaluating these results in 72.7%, showing excellent effects. 
     In general, it is considered that the effects of medicinal treatments on cerebrovascular dementia are inferior to those on sequela of cerebrovascular disorders, namely, the preceding stage of the former. However, compound A achieves a high overall improvement rate (72.7%) for cerebrovascular dementia which is comparable to, or even exceeds, the overall improvement rate (about 70%) of conventional nootropic agent for the sequela of cerebrovascular disorders. 
     Further, it is doubtful whether or not medicinal treatments are effective on the decline in mental function, i.e., the major symptom of dementia. The overall improvement rate of compound A on this symptom is 46% which is higher than those of pracebo (25%) and other nootropic agent (about 35%). 
     On the other hand, it has been confirmed that compound A is highly safe (OSR=97.9%) and only fugitive side effects were observed in 4 cases (3%). 
     These results indicate that compound A is highly superior in the effects of improving cerebrovascular dementia to drugs conventionally employed therefor. 
     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.