Synergistic penicillin-cephalosporin compositions and methods
This is a division of U.S. application Ser. No. 464,157, filed Apr. 25, 1974, which is a continuation-in-part of U.S. application Ser. No. 302,423, filed Oct. 31, 1972, now abandoned. 
    
    
     This invention relates to new antibacterial synergistic compositions containing penicillin derivatives or cephalosporin derivatives, methods for the preparation of such compositions and a method for the treatment of infectious diseases. 
     In particular, this invention relates to an antibacterial synergistic composition consisting essentially of a mixture of: 
     (a) a known, clinically useful penicillin or cephalosporin of the formula ##STR3## wherein R is a residue of an organic acid, the residue being selected from the group consisting of ##STR4## wherein X is selected from the group consisting of --H, --NH 2 , --N 3 , --COOH and --SO 3  H, and wherein R 1  is selected from the group consisting of the bivalent radicals ##STR5## wherein R 2  is hydrogen, a pharmaceutically acceptable cation or an in vivo rapidly hydrolyzed pharmaceutically acceptable ester group, and wherein R 3  is selected from the group consisting of ##STR6## and 
     (b) a known, clinically useful penicillin of the formula ##STR7## wherein R 4  is hydrogen, a pharmaceutically acceptable cation or an in vivo rapidly hydrolyzed pharmaceutically acceptable ester group, and wherein R 5  and R 6  are lower alkyl groups containing not more than four carbon atoms, or R 5  and R 6 , when taken together with the adjacent nitrogen atom, represent a ring system of the formula ##STR8## wherein n is 5, 6 or 7. 
     The above described composition contains the compounds of formula I and II in a weight ratio varying from 10:1 to 1:10, preferably varying from 2:1 to 1:2. Optionally, the composition can be incorporated in a pharmaceutically acceptable carrier. 
     It has surprisingly been found that by combining a compound with the general formula I with a compound of the general formula II to form the above described composition, the antibacterial activity of both compounds may be greatly enhanced. 
     A further surprising finding is that bacterial organisms may develop resistance to a combination of compounds of the formula I and II less readily than to either of the compounds alone. 
     In the formula I above the group R is preferably a group of the formula ##STR9## wherein X is --H, --NH 2 , --N 3 , --COOH or --SO 3  H, provided that the compound of the formula I is a penicillin. However, when the compound of the formula I above is a cephalosporin, the group R is preferably a group selected from ##STR10## 
     A great number of penicillins and cephalosporins with the general formula I are known to have strong antibacterial activity and such penicillins and cephalosporins have been extensively used for the treatment of infectious diseases caused by Gram-positive and Gram-negative bacteria. In the composition of the invention the preferred compounds of the formula I are the penicillins: benzyl-penicillin, 6-(D-α-aminophenylacetamido)penicillanic acid, 6-(D-α-azidophenylacetamido)penicillanic acid, α-carboxybenzylpenicillin, α-hydroxysulphonyl-benzylpenicillin, and the cephalosporins which are illustrated by the specific combinations of the groups R and R 3  in the following table, as well as the corresponding esters and salts of these penicillins and cephalosporins. 
     
         ______________________________________                                    
R             R.sub.3         Name                                        
______________________________________                                    
NCCH.sub.2    CH.sub.3 COO    Cephacetrile                                
                              (R.sub.2 = Na)                              
 ##STR11##                                                                
               ##STR12##      Cephazoline (R.sub.2 = Na)                  
 ##STR13##    CH.sub.3 COO    Cephalotine (R.sub.2 = Na)                  
 ##STR14##    H               Cephalexine (R.sub.2 = H)                   
 ##STR15##                                                                
               ##STR16##      Cephaloridine (R.sub.2 = H)                 
 ##STR17##    CH.sub.3 COO    EPC 807/2b (R.sub.2 = K)                    
 ##STR18##    CH.sub.3 COO    EPC 825/1 (R.sub.2 = K)                     
 ##STR19##    CH.sub.3 COO    EPC 820/1b (R.sub.2 = K)                    
 ##STR20##    N.sub.3         EPC 821/4II (R.sub.2 = K)                   
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     In the above table, the designations R, R 2  and R 3  refer to the formula I above. 
     When the composition of the invention is orally administered, the penicillins or cephalosporins of the formula I may also include such known esters thereof which are rapidly hydrolyzed in vivo. Examples of such suitable ester groups i.e. the group R 2  in the formula I above, are acyloxy-alkyl groups, e.g. the acetoxy-methyl, the pivaloyloxy-methyl or the 1&#34;-acetoxy-ethyl group; or alkyloxycarbonyloxy-alkyl groups e.g. the ethoxycarbonyloxymethyl or the 1&#39;-ethoxycarbonyloxyethyl group. 
     The above mentioned suitable ester groups can be described by the formula ##STR21## wherein A is hydrogen or methyl, and B is alkyl or alkoxy. Preferably the group B should not contain more than four carbon atoms. The preferred meaning of the group A and B is methyl and ethoxy, respectively. 
     Penicillin and cephalosporin esters of this type are known e.g. from German Patent Applications Nos. P 21 44 457.5; P 23 12 041.4; P 23 11 328.2; P 23 12 042.5 and P 23 11 346.4. 
     Penicillins of the general formula II also exhibit strong antibacterial activity, particularly against Gram-negative organisms. These until recently unknown penicillins have been described in Dutch Patent Application No. 7,016,435 and in British Pat. No. 1,293,590. 
     Examples of compounds of the formula II are 
     6-[(hexahydro-1H-azepin-1-yl)methyleneamino]-penicillanic acid, 
     6-[(piperidyl-1)methylenamino]-penicillanic acid, 
     6-[(hexahydro-1(2H)-azocinnyl)methyleneamino]-penicillanic acid, and 
     6-[(N-ethyl-N-isopropylamino)methyleneamino]-penicillanic acid. 
     In the composition of the invention the preferred penicillins of the formula II are those wherein the groups R 5  and R 6 , when taken together with the adjacent nitrogen atom, represent a ring system of the formula ##STR22## wherein n is 5, 6 or 7. Preferably n is 6. 
     When the composition of the invention is orally administered also the penicillin of the formula II may be in the form of a known ester thereof, which is rapidly hydrolyzed in vivo. Examples of suitable penicillin esters included in the formula II are those wherein the group R 4  is an acyloxy-alkyl group, e.g. the acetoxy-methyl, the pivaloyloxy-methyl or the 1&#34;-acetoxy-ethyl group; or an alkyloxycarbonyloxy-alkyl group e.g. the ethoxycarbonyloxymethyl or the 1&#39;-ethoxycarbonyloxyethyl group. Also these ester groups can be described by the formula ##STR23## wherein A and B have the meaning given above. Penicillin esters of this type, and included in the formula II, are known e.g. from Dutch Patent Applications Nos. 7,016,435 and 7,303,434. 
     Examples of preferred penicillin esters of the formula II are pivaloyloxymethyl 6-[(hexahydro-1H-azepin-1-yl)methyleneamino]penicillanate, acetoxy-methyl 6-[(hexahydro-1H-azepin-1-yl)methyleneamino]penicillanate, pivaloyloxymethyl 6-[(hexahydro1(2H)-azocinnyl)methyleneamino]penicillanate, ethoxycarbonyloxymethyl 6-[(hexahydro-1H-azepin-1-yl)methyleneamino]penicillanate, 1&#39;-ethoxycarbonyloxy-ethyl 6-[(piperidyl-1.)methyleneamino]-penicillanate, 1&#39;-acetoxyethyl 6-[(hexahydro-1H-azepin-1-yl)-methyleneamino]penicillanate, 1&#39;-ethoxycarbonyloxyethyl 6-[(hexahydro1(2H)azocinnyl)methyleneamino]penicillanate, and 1&#39;-ethoxycarbonyloxy-ethyl 6-[(hexahydro-1H-azepin-1-yl)methyleneamino]-penicillanate, and pharmaceutically acceptable salts thereof. 
     The composition according to the invention can be prepared by various mixing operations well known for the preparation of compositions containing penicillins or cephalosporins. The mixing operations may be accompanied by chemical reactions between the constituents of the new composition. The mixing operations may also be combined with the simultaneous preparation of esters and salts of the penicillins and cephalosporins included in the composition of the invention. It is also to be noted that the new composition according to the invention in some respects can be regarded as one new chemical individual, as the new composition has an antibacterial activity which is unique and widely different from the activity which can be deduced from a calculation based upon the activity of the single constituents. 
     The composition of the present invention may be administered either orally or by injection. The composition may have optionally incorporated therewith other substances, e.g. pharmaceutically acceptable solid or liquid carriers or diluents and may be in any of the conventional pharmaceutical forms known to the art for penicillin therapy, for example compositions suitable for oral administration, for example tablets, granules, capsules, dispersible powders for the preparation of aqueous dispersions for oral use, solutions, suspension or emulsions, or compositions suitable for parenteral administration, for example aqueous or nonaqueous solutions or suspensions, or dispersible powders for the preparation of sterile aqueous dispersions, or compositions suitable for topical administration, for example ointments. 
     The compositions according to the invention show low toxicity and are well tolerated. In the treatment of bacterial infections in man, the composition of the invention is for example administered in amounts corresponding to 5 to 200 mg/kg/day, of the active ingredients of the composition, preferably in the range of 10 to 100 mg/kg/day in divided dosages, e.g. two, three or four times a day. They are e.g. administered in dosage units containing e.g. 175, 350, 500 and 1000 mg of the active ingredients of the composition. 
    
    
     The following examples illustrate the remarkable antibacterial synergistical effect of the compositions according to the invention. 
     EXAMPLE 1 
     In vitro-effect of the combination of 6-(D-α-aminophenylacetamido)penicillanic acid and 6[(hexahydro-1H-azepin-1-yl)methyleneamino]penicillanic acid 
     The in vitro activity of 6-(D-α-aminophenylacetamido)penicillanic acid (I), 6-[(hexahydro-1H-azepin-1-yl)methylene amino]penicillanic acid (II) and of a combination (III) of equal parts of the two compounds against clinically isolated enterobacteria was determined in a serial dilution test. Tryptose phosphate broth, containing the appropriate concentrations of the compounds or of the combination of them, was inoculated with 0.5×10 4  -5×10 4  organisms of the various microorganisms tested and incubated overnight at 37° C. Minimum inhibitory concentrations (M.I.C.) were taken as the concentrations of the compounds or of the combination at which no visible growth occurred. 
     
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               M.I.C. (μg/ml)                                          
Microorganism                                                             
           Strain No.                                                     
                     I         II      III                                
______________________________________                                    
Coliform   3/70      1.56      12.5    0.78                               
Coliform   9/70      3.12      3.12    0.39                               
Coliform   10/70     3.12      3.12    0.78                               
Coliform   17/70     3.12      0.78    0.39                               
Proteus mirabilis                                                         
           35895     25        0.78    0.39                               
Proteus vulgaris A   0.78      0.19    0.08                               
Proteus vulgaris B   50        1.56    0.78                               
Proteus    12/70     100       3.12    0.78                               
Proteus    13/70     100       3.12    0.78                               
Protues    20/70     &gt;100      &gt;100    25                                 
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     EXAMPLE 2 
     In vitro-effect of combinations of 6-[(hexahydro-1H-azepin-1-yl)-methyleneamino]penicillanic acid with various penicillins 
     Using the same technique as described in Example 1 the in vitro-activity of 6-[(hexahydro-1H-azepin-1-yl)methyleneamino]penicillanic acid (II), of various penicillins and of 1:1-combinations of II with the respective penicillin was determined against a clinically isolated coliform bacterium (No. 9/70). 
     
         ______________________________________                                    
              M.I.C. (μg/ml)                                           
Penicillin      I       II      1:1 combination                           
______________________________________                                    
benzylpenicillin                                                          
                25      3.12    0.78                                      
6-(D-α-azidophenylacet-                                             
amido)penicillanic acid                                                   
                50      3.12    1.56                                      
α-carboxybenzylpenicillin                                           
                12.5    3.12    0.38                                      
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     EXAMPLE 3 
     In vivo-activity of the combination of 6-(D-α-aminophenylacetamido)penicillanic acid and 6-[(hexahydro-1H-azepin-1-yl)methyleneamino]penicillanic acid 
     Groups of 10 animals of female NMRI white mice, 17-19 g, were given intraperitoneally inocula of the test bacterium E.coli III and immediately afterwards treated subcutaneously with the appropriate diluted aqueous solutions of 6-(D-α-aminophenylacetamido)penicillanic acid (I), 6-[(hexahydro-1H-azepin-1-yl)methyleneamino]penicillanic acid (II) and of a 1:1 combination (III) of the two compounds. The number of deaths in the various groups were recorded after 96 hours and the mean curative doses (CD 50 ) were calculated. (In the table, LD 50  gives the dilution of an overnight culture of the organism causing a 50% death rate in animals receiving no therapy; the number of LD 50  -doses records the severity of the infections given to the animals.) 
     
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                 CD.sub.50 (mg/kg)                                        
LD.sub.50                                                                 
         LD.sub.50 -doses given                                           
                       I       II       III                               
______________________________________                                    
1.5 · 10.sup.-3                                                  
         6.6            5.5    2.0       1.0                              
8.1 · 10.sup.-4                                                  
         1.2 · 10.sup.4                                          
                       250     &gt;500     210                               
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     EXAMPLE 4 
     In vitro-effect of the combination of 6-(D-α-aminophenylacetamido)penicillanic acid and 6[(piperidyl-1)methyleneamino]penicillanic acid 
     Using the technique described in example 1, the in vitro activity of 6-(D-α-aminophenylacetamido)penicillanic acid (I), 6-[(piperidyl-1)-methyleneamino]penicillanic acid (IV) and of a combination (V) of equal parts of the two compounds against clinically isolated enterobacteria was determined in serial dilution tests. 
     
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               M.I.C. (μg/ml)                                          
Microorganism                                                             
           Strain No.                                                     
                     I         IV      V                                  
______________________________________                                    
Coliform   3/70      3.12      3.12    0.78                               
           7/70      3.12      1.56    0.78                               
           8/70      3.12      6.25    0.78                               
           14/70     6.25      3.12    1.56                               
           16/70     3.12      1.56    0.78                               
           17/70     6.25      1.56    0.78                               
Proteus    4/70      1.56      25      0.78                               
           6/70      0.39      3.12    0.18                               
           7/70      1.56      50      0.78                               
           9/70      6.25      100     1.56                               
           10/70     1.56      25      0.78                               
Klebsiella-                                                               
Enterobacter.                                                             
           1/70      50        &gt;100    3.12                               
           2/70      25        12.5    3.12                               
           5/70      100       &gt;100    12.5                               
           7/70      &gt;100      &gt;100    100                                
           9/70      50        3.12    1.56                               
           10/70     50        &gt;100    25                                 
           431       100       &gt;100    12.5                               
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     EXAMPLE 5 
     In vitro-effect of combination of 6[(piperidyl-1)-methyleneamino]penicillanic acid (IV) with various penicillins 
     Using the same technique as described in Example 1 the in vitro activity of 6[(piperidyl-1)-methyleneamino]-penicillianic acid (IV), of various penicillins, and of 1:1 combinations of IV with these penicillins, was determined against a clinically isolated coliform bacterium. 
     
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              M.I.C. (μg/ml)                                           
Penicillin      --      IV      1:1 combination                           
______________________________________                                    
Benzylpenicillin                                                          
                25      6.25    1.56                                      
6-(D-α-azidophenylacet-                                             
amido)penicillanic acid                                                   
                50      6.25    1.56                                      
α-Carboxybenzylpenicillin                                           
                12.5    6.25    1.56                                      
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     EXAMPLE 6 
     Emergence of resistance for E.coli III against 6-(D-α-amino-phenylacetamido)penicillanic acid, 6-[(piperidyl-1)-methyleneamino]penicillanic acid, and a 1:1 combination of the two compounds 
     Subculturing using a serial twofold broth dilution technique was performed with 6-(D-α-amino-phenylacetamido)-penicillanic acid (I), 6-[(piperidyl-1)methyleneamino]penicillanic acid (IV) and a 1:1 combination of I+IV. As inocula were used bacteria from the tube with the highest concentration of compound still permitting visible growth to the naked eye after incubation at 37° C. overnight. The following increases in MIC-values were noted. 
     
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           MIC (μg/ml)                                                 
Passage      I          IV        I + IV                                  
______________________________________                                    
0            1.56       0.78      0.38                                    
1            6.25       6.25      1.56                                    
2            25         6.28      0.78                                    
3            50         25        0.78                                    
4            50         25        1.56                                    
5            100        25        3.12                                    
6            100        25        3.12                                    
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     EXAMPLE 7 
     Emergence of resistance for a coliform microorganism against 6-(D-α-aminophenylacetamido)penicillanic acid, 6-[(hexahydro-1H-azepin-1-yl)methyleneamino]penicillanic acid and a combination of the two compounds 
     Subculturing using a serial twofold broth dilution technique was performed with 6-(D-α-aminophenylacetamido)-penicillanic acid (I), 6-[(hexahydro-1H-azepin-1-yl)methyleneamino]penicillanic acid (II), and a 1:1 combination of I and II. The strain used was a clinically isolated coliform. As inocula were used bacteria from the tube with the highest concentration of compound still permitting visible growth to the naked eye after incubation at 37° C. overnight. The following increases in MIC values were noted. 
     
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            MIC (μg/ml)                                                
Passage       I         II        I + II                                  
______________________________________                                    
0             1.56      0.39      0.38                                    
1             3.12      6.25      0.78                                    
2             3.12      25        0.38                                    
3             6.25      25        0.78                                    
4             6.25      25        0.78                                    
5             6.25      25        0.78                                    
6             6.25      12.5      1.56                                    
7             12.5      25        1.56                                    
8             12.5      25        1.56                                    
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     EXAMPLE 8 
     In vitro effect of the combination of cephalotin and 6-[(N,N-diethylformamidino)-N&#39;-amino]-penicillanic acid 
     Using the technique described in Example 1 the in vitro activity of cephalotin (VI) and 6-[(N,N-diethylformamidino)-N&#39;-amino]penicillanic acid (VII) and of a combination of equal parts of the compounds against clinically isolated strains of Coliforma and Klebsiella-Enterobacter was determined in serial dilution tests. 
     
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            Strain                                                        
                  MIC (mg/ml)                                             
Microorganism No.     VI     VII     VI + VIII                            
______________________________________                                    
Coliforma     3       6.25   6.25    1.56                                 
              7       12.5   6.25    1.56                                 
              14      12.5   12.5    6.25                                 
              16      6.25   6.25    3.12                                 
Klebsiella-Enterobacter                                                   
              5       25     &gt;100    12.5                                 
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     EXAMPLE 9 
     In vitro effect of combinations of 6-(D-α-aminophenylacetamido)penicillanic acid and 6-[(N,N-diethylformamidino)-N&#39;-amino]penicillanic acid 
     Using the technique described in Example 1 the in vitro effect of combinations of 6-(D-α-aminophenylacetamido)-penicillanic acid (I) and 6-[(N,N-diethylformamidino)-N&#39;-amino]penicillanic acid (VII) in the ratios 1:1, 1:2 and 2:1 against clinically isolated strains of Coliforma, Klebsiella-Enterobacter and Proteus was determined in serial dilution tests. 
     
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           MIC (μg/ml)                                                 
Micro- Strain          I + VII                                            
                            I + VII                                       
                                  I + VII                                 
organism                                                                  
       No. I     VII   1:1  1:2   2:1                                     
__________________________________________________________________________
Coliforma                                                                 
       1   1.56  3.12  1.56 0.39 + 0.78                                   
                                  0.78 + 0.39                             
       4   3.12  3.12  3.12 0.78 + 1.56                                   
                                  l.56 + 0.78                             
       7   1.56  6.25  3.12 0.78 + 1.56                                   
                                  0.78 + 0.39                             
       13  3.12  12.5  3.12 0.78 + 1.56                                   
                                  0.78 + 0.39                             
       16  3.12  6.25  1.56 0.78 + 1.56                                   
                                  0.78 + 0.39                             
Klebsiella-                                                               
Enterobacter                                                              
       1   50    &gt;100  12.5 6.25 + 12.5                                   
                                  12.5 + 6.25                             
       5   100   &gt;100  12.5 6.25 + 12.5                                   
                                  12.5 + 6.25                             
       7   &gt;100  &gt;100  50   25 + 50                                       
                                  100 + 50                                
       8   25    12.5  25   1.56 + 3.12                                   
                                  6.25 + 3.12                             
Proteus                                                                   
       9   3.12  100   3.12 3.12 + 6.25                                   
                                  1.56 + 0.78                             
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     EXAMPLE 10 
     In vitro effect of combinations of 6-[(hexahydro-1H-azepin-1-yl)methyleneamino]penicillanic acid with various cephalosporins 
     Using the same technique as described in Example 1 the in vitro activity of 6-[(hexahydro-1H-azepin-1-yl)methyleneamino]penicillanic acid (II), of various cephalosporins previously mentioned in this specification, and of 1:1 combinations of II with these cephalosporins was determined against a clinically isolated strain of Klebsiella-Enterobacter (strain 4/71) 
     
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        M.I.C. (μg/ml)                                                 
Cephalosporin                                                             
          --          II        1:1 combination                           
______________________________________                                    
Cephacetrile                                                              
          50          &gt;100      50                                        
Cephazoline                                                               
          12.5        &gt;100      6.25                                      
Cephalotine                                                               
          50          &gt;100      6.25                                      
Cephalexine                                                               
          50          &gt;100      6.25                                      
Cephaloridine                                                             
          25          &gt;100      3.12                                      
EPC 807 2/b                                                               
          &gt;100        &gt;100      12.5                                      
EPC 825/1 &gt;100        &gt;100      25                                        
EPC 820/1b                                                                
          &gt;100        &gt;100      25                                        
EPC 821/4II                                                               
          100         &gt;100      6.25                                      
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     EXAMPLE 11 
     In vitro effect of combinations of 6-[(hexahydro-1H-azepin-1-yl)methyleneamino]penicillanic acid with various cephalosporins 
     Using the same technique as described in Example 1 the in vitro activity of 6-[(hexahydro-1H-azepin-1-yl)methyleneamino]penicillanic acid (II), of various cephalosporins and of 1:1 combinations of II with these cephalosporins was determined against a clinically isolated strain of Proteus (Proteus Mirabilis I 190). 
     
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           M.I.C. (μg/ml)                                              
Cephalosporin                                                             
             --      II       1:1 combination                             
______________________________________                                    
Cephacetrile 12.5    &gt;100     3.12                                        
Cephazoline  6.25    &gt;100     0.78                                        
Cephalothine 3.12    &gt;100     0.78                                        
Cephalexine  25       100     1.56                                        
Cephaloridine                                                             
             6.25     100     0.78                                        
EPC 807 2/b  25      &gt;100     3.12                                        
EPC 825/1    25      &gt;100     1.56                                        
EPC 820/1b   50      &gt;100     6.25                                        
EPC 821/4II  12.5    &gt;100     1.56                                        
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