Abstract:
The present invention concerns novel therapeutic compounds having the formula: ##STR1## wherein R is a basic compound comprising 2-amino-4-methylpyridine or 2-amino-2-thiazoline, and methods of making this compound.

Description:
This is a division of application Ser. No. 448,748 filed Mar. 6, 1974, now U.S. Pat. No. 3,994,910. 
    
    
     BACKGROUND OF THE INVENTION 
     Since its discovery almost a quarter of a century ago, phenylbutazone (4-n-butyl-1,2-diphenyl-3,5-pyrazolidinedione) has dominated the field of non-steroid anti-inflammatory drugs despite the fact that it has several serious toxic effects of which ulcerogenesis and fluid retention are probably the most frequent. 
     The most probable reason for the continued success of phenylbutazone is that none of the numerous modifications of its structure nor the even more numerous attempts to design novel structures with anti-inflammatory activity have resulted in a truly successful separation of desired pharmacological activity and undesired toxicity. 
     SUMMARY OF THE INVENTION 
     This invention relates to a process for preparing derivatives of 1,2-diphenyl-3,5-dioxo-4-n-butyl-pyrazolidine having the formula: ##STR2## in which R is represented by a basic compound namely: either 2-amino-4-methyl-pyridine or 2-amino-2-thiazoline, having the respective formulae: ##STR3## 
     It has been found that the compounds of Formula I are a clear improvement over phenylbutazone in that they have increased therapeutic activities but reduced or decreased toxicity. 
     As will be more fully discussed hereinafter, the therapeutic compounds of the present invention have a number of additional advantages over phenylbutazone. For example, smaller doses of the new therapeutic compounds as compared with phenylbutazone can be used with comparable and superior effectiveness. The therapeutic compounds of the present invention have fewer and less severe side effects. 
     In equimolar reaction with 1,2-diphenyl-3,5-dioxo-4-n-butyl-pyrazolidine, these compounds form stable crystalline combinations with an interesting therapeutic action as antiinflammatories, analgesics and analeptics. 
     Pharmacological testing of these compounds led to results to be described hereinafter and reflected in the compound formed by the equimolar combination of 1,2-diphenyl-3,5-dioxo-4-n-butyl-pyrazolidine-2-amino-2-thiazoline, referred to hereinafter as LAS-11871. The equimolar combination of phenylbutazone salt with 2-amino-4-methylpyridine is hereinafter referred to as LAS 6671. 
     The doses of compounds referred to are in mg of salt and not in mg equivalents of phenylbutazone content (i.e., the comparison has been made on a weight for weight basis and not equimolar) since it was considered that this would be more demonstrative of the potential value of the compound. Equimolar comparisons can be made by taking into account the respective molecular weights of LAS 11871 (410.54) and phenylbutazone (308.4) from which it is evident that 100 mg. of LAS 11871 contains the equivalent of 75 mg of phenylbutazone. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The properties and advantages of the therapeutic compounds of the present invention will be discussed below as to some of their therapeutic activities, their toxicity effects and their chemical functions and synthesis. 
     PHARMACOLOGY 
     LAS 11871 and 6671 were compared in a preliminary screening test with phenylbutazone and a commercially available piperazine salt of phenylbutazone and they had definite advantages over each of these two products (see Table I below). 
     TABLE I 
     This shows the effects of LAS- 11871 in various screening tests as compared with phenylbutazone and a piperazine salt thereof. 
     
         ______________________________________      Desired Effects                    Toxic EffectsCompound     CE      AA      AP    UG    TX______________________________________LAS 11871    ++      +++     +++   ++    +LAS 6671     ++      +       ++    ++    +Phenylbutazone        ++      ++      ++    ++    ++Piperazine saltof Phenylbutazone        +       +       +     +     +______________________________________ CE = Inhibition of carrageenin-induced oedema in rat&#39;s paw. AA = Inhibition of contortions induced by acetic acid in mice. AP = Inhibition of yeast-induced pyrexia in rats. UG = Intensity of ulceration produced in the rat stomach. TX = Acute toxicity in mice. 
    
     More detailed studies confirmed these preliminary results and clearly showed that LAS 11871, although more active as an analgesic and anti-inflammatory agent than phenylbutazone, produces fewer gastric lesions and is less toxic than phenylbutazone (see Tables 2, 3, 4, 5 and 6 below). 
     TABLE 2 
     This shows the effect of various doses of phenylbutazone and LAS 11871 on carrageenin-induced oedema in the rat&#39;s paw. 
     
         ______________________________________Compound per os     Volume of paw % Inhibition1 h before  No. of  (ml) standard ± standardcarrageenin animals error         error______________________________________Control     46      0.9663 ± 0.0564                              0.00 ± 5.80Phenylbutazone 200       12      0.2458 ± 0.0454**                             74.60 ± 4.70100         18      0.3139 ± 0.0224**                             67.50 ± 2.30 50         22      0.6886 ± 0.0699*                             28.70 ± 7.24 25         22      0.6545 ± 0.0545**LAS 11871 200       11      0.1545 ± 0.0384**                             84.00 ± 3.97100         18      0.2667 ± 0.0428**                             72.40 ± 4.43 50         22      0.6182 ± 0.0683*                             36.01 ± 7.06 25         22      0.7864 ± 0.0632                             18.60 ± 6.54______________________________________ 
    
     Volume of paws measured 3 hours after injection of carrageenin *P &lt;0.05, &gt;0.001; **P &lt;0.001 for the differences from the control using Student&#39;s &#34;t&#34; test. 
     
                                           TABLE 3__________________________________________________________________________Effects of various doses of phenyl butazone and LAS 11871on granuloma induced in rats by implantation of cotton balls.__________________________________________________________________________                                Percentage        No. of         Dry granuloma ±                                inhibitionmg/Kg/day of compound        granulomas              Weight of wet                      standard error                                Wet    Dryper os       (animals)              granuloma                         (mg)   granuloma                                       granuloma__________________________________________________________________________Control      40 (20)              454.20 ± 11.74                       77.34 ± 0.33                                 0.00 ± 2.60                                        0.00 ± 0.40Phenylbutazone 200        20 (10)              353.40 ± 13.14**                       49.96 ± 4.25**                                22.20 ± 2.80                                       35.40 ± 5.50100          20 (10)              424.50 ± 13.47                       71.23 ± 5.18                                 6.50 ± 2.90                                        7.90 ± 6.70 50          20 (10)              434.75 ± 18.36                       83.94 ± 8.22                                 4.30 ± 4.10                                        8.50 ± 10.6LAS 11871 200        20 (10)              361.21 ± 12.84**                       48.29 ± 1.98**                                20.50 ± 2.80                                       37.60 ± 2.50100          20 (10)              369.69 ± 16.68**                       61.95 ± 4.74*                                18.60 ± 3.70                                       19.90 ± 6.10 50          20 (10)              388.59 ±  8.74**                       61.82 ± 3.16**                                14.40 ± 1.90                                       20.00 ± 4.10__________________________________________________________________________ The figures refer to the net weight of granuloma tissue obtained by subtracting the original weight of the cotton ball. *P &lt;0.05, &gt;0.001 **P &lt;0.001 for the differences from the control using Student&#39;s &#34;t&#34; test. 
    
     
                       TABLE 4______________________________________Effect of various doses of phenylbutazone and LAS 11871on cortortions induced by acetic acidinjected into the abdominal cavity of the mouse______________________________________mg/kg of compound    No. ofper os 1 h before       No. of   contortions ±                            % inhibition ±acetic acid injection       animals  standard error                            standard error______________________________________Control     20       81.65 ± 5.73                             0.00 ± 7.02Phenylbutazone 300       10       42.30 ± 6.75**                            48.20 ± 8.27100         10       47.30 ± 6.70*                            42.10 ± 8.20 30         10       59.00 ± 6.51*                            27.70 ± 7.97LAS 11871 300       10       24.10 ± 3.74**                            70.50 ± 4.60100         10       36.90 ± 6.34**                            54.90 ± 7.76 30         10       44.20 ± 6.03**                            45.90 ± 7.39______________________________________ *P &lt;0.05, &gt;0.001 **P &gt;0.001 for the differences from the control using Student&#39;s &#34;t&#34; test. 
    
     TABLE 5 
     Ulcerogenic activity of LAS 11871 on the stomach as compared with phenylbutazone 
     
                       TABLE 5______________________________________Ulcerogenic activity of LAS 11871 on the stomach as comparedwith phenylbutazone______________________________________mg/kg of compound          No. of    ± standard error ofper os         animals   ulcerogenic indices______________________________________Control        40        0.17 ± 0.07Phenylbutazone 2×200          29        5.00 ± 0.562×100    30        4.33 ± 0.472× 50    30        0.73 ± 0.21LAS 2×200          29        3.65 ± 0.56*2×100    30        2.43 ± 0.41**2× 50    29        0.59 ± 0.19______________________________________ *P &lt;0.1, &gt;0.01 **P &lt;0.01 for the differences between equivalent doses of phenylbutazone and LAS 11871 using Student&#39;s &#34;t&#34; test. 
    
     From Table 2 it is demonstrated that LAS 11871 is at least as active as phenylbutazone against inflammation and at doses of 50 mg/kg and above LAS 11871 was the more active compound. 
     Table 3 compares the activity of LAS 11871 and phenylbutazone against chronic inflammation. It is seen that although both products produced about the same degree of inhibition of granuloma tissue formation at high doses (200 mg/kg), at the lower dose levels (100 and 50 mg/kg) LAS 11871 continued to inhibit the granuloma tissue formation but phenylbutazone did not. 
     Table 4 demonstrates that LAS 11871 is more potent than phenylbutazone as an analgesic. 
     Although LAS 11871, in common with virtually all of the other non-steroid anti-inflammatory compounds, possesses a certain capacity to cause ulcerous lesions in the gastro-intestinal tract. However, as Table 5 illustrates, it is much less active in this respect than phenylbutazone. 
     
         ______________________________________TOXICITYLD50 per os in the rat of LAS 11871Group Dose       No. animals                       No. deaths                               % mortality______________________________________I     1000 mg/kg 10         1       10II    1210 mg/kg 12         3       25III   1470 mg/kg 10         5       50IV    1780 mg/kg 10         9       90V     2150 mg/kg 10         10      100LD50 = 1425 mg/kg (1250 - 1624)LD50 per os in the rat of phenylbutazoneGroup Dose       No. animals                       No. deaths                               % mortality______________________________________I      464 mg/kg  9         1       11II     562 mg/kg 10         4       40III    681 mg/kg 10         8       80IV     825 mg/kg 10         8       80V     1000 mg/kg 10         9       90VI    1210 mg/kg 10         10      100LD50 = 620 (530 - 725)LD50 per os in the rat of 2-amino-thiazolineGroup Dose       No. animals                       No. deaths                               % mortality______________________________________I     316 mg/kg  10         2       20II    383 mg/kg  10         4       40III   464 mg/kg  10         6       60IV    562 mg/kg  10         7       70V     681 mg/kg  10         9       90VI    825 mg/kg  10         9       90LD50 = 430 mg/kg (358 - 516)______________________________________ 
    
     In general, the new therapeutic compounds can be used to treat the same disorders as phenylbutazone. As the above discussion illustrates, the therapeutic compounds of the present invention are less toxic and less ulcerogenic than phenylbutazone, and they have greater effectiveness in anti-inflammatory, analgesic, and antipyretic activity. These therapeutic compounds have been found effective in treating humans as well as animals. For example, LAS 11871 has been shown effective in the treatment of humans with reumatic diseases and LAS 11871 has been used to successfully treat polyarthritics at doses of 200 mg. two, or three times per day. 
     These new therapeutic compounds also have limited and reduced side effects. As noted earlier, they have no anti-diuretic effect and relatively low ulcerogenic potential. They are also relatively free of serious side effects on the central nervous system. 
     However, the compounds, much more than phenylbutazone, show marked inhibition of spontaneous motor activity. This activity is best described as a tranquilizing or muscle relaxant activity. Also, the compounds appear to have immunosuppressant activity. 
     
         ______________________________________PHARMACEUTICAL FORMULATIONS - LAS 11871 capsules     g______________________________________LAS 11871               0.200Colloidal silica        0.005LAS 11871 tabletsLAS 11871               0.250Hydroxypropyl cellulose 0.016Microcrystalline cellulose                   0.100Carboxymethyl starch    0.012Colloidal silica        0.003Magnesium stearate      0.003LAS 11871 suppositoriesLAS 11871               0.300Stearine composition    1.240LAS 11871 suppositoriesLAS 11871               0.5000Ascorbyl palmitate      0.0025Stearine composition    1.9975Dose: from 200 to 1,500 mg/day______________________________________ 
    
     CHEMISTRY AND SYNTHESIS 
     The reaction process for synthesising the therapeutic compounds of the present invention is carried into effect with the use of organic solvents such as methanol, ethanol, acetone, methyl ethyl acetone and dioxane in conditions which will be described in the following Examples. 
     EXAMPLE 1 
     Equimolar combination of 1,2-diphenyl-3,5-dioxo-4-n-butylpyrazolidine-2-amino-4-methyl-pyridine. 
     30.8 g (0.1 mol) of 1,2-diphenyl-3,5-dioxo-4-butyl-pyrazolidine are introduced with agitation into a 500 cc flask and mixed with 150 ml of acetone until complete dissolution. 10.8 g (0.1 mol) of 2-amino-4-methylpyridine which have previously been dissolved in 100 cc of acetone are then added and the mixture is boiled for 30 minutes. It is filtered cold, and 39 g of a product having a melting point of 121°-2° C are crystallized out. 
     EXAMPLE 2 
     Equimolar combination of 1,2-diphenyl-3,5-dioxo-4-n-butylpyrazolidine-2-amino-2-thiazoline. 
     Working is performed under the same conditions as in Example 1 but using ethyl alcohol as the solvent. 2.04 g (0.02 mol) of 2-amino-2-thiazoline are heated in ethanol with 6.16 g (0.02 mol) of 1,2-diphenyl-3,5-dioxo-4-n-butylpyrazolidine for 30 minutes; after cooling, the crystals which form are collected. The substance has a melting point of 161°-2° C. The yield is 86%. The final product was a white crystalline powder virtually insoluble in ether, sparingly soluble in water and soluble in hot ethanol.