Salt of n-methyl-piperazine and 1,2-diphenyl-3,5-dioxo-4-n-butyl pyrazolidine
De Muylder Apr. 8, 1975 SALT OF N-METHYL-PIPERA&#39; ZINE AND 1,2-DIPHENYL-3,5-D1OXO-4-N-BUTYL PYRAZOLIDINE Jean-Marie De Muylder, Kraainem. Belgium Assignee: Societe dEtudes et de Realisations Scientifiques en abrege S.E.R.E.S.C.I. S.p.r.l., Brussels, Belgium Filed: Feb. 21, 1973 Appl. N0.: 334.212  
 inventor:  
 US. Cl. 260/268 R: 424/250 Int. Cl C07d 51/70 Field of Search 260/268 HET. 311. 310.  
 References Cited UNITED STATES PATENTS Rumpf et al. 260/311 OTHER PUBLICATIONS J. LaBarre. et al.. Arch. Intern. Pharmacodyn Therapie 160(2). 265-283 (1966).  
 .I. LaBarre et all, Chemical Abstracts Vol. 65. p. 12440 (1966),  
 Primary E.\&#39;umin erDonald G. Daus Assistant E.\&#39;uminer-.lose Tovar Attorney. Agent. or FirmYoung &amp; Thompson [57] ABSTRACT The new derivative is the equimolecular salt of N-methylpiperazine and l.2-diphenyl-3.5-di0xo-4-nbutyl-pyrazolidine.  
 This new derivative may be used for the treatment of rheumatic diseases. gout and other inflammatory diseases.  
 It is prepared by mixing separately prepared solutions of V N-methylpiperazine and l.2-diphenyl-3.5-dioxo-4-n-butyl-pyrazolidine in the same solvent. in which the desired derivative is insoluble.  
 1 Claim, No Drawings BACKGROUND ()1 THE lNVliN&#39;llON It is known that l.Z-diphenyl-F.5-dioxo-4-n-lnltylpyrazolidine also called phcnylbutazonc&#34; is a pharmaceutical product which has valuable properties for the treatment of rheumatic diseases.  
  A derivative of said phenyllmtazone having unexpected advantages. when compared to phcnylbutalone has now been discovered.  
 SUMMARY OF THE lNVliN&#39;l&#39;lON This invention relates to a new derivative of a substituted pyramlidine. to the use ofthis new derivative and to the preparation thereof.  
  The new derivative of a substituted pyrazolidine is the equimolecular salt of N-methylpiperalinc and L2- diphcn vl-3.5-dioxo-4-n-butyl-pyrazolidine of the following formula.  
  This new salt is a pharmaceutical product having antiinflammatory and analgesic properties which enable the use thereof for the treatment of diseases such as rheumatic diseases, gout and other inflammatory discases.  
  This invention relates therefore also to pharmaceutical compositions. preferably in the form of capsules, tablets and suppositories. containing the new N-methylpiperazine salt as active ingredient together with usual pharmaceutical carriers or excipients.  
  This invention also relates to a method for preparing the new salt of N-methylpiperazine and LZ-diphenyl- 3.5-dioxo-4-n-butyl-pyrazolidine.  
  According to this invention, N-methylpiperazine and diphenyl-l.2-butyl-4-dioxo-3.S-pyrazolidine are both separately dissolved in the same organic solvent selected among the ketones. ethers. esters and chlorinated aliphatic hydrocarbons of the general formula:  
 in which .r 1.2 or 3. =0 to 6 inclusive and z l to 6 inclusive, the obtained Solutions are mixed together and stirred at room temperature until a precipitate of the desired salt isobtained. said precipitate being finally separated by filtration and dried.  
 DETAILED DESCRIPTION OF THE INVENTION The new salt according to this invention shows unexpected and substantial advantages, if compared to 1.2- diphenyl-3.5-dioxo-4-n-butyl-pyrazolidine or phenylbutazone. Tests in vivo on animals and human beings have shown that the salt of the formula (1) is substantially less toxic than phenyllwtazone. whereas the tolerance of said salt is substantially better. Moreover. while the administration of phenyllmtazone to human beings causes a substantial decrease of the excretion of electrolytcs. it has been found that said excretion is normal when the salt of formula (I) is administered. Accordingly. the salt may be administered during a longer period and at higher doses, without the necessity of imposing a salt free or salt poor diet to the patient.  
  It has also been found that the new salt of formula (I) acts much more quickly than the phenylbutazone administered alone.  
 CH (I) plasma proteins, whereas only 30 to 50% of the phenylbutazone contained in the known unsubstituted piperazine salt of phenylbutazone are bound to the blood plasma proteins of human beings having absorbed said known salt.  
  Another advantage of the new N-methylpiperazine salt according to this invention compared to said known piperazine salt is due to the presence of the N- methyl substituent in the piperazine. In view of the presence of said methyl substituent. it is only possible to obtain when N-methylpiperazine is reacted with phenylbutazone an equimolecular salt. whereas the reaction of N-unsubstituted piperazine with phenylbutazone causes frequently the production of a substantial amont of a double salt containing two molecules of phenylbutazone and one molecule of piperazine, such a double salt being undesirable. since it is pharmacologically inactive.  
  Among the solvents which may be used in the process for preparing the new N-methylpiperazine salt according to this invention, the following ones are preferred: acetone, dioxane. tetrahydrofuran. cthylacetate. chlorotorm (CHCI carbon tetrachloride (CCh). dichloromethane (CHgClg). dichloro-l l-ethane (CH CHCI and dichloro-l .2-ethane (CH- Cl-CH- Cl).  
  The precipitate of the desired salt may be washed. for example with hexane or light petroleum ether and dried at room temperature or at about 50C.  
  The solvent used for the preparation of a certain amount of the desired salt may be recovered by filtration of the precipitate of said salt and&#39;used again for dissolving a new fraction of N-methylpiperazine and a new fraction of the pyrazolidine derivative, so as to enable the preparation of a further amount of said salt.  
 EXAMPLES The following examples I to 3 illustrate the method according to this invention, whereas examples 4 to 6 illustrate pharmaceutical compositions according to this invention.  
 EXAMPLE 1 A solution of phenylbutazone or l.2-diphenyl-3.5- dioxo-4-n-butyl-pyrazolidine (3.084 g 0.0] mole) in dioxane 15 ml) is added to a solution of N-methylpiperazine (1.002g 0.01 mole) in dioxane (15 ml). The solutions are stirred at room temperature.  
 The precipitate is collected (3.6 g) and dried.  
 Melting point l388 l39.2C  
 Phenylbutazone 75.6% (calc.: 75.54%)  
 N-methylpiperazine 24.39% (calc.: 24.4671) EXAMPLE 2 To a solution of 20.04 grams (0.2 mole) ofN-methylpiperazine in 300 milliliters ofdichloro-l .Z-ethane. a  
 . solution of 61.6 grams (0.2 mole) of diphenyl-l.2-  
 butyl-4-dioxo-3.5-pyrazolidine in 600 milliliters of dichloro-l .Z-ethane is added.  
  After stirring at room temperature during about two hours. thc&#39;crystals are separated by filtration. washed with hexane and dried at room temperature. 76.9 grams of the desired salt are obtained (Yield 9571).  
 EXAMPLE 3 A solution of diphenyl-l.2-hutyl-4-dioxo-35- pyrazolidine (308 g) in acetone (300 ml) is added to a solution of N-methylpiperazine (100 g) in acetone (500 ml). The mixture is stirred for 2 hours.  
  The crystals are collected on a filter, washed with 250 ml of acetone and dried at room temperature. 383g of pure desired salt area obtained. (Yield 94%).  
 What 1 claim is:  
  1. Equimolecular salt of N-methylpiperazine and 1.2- dipheriyl-B.5-dioxo-4-n-butyl-pyrazolidine.