Abstract:
A method of treating diarrhoea and promoting weight gain in mammals by administration of an effective amount of a compound selected from the group consisting of 4-fluoro-γ-(4-alkylpiperidino)-butyrophenone of the formula ##STR1## wherein R is lower alkyl having 1 to 6 carbon atoms, or pharmaceutically acceptable acid addition salts thereof.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to a method for treating diarrhoea in mammals caused by strains of bacteria producing enterotoxins, i.e. E. coli, V. cholerae and C. perfringens, by administering a 4-fluoro-γ-(4-alkylpiperidino)-butyrophenone of the formula ##STR2## wherein R is lower alkyl having 1 to 6 carbon atoms, or pharmaceutically acceptable acid addition salts thereof. 
     The compounds have shown pronounced effect on for example travellers diarrhoea in man and diarrhoea associated with E. coli in pigs. Diarrhoea often is caused by enterotoxins from different bacterial strains that stimulate the adenylate cyclase/cyclic AMP system in the intestinal mucosa (Field, M. Ciba Foundation Symposium 42, Elsvier 1978, Amsterdam). Mucosal adenylate cyclase is also stimulated by diarrhoegenic hormones like vasoactive intestinal peptides and prostaglandins, thus supporting the concept that there exist cyclic AMP regulated transport mechanisms for electrolytes and fluid across the intestinal mucosa. By such mechanisms a prolonged stimulation of adenylate cyclase induces profuse diarrhoea followed by dehydration and sometimes death. 
     The mechanism of the adenylate cyclase system in the intestinate membranes is indeed complex and at present not known in detail. Although cyclic-AMP stimulated secretion appears to be electrogenic for anion it is nevertheless Na +  -dependent. Removal of Na +  (from the bothing medium) abolishes net Cl -  secretion (Powel et al., Am. J. Physiol. 1974, 227, 1436). 
     An inhibitor of the adenylate cyclase system, chlorpromazine (The Merck Index 9th Ed., 2175) has been tested for its effect on diarrhoea caused by E. coli in piglets (Lonnroth et al., Infect. Immun. 1979, 24, 900-905). In addition to a repressing effect of chlorpromazine on diarrhoea certain disadvantages exist such as reduction in blood pressure, pronounced sedation at a dosage required for clinical effect, slow elimination and the risk of inducing contact allergy. Due to the sedation piglets treated with chlorpromazine often will be trampled and crushed by the mothersow. Lonnroth (4th International Symposium on Phenothiazines and Related Drugs, Zurich, Sept. 9-13, 1979) investigated butyrophenones as to their effect on intestinal secretion and reported that they have no or very little effect on intestinal secretion in contrast to sedative phenothiazines. However, through comprehensive research work the inventors have found that melperone (4-fluoro-γ-(4-methyl-piperidino)-butyrophenone) of the formula ##STR3## (compound and process for the preparation thereof known from British Pat. No. 1,142,143), a butyrophenone characterized by few motoric, central and autonomic side effects (Ventulani et al., Pharm. Pharmacol. 1970, 22, 105), has an inhibiting effect on the intestinal adenylate cyclase system evaluated by the gut fluid secretion test (test system described by Lonnroth et al., Infect. Immun. 1979, 24, 900-905). 
     Hitherto a great number of different antibiotics have been used to treat diarrhoea associated with strains of E. coli. In vitro tests and clinical experience have shown a pronounced bacterial resistance against the antibiotics used. Therefore, the principle of treating these diseases through enzyme inhibition, without the risk of resistance, is superior. Furthermore, the effect of an enzyme inhibitor (such as melperone according to the invention) compared to antibiotics may be more rapid since the effect is directed to the target organ and not indirectly via the killing of the causative microorganisms. This suggestion is supported by the results in experiment II below and partly also by the trials with the previously suggested compound chlorpromazine (Lonnroth et al., Infect. Imm. 1979, 24, 900-905). 
     The litter morbidity of diarrhoea in piglets, 0-5 weeks old, is about 15-20% in affected herds and the mortality about 70-100% (1-2 pigs/litter) (Backstrom, Acta Vet. Scand. suppl. 41, 1973; Svendsen et al., Nord. Vet. Med. 1975, 27, 85-101). 
     SUMMARY OF THE INVENTION 
     Thus, our invention relates to a method of treating diarrhoea in mammals caused by strains of bacteria producing enterotoxins, i.e. E. coli, V. cholerae and C. perfringens, by administration of an effective amount, such as 0.1 to 20 mg per kg body weight of a compound selected from the group consisting of 4-fluoro-γ-(4-alkylpiperidino)-butyrophenone of the formula ##STR4## wherein R is lower alkyl having 1 to 6 carbon atoms, or pharmaceutically acceptable acid addition salts thereof. 
     A further advantage obtained with the method of this invention is that litters of piglets increase in weight compared to litters which are left untreated. 
     The preferred compound is 4-fluoro-γ-(4-methyl-piperidino)-butyrophenone which preferably is administered in an amount of 2 to 6 mg per kg body weight to pigs suffering from diarrhoea and in an amount of 0.1 to 2 mg per kg body weight to men suffering from travellers&#39; diarrhoea. 
     The butyrophenone derivatives employed in the method of this invention can be administered orally or parenterally in combination with non-toxic liquid or solid carriers. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The effect of melperone on diarrhoea associated with E. coli infections has been tested in laboratory investigations and clinical trials. 
     The laboratory tests were performed as described by Lonnroth et al., Infect. Immun. 1979, 24, 900-905. The results are shown in Table I. It is evident that melperone inhibits the intestinal fluid secretion indicating an effect on the adenylate cyclase system in intestinal mucosa. In case of melperone this inhibition is a more specific one compared to chlorpromazine and haloperidol (4&#39;-fluoro-4-hydroxy-4-(4-chlorophenyl)piperidinobutyrophenone), which drugs also block dopamine stimulated adenylate cyclase in brain tissue (Table I). In addition to this direct effect of melperone on the intestinal adenylate cyclase system, which is also seen after treatment with chlorpromazine, melperone shows pronounced antianxiety properties which may have some significant role in regulating intestinal electrolyte transport. This may be of importance as we know that stress conditions aggravate the outbreak of profuse diarrhoea. 
     The clinical trials were performed in a farm where outbreaks of profuse watery diarrhoea occurred among piglets. Three different double blind experiments were performed in piglets with an average weight of about 5 kg. 
     EXPERIMENT I 
     Every second litter suffering from diarrhoea was treated with 1.5 mg melperone intramuscular per kg body weight and every second litter with 25.0 mg Tylosin (The Merck Index, 9th Ed., 9486) intramuscular per kg body weight. In this experiment only the time of reversal of diarrhoea and the number of piglets who died were recorded. In each group 40 piglets were treated. 
     The results indicated that diarrhoea ceased more rapidly in the litters treated with melperone compared to Tylosin. Two piglets died in the group treated with Tylosin and none in the group treated with melperone. 
     EXPERIMENT II 
     Every second litter with profuse diarrhoea was treated with 1.5 mg melperone per kg body weight and every second litter with 6.7 mg trimetoprim (The Merck Index, 9th Ed., 9377)+25.0 mg sulfadoxin (The Merck Index, 9th Ed., 8697) (Borgal, Hoechst AG) per kg body weight. Before treatment each piglet within a litter was inspected, eartagged and the weight was recorded. As not all of the piglets in every litter suffered from diarrhoea, five groups of experimental piglets were obtained as follows: 
     (1) Piglets with diarrhoea treated with melperone. 
     (2) Piglets with diarrhoea treated with Borgal. 
     (3) Piglets without diarrhoea treated with melperone. 
     (4) Piglets without diarrhoea treated with Borgal. 
     (5) Piglets without diarrhoea and untreated. 
     Each pig participating in the experiments was inspected the day after treatment for presence of diarrhoea and the weight was recorded 7, 14 and 21 days after treatment. All piglets who died were necrospied. Fecal samples were obtained from every tenth piglet with diarrhoea for bacteriological examination. 
     EXPERIMENT III 
     Treatment with Borgal was compared to melperone (dosage 3.0 mg/kg body weight). The other experimental conditions were the same as in experiment II. The results are summarized in Tables IV and V. 
     The use of melperone compared to Borgal (trimetoprim-sulfadoxin) indicates that diarrhoea stopped in about the same percentage after one treatment. The mortality was low after both treatments and no significant differences between the two drugs were noticed. Melperone has certain advantages compared to antibiotics since no resistance can be awaited. In addition to this the side effects of chlorpromazine used as inhibitor of the adenylate cyclase system do not appear after the use of melperone. 
     EXPERIMENT IV 
     In a litter of twelve piglets suffering from diarrhoea which was left untreated, ten of the piglets died. 
     Piglets treated once and in which no diarrhoea was observed after one day are recorded as group A (Table II). Piglets treated twice one day apart are recorded as group B. Piglets treated three times one day apart are recorded as group C. Untreated piglets are recorded as group D and the untreated controls not suffering from diarrhoea are recorded as group E. The results are summarized in Tables II and III. 
     
                       TABLE I______________________________________           Inhibition of                       Inhibition of           cholera-induced                       DA-stimulated           diarrhoea   cyclic AMPSubstance       IC.sub.50 mg/kg                       IC.sub.50 10.sup.-6 M______________________________________Chlorpromazine  1.5         0.41Haloperidol(4&#39;-fluoro-4-hydroxy-4-(4-chlorophenyl)piperidino)-           &gt;&gt;5.0       0.45butyrophenoneMelperone       2.9         7.10______________________________________ 
    
     Half-maximal inhibition (IC 50  mg/kg) estimated 4 hours after challenge with 10 μg of choleratoxin (to the intestine). The drug was given i.m. 1 hour before the choleratoxin. The drug concentrations causing 50% inhibition of DA-stimulated cyclic AMP (IC 50 , 10 -6  M) in striatal homogenates by 80 uM dopamine (DA). 
     
                       TABLE II______________________________________                    Daily weight gain (g)  Group     Mor-    Group  A   B     C     E   tality                            A    B    C    E______________________________________Borgal   92    30    18      --    209  184  169(diarrhoea)Borgal (no    28                  --    215diarrhoea)Controls (no             35                       210diarrhoea,untreated)______________________________________ 
    
     No. of treated piglets in group A-C and the daily weight gain during three weeks after treatment (Exp. II). 
     
                       TABLE III______________________________________             Mor-   Daily weight gain (g)Group             tal-   GroupA         B     C     D   E   ity  A    B    C    E______________________________________Melperone   83    27    21          --   194  180  160(diarrhoea)Melperone(no diarr-   17                      --   206hoea)Controls                    15  --                  205(no diarr-hoea, un-treated)Controls                12      10(diarrhoea,untreated)______________________________________ 
    
     No. of piglets in group A-E and the daily weight gain during three weeks after treatment. Dosage of melperone was 1.5 mg/kg body weight (Exp. II and IV). 
     
                       TABLE IV______________________________________            Mor-    Daily weight gain (g)  Group     tal-    Group  A   B     C     E   ity   A    B    C    E______________________________________Borgal   47    11    4       2     236  253  222(diarrhoea)Borgal (no    19                  --    259diarrhoea)Controls (no             20                       253diarrhoea,untreated)______________________________________ 
    
     No. of piglets in group A-E and the daily weight gain during three weeks after treatment (Exp. III). 
     
                       TABLE V______________________________________             Mor-   Daily weight gain (g)Group             tal-   GroupA         B     C     D   E   ity  A    B    C    E______________________________________Melperone   48    12    10           4   227  206  233(diarrhoea)Melperone   10                      --   247(no diar-rhoea)Controls                    14  --             251(no diar-rhoea, un-treated)Controls                12      10(diarrhoea,untreated)______________________________________ 
    
     No. of piglets in group A-E and the daily weight gain during three weeks after treatment. Dosage of melperone was 3.0 mg/kg body weight (Ex. III and IV). 
     The compounds of the invention, together with conventional pharmaceutical carriers, can be employed in unit dosage forms such as solids, for example, tablets or capsules or liquid solutions, suspensions or elixirs for oral administration, and injections, or liquid solutions, emulsions and the like for parenteral use. 
     EXAMPLE 1 
     Sterile solution of injection 
     The following pharmaceutical compositions are formulated with the indicated amount of active agent using conventional techniques. 
     
         ______________________________________Ingredients            Weight (mg)______________________________________Metylperone (4-fluoro-γ-(4-methyl-piperidino)-butyrophenone hydrochloride)                  20Sodium chloride        9.3Sodium dihydrogen phosphate                  5.08Disodium edetate (ethylenediaminetetra-acetic acid disodium salt)                  0.2Benzyl alcohol         40Sodium hydroxide       q.s. to adjust pH at                  5.9-6.1Water double-distilled q.s. to 2 ml______________________________________ 
    
     Filtration through Membrane Filter, aseptic filling into ampoule and treatment in autoclave with streaming vapor for twenty minutes. 
     EXAMPLE 2 
     Tablets 
     Tablets suitable for oral administration which contain the following ingredients may be prepared by conventional techniques. 
     
         ______________________________________Ingredients          Weight (mg)______________________________________4-fluoro-γ-(4-methyl-piperidino)-                5butyrophenone hydrochlorideMagnesium stearate   3Cellulose powder     6Talcum               3Lactose              143Aerosil              1______________________________________ 
    
     It is to be understand that the invention is not to be limited to the exact details of operation or exact compounds, compositions, methods, or procedures shown and described, as obvious modifications and equivalents will be apparent to one skilled in the art.