Abstract:
A pharmaceutical composition is used to treat and prevent a diabetes-dependent type of autoimmune diseases, said pharmaceutical composition comprising a therapeutically effective amount of 3-oxygermylpropionic acid represented by the following formula: 
     
       [(O.sub.1/2).sub.3 GeCH.sub.2 CH.sub.2 CO.sub.2 H].sub.n 
     
     wherein n stands for an integer of 1 or more, optionally with an activating carrier.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a pharmaceutical composition for treating and preventing diabetes-dependent type of autoimmune diseases, which contains as an active ingredient a compound represented by the following formula: 
     
         [(O.sub.1/2).sub.3 GeCH.sub.2 CH.sub.2 CO.sub.2 H].sub.n   (I) 
    
     wherein n stands for an integer of 1 or more, optionally in combination with an activation carrier. 
     The compound used in this invention is in the form of a white acicular crystal having such physicochemical properties as expressed in terms of a specific gravity or density of 2.23, a solubility in water of 1.57 at 20 and a melting or decomposition point of about 230. 
     2. Prior Art 
     Having sophisticated polymerizability and a variety of applications, the compound represented by Formula I or 3-oxygermylpropionic acid has recently attracted public attention in view of its pharmacological activity. This compound, according to some suggestion, has the potentiality of being usable as therapeutic drugs for hepatophathy. However, a serious problem with 3-oxygermylpropionic acid is that it is so unstable in the presence of water that its pharmacological activity decreases drastically (see Japanese Patent Publication No. Sho 57-53800 and U.S. Pat. No. 4,309,412). 
     As a result of having made strenuous investigations to maintain the inherent pharmacological activity of 3-oxygermylpropionic acid in a stable manner, the inventors have already found out that a variety of specific substances can be effectively used as s tabilizers therefor (see Japanese Patent Kokai Publication No. Sho 61-65819) and saccharides can enhance the activity thereof (see Japanese Patent Kokai Publication No. Sho 60-190714). The inventors have also discovered that 3-oxygermylpropionic acid has immunity-accommodative actions (see Japanese Patent Kokai Publication No. Sho 61-161123). 
     Patients with deblitated blood sugar-accommotative functions, esp. those with diabetes are likely to have toxic symptoms due to their antidotal hypometabolism or immunodeficiency and so suffer disorder such as allergy, anaphylaxis, cataract, cutaneous ulcers and acute insufficiency or, reportedly, die in the worst case. Such disorders by and large are considered due to autoimmune diseases. 
     SUMMARY OF THE INVENTION 
     Study after study has turned out that 3-oxygermylpropionic acid, which is of great safety and has such physicochemical properties as expressed in terms of a specific gravity or density of 2.23, a solubility in water of 1.57 at 20 and a melting or decomposition point of about 230, is efficacious against a diabetes-dependent type of autoimmune diseases. 
     More specifically, the present invention provides a pharmaceutical composition greatly efficacious against various diabetic diseases, esp. autoimmune diseases, which contains as an active ingredient 3-oxygermylpropionic acid represented by Formula I: 
     
         [(O.sub.1/2).sub.3 GeCH.sub.2 CH.sub.2 CO.sub.2 H].sub.n   (I) 
    
     wherein n stands for an integer of 1 or more, optionally in combination with an activating carrier. Preferably, the activating carrier is hydroxypropylcellulose, which is used in an amount of 0.005 to 50% by weight per 0.005 to 5% by weight of the active ingredient. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIGS. 1(a) and 1(b) are graphs showing the concentration of glucose in the blood and the amount of insulin in the pancreas measured with a mouse in accordance with Test Example 1, 
     FIGS. 2(a) and 2(b) are graphs showing the concentration of glucose in the blood and the amount of insulin in the pancreas measured with a mouse in accordance with Test Example 2, and 
     FIGS. 3(a) and 3(b) are graphs showing the concentration of glucose in the blood and the amount of insulin in the pancreas measured with a mouse in accordance with Test Example 3. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As so far described, 3-oxygermylpropionic acid is of polymerizability so sophisticated that it can become very unstable in the presence of moisture, thus resulting in a sharp drop of its pharmacological activity. For that reason, it is desired to add a preparatory carrier or a pharmacologically activating carrier to the composition according to this invention and thereby stabilize it. 
     Composition containing 3-oxygermylpropionic acid alone, for instance, are usually provided in the form of orally administered tablets or capsules which are absorbed through digestive tracts. 
     It is noted that although varying dependent upon the type of compound, the type of composition, the age of patient, etc., the composition according to this invention may generally be administered to humans at a dose between 10 mg/kg and 1500 mg/kg. A preferable daily dose to adult patients (weighing 50 kg) is about 150 mg. 
     EXAMPLES 
     The present invention will now be explained more illustratively but not exclusively with reference to the following examples. 
     PREPARATIVE EXAMPLE 1 
     Preparation of the Primary Composition 
     Hydroxypropylcellulose and 3-oxygermylpropionic acid represented by Formula I were mixed together at 2:1. The mixture was kneaded with ethanol serving as a wetting agent and then dried at a temperature lower than 50° C. to obtain a powdery or granular composition. 
     PREPARATIVE EXAMPLE 2 
     Tablet 
     The primary composition was blended with an vehicle, etc. according to the following formulation, and tableted in conventional manners to obtain tablets. 
     
         ______________________________________Ingredients       Amount (mg)______________________________________Primary composition             100Lactose           suitableCarboxymethylcellulose (Ca)             7Crystalline cellulose             40Magnesium stearate             7             200 mg per tablet______________________________________ 
    
     PREPARATION EXAMPLE 3 
     Capsule 
     The primary composition was blended with a vehicle according to the following formulation, and encapsulated in conventional manners. 
     
         ______________________________________Ingredients       Amount (mg)______________________________________Primary composition            100Lactose          40Corn starch      38Magnesium stearate             2______________________________________ 
    
     Toxicity Tests 
     Acute and subacute (chronic) toxicity tests were performed using SD rats and mice which has received 3-oxygermylpropionic acid represented by Formula I (hereinafter referred to Compound a) and the above-mentioned primary composition (hereinafter called Composition b). The results are reported below. 
     For experimentation, a group of 8-10 animals were used. 
     (1) Acute Test 
     
         ______________________________________LD 50 (mg/kg)        Oral administration (no significant        difference between Compound  -a and        Composition  -bMice,male         5,600 or morefemale       5,800 or moreRats,male         7,700 or morefemale       7,050 or more______________________________________ 
    
     Between Compound a and Composition b there was no significant difference in acute toxicity, but the group which received Compound a alone showed general symptoms of appeasement, diarrhea, vomiting and typhlectasis. The group which received Composition b, on the other hand, did not substantially have any particular symptom. 
     (2) Subacute Test 
     Over 3 months, Compound a and Composition b were orally administered to two groups of SD male rats at doses of 256, 380, 640, 1300, 1600 and 4000 mg/kg/day to determined which dose to have no toxic influence at all and which dose to induce positive poisoning. 
     Compound a had no toxic influence whatsoever at 256 mg/kg but induced positive poisoning at 1600 mg/kg. Some animals were sacrificed at 4000 mg/kg. Toxic symptoms then disappeared by no drug treatments over 5 weeks. 
     Composition b had no toxic influence whatsoever at 380 mg/kg but induced positive poisoning at 1300 mg/kg. No animals were sacrificed. 
     Pharmaceutical Tests 
     Continuous 5-day administration of streptozocin (STZ) to an AKR/J1 line mice, that ia an inbred mice with a spontaneous symptom of leukemia, can cause it to take a disease similar to human Type I diabetes (dependent upon insulin). Tests were performed for the purpose of going into influence Compound a and Composition b have on such a mice with streptozosin-induced diabetes. 
     TEST EXAMPLE 1 
     (a) Procedures 
     Streptozocin (STZ) was continuously administrated to the abdominal cavity of a (masculine) mouse belonging to AKR/J1 at a dose of 40 mg/kg for 5 days to induce an increase in the concentration of glucose in the blood and a decrease in the amount of insulin in the pancreas. 
     With Compound a dissolved in a phosphate buffer solution with pH 7.4, the concentration of glucose in the blood was measured at 7 days, 14 days and 21 days from STZ dosing, using a GOD-PAP kit (made by Boehringer Mannheim) based on the glucose oxidase process for measurement. In addition, the amount of insulin in the pancreas, extracted by the acid-ethanol process, was assayed with a radio immuno assay kit (made by Pharmacia Aktiebolag) based on an immunoassay process making use of a competitive reaction by  125  I-labeled insulin (see Soeldner, JS &amp; Slone, D, &#34;Diabetes&#34;, Vol. 14, pp. 771-779, 1985). 
     (b) Results 
     The concentration of glucose in the blood and the amount of insulin in the pancreas, as measured, are shown in the graphs depicted in FIGS. 1(a) and 1(b). The graphs indicate that at 21 days from dosing, Compound a could give rise to significant improvements in the concentration of glucose in the blood increased and the amount of insulin in the pancreas decreased by the administration of STZ at a rejection rate of 5%. 
     TEST EXAMPLE 2 
     (a) Procedures 
     A similar mouse was caused to develop STZ-induced diabetes in a similar manner as referred to in Test Example 1. 
     A solution of Compound a in a phosphate buffer with pH 7.4 was continuously administered to the abdominal cavity of the animal at 5 mg/kg over 7 days from STZ dosing. 
     At 7 days, 14 days and 21 days from STZ dosing, the concentration of glucose in the blood and the amount of insulin in the pancreas were measured in similar manners as mentioned in Test Example 1. 
     (b) Results 
     The concentration of glucose in the blood and the amount of insulin in the pancreas, as measured, are shown in the graphs depicted in FIGS. 2(a) and 2(b). The graphs indicate that at 21 days from dosing, Compound a could give rise to significant improvements in the concentration of glucose in the blood increased and the amount of insulin in the pancreas decreased by the administration of STZ at a rejection rate of 5%. 
     TEST EXAMPLE 3 
     (a) Procedures 
     A similar mouse was caused to develop STZ-induced diabetes in a similar manner as referred to in Test Example 1. 
     A solution of Compound a in a phosphate buffer with pH 7.4 was continuously administered to the abdominal cavity of the animal at 5 mg/kg 15 days from the 7th day after STZ dosing. 
     At 7 days, 14 days and 21 days from STZ dosing, the concentration of glucose in the blood and the amount of insulin in the pancreas were measured in similar manners as mentioned in Test Example 1. 
     (b) Results 
     The concentration of glucose in the blood and the amount of insulin in the pancreas, as measured, are shown in the graphs depicted in FIGS. 3(a) and 2(b). The graphs indicate that at 21 days from dosing, Compound a could give rise to significant improvements in the concentration of glucolse in the blood increased and the amount of insulin in the pancreas decreased by the administration of STZ at a rejection rate of 5%. 
     TEST EXAMPLE 4 
     (a) Procedures 
     Similar mice were caused to develop STZ-induced diabetes in a similar manner as described in Test Example 1. 
     A solution of Compound a in a similar phosphate buffer with pH 7.4 as used in Test Example 1 was continuously administrated at a rejection rate of 5% to the abdominal cavities according to similar dosing schemes as applied in Test Examples 1, 2 and 3. 
     At 21 days from STZ dosing, the degree of cellular infiltration in the Langerhans&#39; islands were assayed under an optical microscope. 
     (b) Results 
     The degree of cellular infiltration in the Langerhans&#39; islands, as assayed, are reported in Table 1. The results indicate that at 21 days from its dosing, Compound a successfully decreased the infiltrated cells increased by STZ dosing, ameliorating the conditions. 
     
                       TABLE 1______________________________________Degrees of cellular infiltration in the Langerhans&#39; islands of miceDegrees of pancreatitis, %                     Incidence of0         I        II       III     pancreatitis(0%)      (0-25%)  (25-50%) (50-100%)                               (%) (I-III)______________________________________STZ +  32     40       11     17      68BufferSTZ +  -a  70     25       4      1       30(1-21days)STZ +  -a  70     23       4      3       30(1-7days)STZ +  -a  68     30       1      1       32(1-21days)______________________________________ 
    
     From the results of the pharmaceutical tests, it can be understood that the compositions according to this invention are greatly efficacious against STZ-induced diabetes similar to the human diabetes model. Thus, they can be used as an active ingredient for diabetes-treating drugs.