Method for treating renal insufficiency
This application is a continuation in part of our prior filed co-pending application, Ser. No. 516,936 filed July 25, 1983, now abandoned. 
    
    
     The invention relates to a method for preventing or treating renal insufficiency by increasing renal glomerular filtration rate and renal plasma flow in hypertensive patients in need thereof with 8-(3-tert.-butylamino-2 hydroxypropoxy)-thiachroman. 
     The invention comprises the use of a pharmaceutical composition having a renal vasodilatory property and containing as active ingredient 8-(3-tert.-butylamino-2-hydroxypropoxy)-thiachroman, or one of the addition salts thereof with a mineral or organic acid, in combination or in admixture with an inert, pharmaceutically acceptable, non toxic excipient or carrier. 
     The compound used according to the invention has been described in Example 2 of U.S. Pat. Nos. 3,960,891 and 4,032,648 (MALEN et al.), in which it is described as having beta-blocking properties. 
     The renal vasodilatory property is, however, completely separate from the beta-blocking properties previously described in the above-mentioned patents and in the publication of Laubie et al., C.R. Acad. Sci. (1971), 273 (D), 1243, and is not found in the know beta-blockers, such as, for example, alprenolol, propranolol, practolol, nadolol, etc. 
     8-(3-tert.-butylamino-2-hydroxypropoxy)-thiachroman, referred to hereinafter as &#34;THPT&#34;, contains one asymmetric carbon atom in the side chain. It may be resolved to give the laevorotatory and dextrorotatory isomers. 
     The pharmaceutical composition, having the properties according to the invention, contains from 2 to 10 mg of one or the other of the optical isomers of 8-(3-tert.-butylamino-2- hydroxypropoxy)-thiachroman, or one of the addition salts thereof with a mineral or organic acid, in admixture with an inert, pharmaceutically acceptable, non-toxic excipient. 
     As addition salts with a mineral acid there may be mentioned the hydrochloride, the hydrobromide, the phosphate, the hydriodide or the perchlorate; as addition salt with an organic acid there may be mentioned the formate, the acetate, the butyrate, the lactate, the tartrate, the pyruvate, the maleate or fumarate, the benzoate, the nicotinate, etc. 
     The invention is based on the fact that the composition according to the invention has been found to increase the glomerular filtration rate and the renal plasma flow, in contrast to the known beta-blockers, especially propranolol, pindolol or oxprenolol, which considerably decrease these activities (of the order of 30 %), making their use dangerous, or completely impossible, in the treatment of hypertension associated with renal insufficiency. 
     Renal hemodynamic alteration induces a decrease of the sodium (Na + ) excretion. The resultant sodium retention tends to limit the antihypertensive effect of the known beta-blockers. Sodium retention is a well known adverse effect of these drugs. 
     The pharmacological tests and clinical trials carried out with the composition reveal the fact that THPT significantly increases the glomerular filtration rate, the renal plasma flow and the sodium excretion in normotensive dogs. Additionaly, clinical trials establish that the drug significantly increases the glomerular filtration rate and the renal plasma flow in patients suffering from hypertension and does not modify them significantly in normotensive patients with or without renal insufficiency. 
     As a result, the pharmaceutical composition according to the invention can be used for preventing and treating renal insufficiency, especially renal insufficiency induced or caused by hypertension, for it is well known that renal insufficiency very often accompanies hypertension and is a direct consequence thereof in the more or less long term. 
     Deterioration in renal function in patients with pre-existing renal failure is a well known side-effect during the treatment of hypertension by beta-adrenergic blocking drugs. Such effect has been reported by Dr. D. J. WARREN Am. Heart. J. (1976),91, No. 2, 265. 
     As we mentioned above, the acute and chronic oral administration of beta-blockers usually results in a reduction in effective renal plasma flow and glomerular filtration rate. The only exception is perhaps nadolol, the effects of which on the renal plasma flow depend on the mode of the administration, and the low sodium diet of the patients. Nadolol, however, does not increase glomerular filtration rate in any case. 
     The superiority of the invention is that it increases renal plasma flow in animals and in patients with or without a low sodium diet, and increases the glomerular filtration rate and sodium excretion. 
     Concerning the treatment of hypertension, subjects with normal renal function can be treated with all beta-blockers. Patients with renal impairment can be treated with nadolol or with the method of the invention. Patients with renal insufficiency can be treated only with the method of the invention. 
     The pharmaceutical composition according to the invention is preferably intended for administration by the oral route or, if desired, by the parental route. It may be presented especially in the form of plain or coated tablets, dragees, capsules, suspensions for drinking or also solutions for injection filled into ampoules, multi-dose bottles or syringes for self-injection. 
     The pharmaceutical composition according to the invention may also contain one or more excipients and diluents, binders, adhesion agents or disintegrating agents, lubricants or thickening agents. Amongst the latter there may be mentioned starches, potato starch, natural or chemically modified celluloses, methylcellulose, ethylcellulose, calcium carbonate and magnesium phosphate. 
     For solutions or suspensions, water or saline solutions are preferably used as carrier or solvent. 
     The daily dosage for adults is within the range of from 2 to 10 mg daily, preferably administered in one dose. 
     The following example illustrates the invention without limiting it in any way. 
    
    
     EXAMPLE 1 
     Tablet containing 5 mg of THPT, HCl 
     
         ______________________________________                                    
(dl)-THPT,HCl           5.000   mg                                        
stearic acid            0.490   mg                                        
microcrystalline cellulose                                                
                        33.300  mg                                        
sodium carboxymethyl starch                                               
                        3.000   mg                                        
colloidal silica        0.270   mg                                        
lactose                 37.000  mg                                        
glycerol                0.044   mg                                        
magnesium stearate      0.490   mg                                        
hydroxypropylmethylcellulose                                              
                        0.750   mg                                        
sodium laurylsulphate   0.035   mg                                        
titanium oxide          0.140   mg                                        
dicalcium phosphate     10.000  mg                                        
polyoxyethylene glycol 6000                                               
                        0.018   mg                                        
white wax               q.s.                                              
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 A finished tablet has an average weight of 91 mg.                        
 
    
     PHARMACOLOGICAL STUDIES IN DOGS 
     EXAMPLE 2 
     The renal haemodynamic effects of THPT were examined after intravenous administration of 0.05 mg/kg of the drug in normotensive conscious dogs. The glomerular filtration rate and the renal plasma flow were evaluated using the standard methods of clearance of inulin and para-aminohippuric acid (PAH). 
     In comparison to the control group, on the treated group were observed an increase in glomerular filtration rate (GFR) (inulin clearance) and a slight enhancement in effective renal plasma flow (PAH-clearance or C PAH ), without attendant decreases in plasma renin activity (PRA). An increase in urinary sodium excretion which may be related, in part, to a decrease in tubular reabsorption was also observed (Table 1). 
     
                                           TABLE 1                                 
__________________________________________________________________________
Time (min)                                                                
         0-20  20-40 40-60 60-80 80-100                                   
                                       100-120                            
__________________________________________________________________________
GFR (ml/min)                                                              
Control  50.5 ± 5.0                                                    
               54.0 ± 4.9                                              
                     51.0 ± 4.9                                        
                           53.6 ± 3.9                                  
                                 56.4 ± 5.8                            
                                       59.8 ± 6.4                      
THPT     55.5 ± 3.3                                                    
               57.3 ± 2.6                                              
                     62.8 ± 8.1                                        
                           67.7 ± 5.0                                  
                                 74.0 ± 4.9                            
                                       62.0 ± 6.6                      
         N.S.  N.S.  N.S.  p&lt;0.02                                         
                                 p = 0.057                                
                                       N.S.                               
C.sub.PAH (ml/min)                                                        
Control  193 ± 23                                                      
               197 ± 24                                                
                     194 ± 19                                          
                           190 ± 17                                    
                                 200 ± 23                              
                                       200 ± 22                        
THPT     206 ± 27                                                      
               214 ± 25                                                
                     222 ± 35                                          
                           226 ± 24                                    
                                 241 ± 26                              
                                       222 ± 27                        
         N.S.  N.S.  N.S.  p = 0.087                                      
                                 N.S.  N.S.                               
U.sub.Na V(μEq/min)                                                    
Control  63 ± 20                                                       
               62 ± 17                                                 
                     60 ± 19                                           
                           60 ± 18                                     
                                 46 ± 12                               
                                       44 ± 12                         
THPT     48 ± 12                                                       
               46 ± 10                                                 
                     50 ± 10                                           
                           74 ± 19                                     
                                 107 ± 24                              
                                       138 ± 38                        
         N.S.  N.S.  N.S.  N.S.  p&lt;0.01                                   
                                       p&lt;0.025                            
Fractional                                                                
sodium                                                                    
extraction                                                                
Control  0.86 ± 0.24                                                   
               0.87 ± 0.28                                             
                     0.76 ± 0.23                                       
                           0.78 ± 0.26                                 
                                 0.57 ± 0.13                           
                                       0.52 ± 0.13                     
THPT     0.64 ± 0.18                                                   
               0.56 ± 0.13                                             
                     0.51 ± 0.14                                       
                           0.87 ± 0.11                                 
                                 1.00 ± 0.27                           
                                       1.62 ± 0.50                     
         N.S.  N.S.  N.S.  N.S.  p&lt;0.05                                   
                                       p&lt;0.05                             
P.R.A.                                                                    
(ng AI/ml/hr)                                                             
Control  0.83 ± 0.27                                                   
               0.88 ± 0.33                                             
                     0.80 ± 0.28                                       
                           0.81 ± 0.30                                 
                                 0.83 ± 0.27                           
                                       0.80 ± 0.28                     
THPT     0.94 ± 0.22                                                   
               0.84 ± 0.19                                             
                     0.84 ± 0.24                                       
                           0.88 ± 0.34                                 
                                 1.01 ± 0.46                           
                                       1.54 ± 1.00                     
         N.S.  N.S.  N.S.  N.S.  N.S.  N.S.                               
__________________________________________________________________________
 Mean ± S.E.M.                                                         
 N.S.: Statistically not significant.                                     
 
    
     EXAMPLE 3 
     Experiments were performed during which the effects of two beta-adrenolytic agents propanolol and THPT, on renal function and plasma renin activity (PRA) were studied in sixteen conscious sodium replete dogs. In all experiments renal function was evaluated from effective renal plasma flow (RPF) and glomerular filtration rate (GFR) assessed by measurement of the clearances of para-aminohippuric acid (C PAH ) and creatinine, respectively. These parameters were measured during two 30 minute control periods, following which, two further measurements were performed over a similar time period, after intravenous administration of either propanolol (0.5 mg/kg n=8), or THPT (0.05 mg/kg, n=8), these two doses being of equivalent beta-adrenolytic activity. 
     After administration of propranolol a significant decrease in plasma renin activity and effective renal plasma flow was observed without any change in glomerular filtration rate or sodium excretion. In contrast to propranolol, administration of THPT did not result in any modification of effective renal plasma flow. However, statistically a significant increase in glomerular filtration rate and sodium (Na + ) excretion was observed. THPT also induced a significant decrease in plasma renin activity. 
     These results prove that propranolol and THPT have differing effects on renal hemodynamics in the conscious dog. 
     
                       TABLE 2                                                     
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           To      30 min.     60 min.                                    
______________________________________                                    
C.sub.PAH (ml/min)                                                        
THPT         196 ± 16                                                  
                       200 ± 16 191 ± 8                             
Propanolol   218 ± 14                                                  
                       188 ± 12 170 ± 12*                           
GFR (ml/min)                                                              
THPT         72 ± 5 81 ± 4   82 ± 4**                            
Propranolol  66 ± 2 65 ± 2   67 ± 2                              
PRA (ng.AgIml/h/)                                                         
THPT          2.2 ± 0.4                                                
                         1.0 ± 0.1**                                   
                                    0.7 ± 0.1**                        
Propranolol   2.9 ± 1.2                                                
                        1.9 ± 0.9*                                     
                                   1.9 ± 0.8*                          
Na.sup.+ Ur.(mEq/l)                                                       
THPT          70 ± 10                                                  
                        100 ± 7**                                      
                                   105 ± 10**                          
Propranolol  108 ± 18                                                  
                        95 ± 19 82 ± 20                             
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 mean ± S.E.M.                                                         
 Statistically significance:*p&lt;0,05                                       
 **p&lt;0,02                                                                 
 
    
     CLINICAL STUDY 
     EXAMPLE 4 
     The study was carried out on 20 subjects divided into 4 groups of 5 patients. 
     Group I 
     Patients suffering from hypertension and having chronic organic renal insufficiency; 
     Group II 
     Patients suffering from hypertension having a normal glomerular filtration rate; 
     Group III 
     Normal controls; 
     Group IV 
     Patients having chronic organic renal insufficiency but having arterial blood pressure figures which remained normal both when lying down and when standing up. 
     Each patient received THPT in the form of tablets for 15 days, form D 1  to D 15 . One tablet containing 5 mg of THPT hydrochloride was administered each morning at breakfast. The glomerular filtration rate and the renal plasma flow were evaluated using the standard methods of clearance of inulin and para-aminohippuric acid. Plasma renin activity and plasma aldosterone were measured by radio-immunology. These measurements were carried out on day 0 and day fifteen (D 0  and D 15 ) of the treatment and were subjected to statistical analysis. 
     Analysis of the results showed 
     (A) Hypertensive patients: 
     in patients suffering from hypertension and having chronic renal insufficiency (Group I): 
     a significant average increase in the glomerular filtration rate of 11.70% (p&lt;0.05) and 
     a significant average increase in renal plasma flow of 10.80% (p&lt;0.01) 
     in patients suffering from hypertension without renal insufficiency (Group II): 
     a significant average increase in the glomerular filtration rate of 29.71% (p&lt;0.01) 
     a significant average increase in the renal plasma flow of 34.78% (p&lt;0.01) 
     (B) Normotensive patients 
     in normal subjects (Group III): 
     an average increase in the glomerular filtration rate of 2.95% (statistically not significant=NS) an average increase in the renal plasma flow of 1.94% (N.S.) 
     in patients having chronic renal insufficiency without hypertension (Group IV): 
     an average increase in the glomerular filtration rate of 9.15% (N.S.) an average decrease in the renal plasma flow of 7.4% (N.S.) 
     With regard to plasma renin activity and aldosteronemia, a decrease in the basic values was observed after treatment whichever group was studied. The average decrease for plasma renin activity was 40% when lying down (p&lt;0.001) and 58% when standing up (p&lt;0.001); for aldosterone it was 37% when lying down (N.S) and 42% when standing up (p&lt;0.05). 
     The systolic and diastolic arterial blood pressure decreases significantly in patients suffering from hypertension. THPT is tolerated well, whether chronic renal insufficiency is present or not, and does not have any side effects so that it is safe for use. 
     Table 3 summarizes the effects on glomerular filtration rate and renal plasma flow after chronic oral administration of THPT in hypertensive or normotensive subjects with or without renal insufficiency. 
     
                       TABLE 3                                                     
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                                Renal                                     
                 Glomerular filtration                                    
                                Plasma                                    
Group of Patients                                                         
                 rate           flow                                      
______________________________________                                    
(A)  Hypertensive Patients                                                
     with chronic    Increase       Increase                              
     renal insufficiency                                                  
                     (11.70%)       (10.80%)                              
     (Group I)       (S)            (S)                                   
     without renal   Increase       Increase                              
     insufficiency   (29.71%)       (34.78%)                              
     (Group II)      (S)            (S)                                   
(B)  Normotensive Patients                                                
     normal subjects Increase       Increase                              
     (Group III)      (2.95%)        (1.94%)                              
                     N.S.           N.S.                                  
     with chronic renal                                                   
                     Increase       Decrease                              
     insufficiency    (9.15%)       (7.4%)                                
     (Group IV)      N.S.           N.S.                                  
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 S: Statistically significant                                             
 N.S.: Statistically not significant