Analgesic effect enhancing preparations

The present invention provides an analgesic effect enhancing preparation capable of enhancement of the effect of analgesics, the preparation comprising as an active ingredient the following amino acid composition (%); leucine 8.0-16.0, isoleucine 4.0-9.0, valine 4.0-9.0, lysine 6.0-13.0, threonine 3.0-6.0, tryptophan 1.0-2.0, methionine 2.0-5.0, cysteine 0.5-2.0, phenylalanine 3.0-7.0, tyrosine 0.2-1.0, histidine 2.0-5.0, arginine 30.0-60.0, alanine 0.5-2.0, aminoacetic acid 0.5-2.0, serine 0.2-1.0, proline 0.5-2.0, aspartic acid 0.1-0.5 and glutamic acid 0.1-0.5, calculated as free amino acids. The analgesic effect enhancing preparation of the present invention potentiates analgesic effect of various analgesics.

TECHNICAL FIELD 
The present invention relates to a preparation which enhances analgesic 
effect of analgesics. More specifically, the invention relates to a novel 
preparation capable of enhancing the effect of the analgesic when used in 
combination therewith to cancer patients or postoperative patients. 
BACKGROUND ART 
Heretofore there have been widely known and used various kinds of amino 
acid solutions supplied by means of parenteral alimentation to the 
patients such as cancer patients, postoperative patients and the like who 
are almost incapable of oral ingestion so as to achieve maintenance and 
improvement of the patients' physical fitness. Such known amino acid 
solutions are basically all alike in amino acid composition, simulating 
human milk, chicken eggs, human serum albumin, etc., and the composition 
is determined by consideration of oral alimentation to contain amino acid 
composition essential to the human body. 
Cancer patients, postoperative patients and the like usually suffer from 
serious pain and these patients generally receive analgesics. However, the 
presently known analgesics induce side effects described below and have 
the problem of low effectiveness. Since cancer patients, postoperative 
patients and the like are in seriously bad physical conditions by invasion 
and even low in their drug metabolism, the analgesics are likely to 
produce side effects and ineffective for the treatment of chronic pain due 
to the development of tolerance. 
Problems Associated With Analgesics 
(1) Narcotic and non-narcotic analgesics have problems of addiction and 
habituation. 
(2) Several problems associated with antipyretic analgesics are reported, 
for example, kidney disorder caused by phenacetin, angiopathy caused by 
acetanilide, hepatopathy caused by aspirin, tissue disorder caused by 
intramuscular injection of sulpyrine, etc. 
(3) Effective and safe drugs for treating chronic pain have not yet been 
developed due to the problem of tolerance. 
Accordingly, it is an object of the present invention to provide a novel 
pharmaceutical preparation which can enhance analgesic effect of various 
kinds of analgesics when administered to cancer patients, postoperative 
patients and the like who receive analgesics, can control the development 
of tolerance associated with the repeated administration of analgesics and 
can reduce the side effect of analgesics, to thereby provide a highly safe 
total amino acid solution. It is also an object of the present invention 
to provide a novel pharmaceutical preparation which exerts equal or 
superior nutritive effect compared to the conventional nutritive amino 
acid solutions. 
DISCLOSURE OF THE INVENTION 
The inventors conducted extensive research to attain the above-mentioned 
objects and found that the amino acid solution which was proposed as amino 
acid preparation applied to cancer patients (see Japanese Examined Patent 
Publication No. 79049/1993) having a specified composition, in which 
branched amino acids and arginine are enriched, can not only exhibit 
excellent nutritive effect when administered to the cancer patients, 
postoperative patients and the like suffering from serious pain such as 
various central pain, cancerous pain, cluster headache, cervical syndrome 
or the like by supplying sufficient protein sources (amino acids), but 
also serve as an enhancer of analgesic effect of various analgesics when 
used in combination, and further found that the dosage and tolerance of 
the analgesics can be controlled, whereby safe and highly effective 
analgesic enhancing effect can be achieved. The present invention was 
accomplished by the above-mentioned findings. 
The present invention relates to an analgesic effect enhancing preparation 
which potentiates the analgesic effect of analgesics, the preparation 
comprising as an active ingredient an amino acid composition comprising 
the following amino acids in the following amounts (wt %), more preferably 
the following suitable amounts (wt %), calculated as free amino acids. 
______________________________________ 
Amount Suitable Amount 
L-Amino acid (wt %) (wt %) 
______________________________________ 
leucine 8.0-16.0 
10.0-14.0 
isoleucine 4.0-9.0 5.0-8.0 
valine 4.0-9.0 5.0-8.0 
lysine 6.0-13.0 
7.0-12.0 
threonine 3.0-6.0 3.0-5.0 
tryptophan 1.2-2.0 1.2-1.8 
methionine 2.0-5.0 3.0-5.0 
cysteine 0.5-2.0 0.7-1.0 
phenylalanine 3.0-7.0 4.0-7.0 
tyrosine 0.2-1.0 0.3-0.5 
histidine 2.0-5.0 3.0-5.0 
arginine 30.0-60.0 
30.0-60.0 
alanine 0.5-2.0 1.1-1.7 
aminoacetic acid 
0.5-2.0 0.8-1.2 
serine 0.2-1.0 0.4-0.6 
proline 0.5-2.0 0.6-1.0 
aspartic acid 0.1-0.5 0.1-0.3 
glutamic acid 0.1-0.5 0.1-0.3 
______________________________________ 
In the above composition, L-cysteine may partly or wholly be replaced with 
L-cystine and/or L-methionine, and L-tyrosine may partly or wholly be 
replaced with phenylalanine, respectively. 
The most preferred preparation of the present invention has the following 
characteristic features: (1) the content of the branched amino acids 
consisting of L-leucine, L-isoleucine and L-valine are not less than 20 wt 
% relative to the total amino acids, and (2) the weight ratio of essential 
amino acids to nonessential amino acids except L-arginine is not less than 
30. 
The preparation of the present invention can enhance analgesic effect of 
various kinds of known analgesics. Examples of the analgesics whose 
analgesic effect can be enhanced by the preparation of the present 
invention include, for example, narcotic analgesics such as morphine, 
pethidine hydrochloride, etc.; non-narcotic analgesics such as 
buprenorphine hydrochloride, pentazocine, tramadol hydrochloride, etc.; 
antipyretic analgesics such as indomethacin, aspirin, aminopyrine, etc.; 
antispasmodic analgesics such as atropine, scopolamine, etc.; among which 
narcotic analgesics or non-narcotic analgesics are preferable. The 
analgesic effect enhancing preparation of the present invention can 
exhibit the desired enhancing effect when used in combination with the 
above-mentioned drugs. 
The amino acids used for producing the analgesic effect enhancing 
preparation of the present invention is preferably crystalline amino 
acids, and they are employed usually in free forms but not limited 
thereto. The amino acids may be used in the form of metal salts such as 
sodium salt, potassium salt, etc., inorganic acid salts such as 
hydrochloride, sulfate, etc., organic acid salts such as acetate, lactate, 
malate, etc. Further, the amino acids may be in the form of esters, such 
as methyl ester, ethyl ester, etc., which can be hydrolysed and converted 
into free amino acids in vivo. There are cases that the above-mentioned 
amino acids partly or wholly may be used in the form of N-acyl derivatives 
such as N-acetyl derivative and the like, as well as in the form of 
oligopeptides such as dipeptide or the like in which two or more amino 
acids are linked each other by peptide bonds. When each amino acid is used 
in the form other than free amino acid form, the amount should be 
determined so that the calculated amounts of each amino acid as converted 
into free amino acid fall within the range described above. Among the 
above-mentioned amino acids used for producing the preparation of the 
present invention, L-cysteine partly or wholly may be replaced with 
L-cystine and/or L-methionine, and L-tyrosine partly or wholly may be 
replaced with phenylalanine, respectively, and the desired analgesic 
enhancing effect can also be achieved by such replacements. 
The analgesic effect enhancing preparation of the present invention may be 
produced by blending the above-mentioned amounts of amino acids (or the 
derivative thereof) in the above form, formulating into a preparation 
suitable for intravenous infusion via peripheral vein, central vein, etc. 
and is administered to the patients in need of the preparation. 
Alternatively, a liquid formulation suitable for enteral administration or 
a powdery formulation which is dissolved when used is also possible. 
Similarly to the conventional amino acid preparations, the preparation may 
contain a suitable pharmaceutical carrier or diluent, and optionally 
contain a stabilizer, a pH adjusting agent, and other additives. The pH of 
the preparation is usually adjusted to 3.0-8.0, preferably 4.0-7.0. The 
concentration of total amino acids in the preparation is similar to those 
of the conventional amino acid preparations and generally varies from 
about 8.0 to about 16 w/v %. 
The dosage of the preparation according to the present invention may 
generally range from about 100 to 2000 ml per day, per adult, preferably 
about 200 to 1000 ml, in the similar manner to those of the conventional 
amino acid solutions. The dosage may suitably increase or decrease 
depending on the severity of the disease, nutriture, age, weight etc. of 
the patients who receive the preparation. The preparation of the present 
invention is preferably admixed with the conventional various kinds of 
sugars, fats, electrolytes, vitamins, etc. and is preferably continuously 
administered via central vein by TPN (Total Parenteral Nutrition). 
As a preferable embodiment using the analgesic effect enhancing preparation 
of the present invention, the preparation is administered to the cancer, 
postoperative and like patients suffering from pain in combination with 
the analgesic (combination therapy). The combination therapy using the 
analgesic is more preferably carried out by administering the analgesic, 
for example, orally, subcutaneously, intramuscularly, intravenously or 
rectally while simultaneously infusing the preparation of the present 
invention. 
The amount of the analgesic used in combination with the preparation is 
suitably determined according to the kind of the analgesic and is not 
especially limited. The dosage is almost the same as those of the 
conventionally employed analgesics and is determined to achieve the 
ordinary levels of analgesic effect. Since the analgesic effect enhancing 
preparation of the present invention achieves excellent potentiation of 
analgesic effect, the amount of the analgesic used together with the 
preparation can remarkably be reduced than conventionally while 
simultaneously exhibiting sufficiently effective analgesic effect. The 
decrease in the amount of the analgesic used leads to the reduction of the 
side effect induced by the analgesic itself. Accordingly, the preparation 
of the present invention is highly effective.

BEST MODE FOR CARRYING OUT THE INVENTION 
The present invention is further illustrated by the following Examples 
which show the process for producing the preparation of the present 
invention and the test results using the preparation. 
EXAMPLE 1 
______________________________________ 
Amino acid Amount (g/l) 
______________________________________ 
L-leucine 14.00 
L-isoleucine 8.00 
L-valine 8.00 
L-lysine 11.55 
L-threonine 5.15 
L-tryptophan 1.80 
L-methionine 4.30 
L-cysteine 1.00 
L-phenylalanine 6.30 
L-tyrosine 0.50 
L-histidine 4.50 
L-arginine 50.00 
L-alanine 1.65 
aminoacetic acid 1.25 
L-serine 0.60 
L-proline 1.00 
L-aspartic acid 0.20 
L-glutamic acid 0.20 
Total free amino acids 
120.00 
______________________________________ 
The above-indicated amounts of each amino acid in the form of crystals were 
added to the distilled water for injection and dissolved therein with 
stirring. Then to the solution was added a suitable amount of sodium 
bisulfite as a stabilizer, followed by further addition of the distilled 
water for injection until the total amount reached 11. Then a small amount 
of acetic acid was added as a pH adjusting agent to achieve the pH of 7.0. 
The thus prepared amino acid solution was aseptically filtered and poured 
into a 500 ml glass vial bottle. After replaced with nitrogen, the 
container was sealed and placed into an autoclave to carry out 
sterilization at 110.degree. C. for 40 minutes, to thereby give an 
analgesic effect enhancing preparation of the present invention which was 
formulated as an amino acid solution for infusion (total amino acids 
concentration:12.0 w/v %). 
EXAMPLE 2 
______________________________________ 
Amino acid Amount (g/l) 
______________________________________ 
L-leucine 9.60 
L-isoleucine 10.44 
L-valine 10.80 
L-lysine 15.48 
L-threonine 7.20 
L-tryptophan 2.16 
L-methionine 4.32 
L-cysteine 2.16 
L-phenylalanine 8.40 
L-tyrosine 0.60 
L-histidine 5.64 
L-arginine 36.36 
L-alanine 2.04 
aminoacetic acid 2.16 
L-serine 1.08 
L-proline 0.72 
L-aspartic acid 0.48 
L-glutamic acid 0.36 
Total free amino acids 
120.00 
______________________________________ 
The above-indicated amounts of amino acids were subjected to the same 
procedures as in Example 1, to give the analgesic effect enhancing 
preparation of the present invention in the form of an amino acid solution 
for infusion (total free amino acids concentration:12.0 w/v%). 
EXAMPLE 3 
______________________________________ 
Amino acid Amount (g/l) 
______________________________________ 
L-leucine 10.92 
L-isoleucine 6.60 
L-valine 6.60 
L-lysine 7.20 
L-threonine 3.60 
L-tryptophan 1.20 
L-methionine 2.40 
L-cysteine 0.60 
L-phenylalanine 3.60 
L-tyrosine 0.36 
L-histidine 2.40 
L-arginine 72.00 
L-alanine 0.60 
aminoacetic acid 0.60 
L-serine 0.24 
L-proline 0.84 
L-aspartic acid 0.12 
L-glutamic acid 0.12 
Total free amino acids 
120.00 
______________________________________ 
The above-indicated amounts of amino acids were subjected to the same 
procedures as in Example 1, to give the analgesic effect enhancing 
preparation of the present invention in the form of an amino acid solution 
for infusion (total free amino acids concentration:12.0 w/v %). 
EXAMPLE 4 
______________________________________ 
Amino acids Amount (g/l) 
______________________________________ 
L-leucine 15.00 
L-isoleucine 12.10 
L-valine 12.10 
L-lysine 16.80 
L-threonine 8.80 
L-tryptophan 3.20 
L-methionine 8.00 
L-cysteine 3.20 
L-phenylalanine 10.40 
N-acetyl-L-tyrosine 
1.97 
(as L-tyrosine 1.60) 
L-histidine 8.00 
L-arginine 48.00 
L-alanine 3.20 
aminoacetic acid 3.20 
L-serine 1.60 
L-proline 3.20 
L-aspartic acid 0.80 
L-glutamic acid 0.80 
Total free amino acids 
160.00 
______________________________________ 
The above-indicated amounts of amino acids were subjected to the same 
procedures as in Example 1, to give the analgesic effect enhancing 
preparation of the present invention in the form of an amino acid solution 
for infusion (total free amino acids concentration:16.0 w/v %). 
EXAMPLE 5 
______________________________________ 
Amino acid Amount (g/l) 
______________________________________ 
L-leucine 15.00 
L-isoleucine 13.28 
L-valine 13.98 
L-lysine 12.60 
L-threonine 8.96 
L-tryptophan 2.24 
L-methionine 4.64 
L-cysteine 1.28 
L-phenylalanine 5.30 
L-tyrosine 0.60 
L-histidine 3.40 
L-arginine 72.00 
L-alanine 2.88 
aminoacetic acid 1.92 
L-serine 0.80 
L-proline 0.80 
L-aspartic acid 0.16 
L-glutamic acid 0.16 
Total free amino acids 
160.00 
______________________________________ 
The above-indicated amounts of amino acids were subjected to the same 
procedures as in Example 1, to give the analgesic effect enhancing 
preparation of the present invention in the form of an amino acid solution 
for infusion (total free amino acids concentration:16.0 w/v %). 
EXAMPLE 6 
______________________________________ 
Amino acid Amount (g/l) 
______________________________________ 
L-leucine 10.85 
L-isoleucine 6.10 
L-valine 6.10 
L-lysine 8.80 
L-threonine 4.10 
L-tryptophan 1.35 
L-methionine 3.35 
L-cysteine 1.35 
L-phenylalanine 4.70 
L-tyrosine 0.60 
L-histidine 3.40 
L-arginine 24.00 
L-alanine 1.35 
aminoacetic acid 1.35 
L-serine 0.65 
L-proline 1.35 
L-aspartic acid 0.30 
L-glutamic acid 0.30 
Total free amino acids 
80.00 
______________________________________ 
The above-indicated amounts of amino acids were subjected to the same 
procedures as in Example 1, to give the analgesic effect enhancing 
preparation of the present invention in the form of an amino acid solution 
for infusion (total free amino acids concentration:8.0 w/v %). 
EXAMPLE 7 
______________________________________ 
Amino acid Amount (g/l) 
______________________________________ 
L-leucine 8.80 
L-isoleucine 5.05 
L-valine 5.05 
L-lysine 7.20 
L-threonine 3.20 
L-tryptophan 1.10 
L-methionine 2.70 
L-cysteine 0.65 
L-phenylalanine 4.00 
L-tyrosine 0.30 
L-histidine 2.85 
L-arginine 36.00 
L-alanine 1.05 
aminoacetic acid 0.70 
L-serine 0.40 
L-proline 0.65 
L-aspartic acid 0.15 
L-glutamic acid 0.15 
Total free amino acids 
80.00 
______________________________________ 
The above-indicated amounts of amino acids were subjected to the same 
procedures as in Example 1, to give the analgesic effect enhancing 
preparation of the present invention in the form of an amino acid solution 
for infusion (total free amino acids concentration:8.0 w/v %). 
EXAMPLE 8 
______________________________________ 
Amino acid Amount (g/l) 
______________________________________ 
L-leucine 11.65 
L-isoleucine 6.65 
L-valine 6.65 
L-lysine 9.65 
L-threonine 4.30 
L-tryptophan 1.50 
L-methionine 3.60 
L-cysteine 0.85 
L-phenylalanine 5.25 
L-tyrosine 0.40 
L-histidine 3.75 
L-arginine 41.65 
L-alanine 1.40 
aminoacetic acid 1.05 
L-serine 0.50 
L-proline 0.85 
L-aspartic acid 0.15 
L-glutamic acid 0.15 
Total free amino acids 
100.00 
______________________________________ 
The above-indicated amounts of amino acids were subjected to the same 
procedures as in Example 1, to provide the analgesic effect enhancing 
preparation of the present invention in the form of an amino acid solution 
for infusion (total free amino acids concentration:10.0 w/v %). 
EXAMPLE 9 
______________________________________ 
Amino acid Amount (g/l) 
______________________________________ 
L-leucine 14.30 
L-isoleucine 10.30 
L-valine 10.30 
L-lysine 13.50 
L-threonine 6.05 
L-tryptophan 2.10 
L-methionine 5.05 
L-cysteine 1.20 
L-phenylalanine 7.40 
L-tyrosine 0.55 
L-histidine 5.25 
L-arginine 58.30 
L-alanine 1.95 
aminoacetic acid 1.45 
L-serine 0.70 
L-proline 1.20 
L-aspartic acid 0.20 
L-glutamic acid 0.20 
Total free amino acids 
140.00 
______________________________________ 
The above-indicated amounts of amino acids were subjected to the same 
procedures as in Example 1, to provide the analgesic effect enhancing 
preparation of the present invention in the form of an amino acid solution 
for infusion (total free amino acids concentration:14.0 w/v %). 
EXAMPLE 10 
______________________________________ 
Amino acid Amount (g/l) 
______________________________________ 
L-leucine 14.00 
L-isoleucine 8.00 
L-valine 8.00 
L-lysine hydrochloride 
14.43 
(as L-lysine 11.55) 
L-threonine 5.15 
L-tryptophan 1.80 
L-methionine 4.30 
L-cysteine 1.00 
L-phenylalanine 6.30 
L-tyrosine 0.50 
L-histidine 4.50 
L-arginine 50.00 
L-alanine 1.65 
aminoacetic acid 1.25 
L-serine 0.60 
L-proline 1.00 
L-aspartic acid 0.20 
L-glutamic acid 0.20 
Total free amino acids 
120.00 
______________________________________ 
The above-indicated amounts of amino acids were subjected to the same 
procedures as in Example 1, to give the analgesic effect enhancing 
preparation of the present invention in the form of an amino acid solution 
for infusion (total free amino acids concentration:12.0 w/v %). 
EXAMPLE 11 
______________________________________ 
Amino acid Amount (g/l) 
______________________________________ 
L-leucine 14.00 
L-isoleucine 8.00 
L-valine 8.00 
L-lysine malate 22.14 
(as L-lysine 11.55) 
L-threonine 5.15 
L-tryptophan 1.80 
L-methionine 4.30 
L-cysteine 1.00 
L-phenylalanine 6.30 
L-tyrosine 0.50 
L-histidine 4.50 
L-arginine 50.00 
L-alanine 1.65 
aminoacetic acid 1.25 
L-serine 0.60 
L-proline 1.00 
L-aspartic acid 0.20 
L-glutamic acid 0.20 
Total free amino acids 
120.00 
______________________________________ 
The above-indicated amounts of amino acids were subjected to the same 
procedures as in Example 1, to give the analgesic effect enhancing 
preparation of the present invention in the form of an amino acid solution 
for infusion (total free amino acids concentration:12.0 w/v %). 
EXAMPLE 12 
______________________________________ 
Amino acid Amount (g/l) 
______________________________________ 
L-leucine 14.00 
L-isoleucine 8.00 
L-valine 8.00 
L-lysine 11.55 
L-threonine 5.15 
N-acetyl-L-tryptophan 
2.17 
(as L-tryptophan 1.80) 
L-methionine 4.30 
L-cysteine 1.00 
L-phenylalanine 6.30 
L-tyrosine 0.50 
L-histidine 4.50 
L-arginine 50.00 
L-alanine 1.65 
aminoacetic acid 1.25 
L-serine 0.60 
L-proline 1.00 
L-aspartic acid 0.20 
L-glutamic acid 0.20 
Total free amino acids 
120.00 
______________________________________ 
The above-indicated amounts of amino acids were subjected to the same 
procedures as in Example 1, to give the analgesic effect enhancing 
preparation of the present invention in the form of an amino acid solution 
for infusion (total free amino acids concentration:12.0 w/v %). 
EXAMPLE 13 
______________________________________ 
Amino acid Amount (g/l) 
______________________________________ 
L-leucine 14.00 
L-isoleucine 8.00 
L-valine 8.00 
L-lysine 11.55 
L-threonine 5.15 
L-tryptophan 1.80 
L-methionine 4.30 
L-cysteine 1.00 
L-phenylalanine 6.30 
L-tyrosine 0.50 
L-histidine 4.50 
L-arginine monohydrochloride 
60.47 
(as arginine 50.00) 
L-alanine 1.65 
aminoacetic acid 1.25 
L-serine 0.60 
L-proline 1.00 
L-aspartic acid 0.20 
L-glutamic acid 0.20 
Total free amino acids 
120.00 
______________________________________ 
The above-indicated amounts of amino acids were subjected to the same 
procedures as in Example 1, to give the analgesic effect enhancing 
preparation of the present invention in the form of an amino acid solution 
for infusion (total free amino acids concentration:12.0 w/v %). 
EXAMPLE 14 
______________________________________ 
Amino acid Amount (g/l) 
______________________________________ 
L-leucine 14.00 
L-isoleucine 8.00 
L-valine 8.00 
L-lysine 11.55 
L-threonine 5.15 
L-tryptophan 1.80 
L-methionine 4.30 
L-cysteine 1.00 
L-phenylalanine 6.30 
L-tyrosine 0.50 
L-histidine hydrochloride hydrate 
6.08 
(as L-histidine 4.50) 
L-arginine 50.00 
L-alanine 1.65 
aminoacetic acid 1.25 
L-serine 0.60 
L-proline 1.00 
L-aspartic acid 0.20 
L-glutamic acid 0.20 
Total free amino acids 
120.00 
______________________________________ 
The above-indicated amounts of amino acids were subjected to the same 
procedures as in Example 1, to give the analgesic effect enhancing 
preparation of the present invention in the form of an amino acid solution 
for infusion (total free amino acids concentration:12.0 w/v %). 
Pharmacological Test 1 
While performing continuous infusion of the analgesic effect enhancing 
preparation (amino acid solution) of the present invention prepared by 
Example 1, buprenorphine was administered and analgesic effect enhancing 
ability (combination effect) of the preparation of the present invention 
was evaluated by employing the following procedures. 
1. Experimental Solution, Control Solution and the Combination Substance 
A 200 ml quantity of "GE-2" (product of Otsuka Pharmaceutical Co., Ltd., a 
total electrolytes solution, whose composition and nature are indicated in 
Table 2) and 1 ml of "Otsuka MV injection" (product of Otsuka 
Pharmaceutical Co., Ltd., a multivitamin injection) were added to 100 ml 
of the analgesic effect enhancing preparation of the present invention 
(formulated as an infusion solution) having the composition and the nature 
indicated in Table 1 and 106 ml of a commercially available amino acid 
solution (control) having the composition and the nature indicated in 
Table 1, respectively, to provide an experimental solution and a control 
solution. 
TABLE 1 
______________________________________ 
analgesic 
effect 
enhancing commer- 
preparation cially 
of the available 
present injection 
invention "Prote- 
Example 1 amine 12" 
Amino acids (w/v %) (w/v %) 
______________________________________ 
L-leucine 1.400 1.138 
L-isoleucine 0.800 0.597 
L-valine 0.800 0.690 
L-methionine 0.430 0.433 
L-phenylalanine 0.630 0.974 
L-tryptophan 0.180 0.187 
L-threonine 0.515 0.504 
acetic acid .multidot. L-lysine 
1.629 -- 
acetic acid .multidot. L-lysine 
-- 0.980 
(as L-lysine 1.155 0.784) 
aminoacetic acid 0.125 1.568 
L-alanine 0.165 0.821 
L-serine 0.060 0.467 
L-aspartic acid 0.020 0.202 
L-glutamic acid 0.020 0.102 
L-histidine 0.450 (0.523) 
L-histidine hydrochloride 
-- 0.706 
L-tyrosine 0.050 0.057 
L-proline 0.100 1.063 
L-cysteine 0.100 0.023 
L-arginine 5.000 (1.230) 
L-arginine hydrochloride 
-- 1.488 
total free amino acids 
12.000 11.362 
essential amino acids (E) 
5.910 5.307 
nonessential amino acids (N) 
6.090 6.056 
E/N ratio 0.970 0.876 
branched amino acids (%) 
25.00 21.34 
total nitrogen content (mg/ml) 
25.50 18.15 
Na.sup.+ (mEq/l) 1.92 150 
Cl.sup.- (mEq/l) -- 150 
Acetate (mEq/l) 221.0 -- 
Lactate (mEq/l) 143.0 -- 
pH about 7.0 5.7-6.7 
osmotic pressure ratio* 
about 4.2 about 5 
______________________________________ 
TABLE 2 
______________________________________ 
ingredient (w/v %) GE-2 
______________________________________ 
glucose 29.2 
dipotassium hydrogenphosphate 
0.261 
sodium chloride 0.283 
potassium acetate 0.115 
calcium chloride 0.073 
magnesium sulfate 0.123 
sodium citrate 0.097 
zinc sulfate 9.6 (ppm) 
citric acid 0.165 
electrolytes composition 
Na.sup.+ 35 
K.sup.+ 25 
Mg.sup.2+ 6 
Ca.sup.2+ 6 
Cl.sup.- 35 
SO.sub.4.sup.2- 6 
Acetate.sup.- 7 
Citrate.sup.3- 20 
P (mmol/600 ml) 10 
Zn (.mu.mol/600 ml) 20 
pH 4.9 
titratable acidity 21.0 
osmotic pressure ratio* about 6 
______________________________________ 
osmotic pressure ratio * is the ratio to the physiological saline 
"Lepetan injection" (product of Otsuka Pharmaceutical Co., Ltd.) containing 
0.2 mg of buprenorphine in 1 ml thereof was used to administer 
buprenorphine hydrochloride (combination substance) as a test analgesic. 
Lepetan injection was diluted with a physiological saline when used to 
provide a concentration of buprenorphine of 0.01 mg/ml or 0.02 mg/ml and 
then administered subcutaneously using a syringe in order to give a dosage 
of 2 ml/kg. 
2. Animals and Breeding Conditions 
Forty male Wistar rats, Slc, 7 weeks of age were purchased, divided into 
the groups each consisting of five rats and housed respectively in 
polycarbonate cages. The rats were bred and conditioned for the period of 
eight days under temperature of 24.+-.2.degree. C., humidity of 55.+-.10%, 
a 12 hr light cycle (lights on from 7 a.m. to 7 p.m.) and ventilation of 
13 times per hour. During the conditioning, the rats were allowed to 
freely access solid feed (MF, Oliental Yeast Industry Co., Ltd.) and 
water. 
Then, the rats were individually housed in the metabolic cage to receive 
continuous infusion of the test solution and subjected to the following 
test. During the test, the rats were not supplied with feed and water. 
3. Experimental Group Constitution and Grouping 
Four groups each consisting of eight rats were established; two groups 
which receive the control solution were injected with 0.02 ml/kg and 0.04 
mg/kg of buprenorphine, respectively, and the remaining two groups which 
receive the experimental solution were injected with 0.02 mg/kg and 0.04 
mg/kg of buprenorphine, respectively. The test animals were selected in 
order that the results of the Randall-Selitto pain threshold test using 
right and left hindpaws measured at day 1 of the test did not vary, and 
were grouped by the stratified continuously randomized method referring to 
the values of pain threshold. 
4. Administration Regimen and Dosage of the Infusion Solution 
The rats were cannulated into the superior vena cava with a catheter and 
infused with the test solution for a period of three days. 
The dosage of each test solution was determined to give 300 ml/kg/day based 
on the body weight measured immediately after implanting the catheter. 
Since the day of the catheter implantation corresponded to a sugar 
administering day, the amount of solution dosed was reduced by half. 
5. Control of the Infusion Solution 
After Otsuka MV injection was admixed with each test solution, the scale 
mark of the syringe and the onset time were recorded. The amount of the 
solution dosed in a day was calculated by subtracting the remaining amount 
in the syringe measured at 9:00 a.m. in the next morning from the set 
amount and by referring to the dosing duration, then the pumping scale was 
re-adjusted so as to give the dosage of 300 ml/kg/day. 
6. Preparation of the Brewer's Yeast Solution and the Administration 
Thereof 
A 10% brewer's yeast suspension was prepared by suspending Brewer's yeast 
(Sigma Chemical) in a physiological saline, and each rat was injected with 
0.1 ml of the suspension subcutaneously by a syringe in the right footpad. 
7. Test Procedures 
7.1. Assessment of Analgesic Effect by the Tail-Flick Test 
According to the D'Amour-Smith method (European Journal of Pharmacology, 
236, 137 (1993)), the radiant heat tail-flick test was performed and the 
latencies of the tail-flick response time were measured using the 
Tail-Flick analgesic effect measuring device. The latency of the 
tail-flick response time was measured before implanting the catheter and 
72 hr after the start of continuous infusion and analgesic effects were 
compared between the control solution and the experimental solution. 
Next, 73 hr after the start of continuous infusion of each solution, the 
rats were injected with the brewer's yeast suspension in the right 
footpad, and two hours after the brewer's yeast injection, the combination 
substance (buprenorephine) was injected subcutaneously. Then, 1, 3 and 6 
hours after the buprenorphine injection, the latencies of tail-flick 
response time were measured and enhancement of analgesic effect was 
assessed and compared between the combination of buprenorphine plus the 
control solution and the combination of buprenorphine plus the 
experimental solution. 
7.2. Assessment of Analgesic Effect by the Randall-Selitto Test 
According to the Randall-Selitto test (European Journal of Pharmacology, 
218, 153 (1992)), the pressure required to elicit a struggle response in 
each rat was determined by applying pressure to both right and left 
hindpaws using the Randall-Selitto analgesic effect measuring device. Pain 
thresholds in the right and left intact paws were measured before 
implanting the catheter and 72 hours after the start of continuous 
infusion, and analgesic effects were compared between the control solution 
and the experimental solution. 
Next, 73 hours after the start of continuous infusion, the rats were 
injected with the brewer's yeast suspension subcutaneously in the right 
footpad, and two hours after the brewer's yeast injection, the combination 
substance (buprenorphine) was injected subcutaneously. Then, 1, 3 and 6 
hours after the buprenorphine injection, pain thresholds were measured in 
the inflamated and intact paws to assess enhancement of analgesic effect 
of buprenorphine by simultaneously administering the control solution and 
the experimental solution, respectively. 
8. Statistical Analysis 
Test data obtained were presented as means.+-.SE and were analyzed by 
Student's test. The control solution and the experimental solution were 
respectively evaluated for their analgesic effect before implanting the 
catheter and 72 hours after the start of continuous infusion, and the 
results were also compared between the two groups. Enhancement of 
analgesic effect by simultaneously administering the control solution and 
the experimental solution, respectively, was checked at 72 hr after 
continuous infusion and at 1, 3 and 6 hr after the buprenorphine 
injection. The results obtained at every measuring point were also 
compared between the control groups and the experimental groups. 
9. Test Results 
(1) Body Weights 
Changes in the rats body weights were checked with the time-course of the 
test, and the rats weights of the experimental groups were almost similar 
to those of the control groups through the observation period. 
(2) Assessment of Analgesic Effect by the Tail-Flick Test 
The results were shown in FIG. 1. In the graph, elapsed time after the 
start of continuous infusion (hour) was indicated along the abscissa and 
the response latency (second) was indicated along the ordinate. The line 
(1) indicates the results of the experimental groups receiving the 
preparation of the present invention and the line (2) indicates the 
results obtained by the control groups. In the graph, the arrow 
demonstrates the time of administering the brewery's yeast solution and 
buprenorphine, respectively. 
As indicated by the results, the start of continuous infusion did not 
produce any change in the response latencies both in the control groups 
and in the experimental groups, and even at 72 hr after continuous 
infusion, no notable difference was observed between the control groups 
and the experimental groups. 
By applying subcutaneous injection of buprenorphine at 75 hr after 
continuous infusion, the response latency was prolonged in the control 
groups receiving 0.04 mg/kg of buprenorphine, whereas in the experimental 
groups receiving 0.04 mg/kg of buprenorphine a significant prolongation of 
response latency was observed in the dose dependent manner and the latency 
values of the experimental groups were higher than those of the control 
groups. 
3. Assessment of Analgesic Effect by the Randall-Selitto Test 
The results are shown in FIG. 2 (inflamed right paw) and in FIG. 3 (intact 
left paw). 
In each FIG., elapsed time after the start of continuous infusion (hour) 
was indicated along the abscissa and pain threshold (mmHg) was indicated 
along the ordinate. The line (1) indicates the results of the experimental 
groups receiving preparation of the present invention and the line (2) 
indicates the results obtained by the control groups. In the graphs, 
arrows demonstrate the time of administering the brewery's yeast solution 
and buprenorphine, respectively. 
As is apparent from the results presented in the FIGs, there is no change 
in the pain thresholds in the control groups even by injecting 0.04 mg/kg 
of buprenorphine in both right and left intact paws at 72 hr after 
continuous infusion, as compared to the results measured before the start 
of the control solution infusion. By contrast, a significant increase or 
increasing tendency was observed in the pain thresholds in the 
experimental groups and the pain threshold values were higher than those 
of the control groups. 
In the control groups receiving 0.04 mg/kg of buprenorphine at 75 hr after 
continuous infusion, a significant increase in the response latency was 
observed only in the intact paws, as compared to the condition before 
administering buprenorphine. In the experimental groups, a significant 
increase or increasing tendency in the pain threshold was observed by 
administering 0.04 mg/kg of buprenorphine both in the intact and inflamed 
paws, and a significant increase or increasing tendency in the pain 
threshold was observed in the intact paws, and the degree of the increase 
was higher than that of the control groups. 
In view of the above results, the analgesic effect enhancing preparation of 
the present invention can achieve significant enhancement of analgesic 
effect of the analgesic. 
Industrial Applicability 
The analgesic effect enhancing preparation of the present invention can 
potentiate analgesic effect of various kinds of analgesics which are 
administered in combination therewith. The preparation can safely and 
effectively be applied to the seriously invaded patients such as cancer 
patients, postoperative patients and the like who suffer from various 
pains.