HU195424B - Process for the production of medical solutions containing l-3,4-dihydroxi-phenil-alpha-methil-alanine - Google Patents

Abstract

The invention relates to pharmaceutical solutions, preferably injectable solutions, comprising a chelate derivative of alpha-methyl-DOPA of the formula I <IMAGE> and/or a chelate derivative of alpha-methyl-DOPA of the formula II, <IMAGE> wherein X<+> is hydrogen ion or an organic or inorganic cation.

Description

The present invention relates to a process for preparing a pharmaceutical solution containing L-3,4-dihydroxyphenyl-alpha-methyl-alanine (alpha-methyl-DOPA), preferably by intravenous injection, infusion or oral administration.

Alpha-methyl-DOPA is a known antihypertensive compound [No. 3,434,023]. U.S. Pat. The compound is usually administered in the form of tablets to patients with hypertension, but in some cases oral solutions or intravenous injection or infusion may be required.

No. 3,526,698. A stable aqueous suspension containing alpha-methyl-DOPA is known from U.S. Pat. It is for oral administration only and its absorption is less favorable than that of the solution.

No. 3,230,143. The solution known from U.S. Pat. No. 4,800,198 contains the hydrochloride of the ethyl ester of alpha-methyl-DOPA as an active ingredient, which, upon administration, is converted into the active compound in the body. This known solution can be administered intravenously, but only at high dilution.

No. 4440/83, published Aug. 28, 1985, under T / 35954. Hungarian patent application discloses an aqueous solution, both intravenously and orally, containing 1-5% alpha-methyl-DOPA, 15-75% solubilizing agent, 20-80% water and 0.1-1095% additive. its value is 3-5. Polyvinylpyrrolidone or glycerol are used as solubilizers.

However, the relatively strong acidity of the above known formulation is disadvantageous for intravenous administration. Therefore, it is an object of the present invention to provide neutral pharmaceutical solutions.

It has been found that the above object is achieved if 1-15% of L-3,4-di-hydroxy-phenyl-alpha-methylalanine and 0.1-% of an aqueous solution of 0.2-3.0% by weight of the pharmaceutical solution of boric acid. Addition of 2% additive, where indicated amounts are based on the final weight of the pharmaceutical solution, to a pH of 7-8.5 by addition of base, water and / or saline and / or water miscible, if desired. a pharmaceutically acceptable organic solvent is added up to the final weight of the solution and the solution is subjected to filtration, preferably ultrafiltration.

The present invention is based on the discovery that alpha-methyl-DOPA forms complexes with boric acid which are highly soluble in solvents such as water.

The formation of these cyclic chelate complexes is illustrated in Schemes A and B. With an equimolar amount of boric acid, the compound of formula (I) is formed, with less boric acid, the compound of formula (II) or a mixture of the compounds of formula (I) and (II) is formed. In the formulas, X is a hydrogen ion or an organic or inorganic cation. It has now been found that compounds of Formula I and Formula II wherein X is a hydrogen ion are medium-acidic salts which are separable, generally not required in the process of the present invention, and highly soluble in water. On the side, of course, there is a balance between complex compounds, boric acid and alpha-methyl-DOPA.

The base of the process of the invention may be both inorganic and organic bases. Preferably, a base which is well soluble in water and physiologically tolerable is used. Sodium hydroxide and potassium hydroxide are preferably used.

The additive is, for example, an antioxidant such as sodium pyrosulfite, sodium bisulfite or sodium bisulfite, a bactericidal agent such as alkyl p-hydroxybenzoate, and the like. may. More than one additive may be used.

Examples of the water-miscible pharmaceutically acceptable organic solvent are ethanol, isopropanol, ethylene glycol, glycerol and the like. employed.

In preparing an intravenous solution, water or physiological saline is preferably used to adjust this final weight and the pH is generally adjusted to 7.0-7.6.

When preparing a solution for oral administration, the final weight of the solution may be adjusted with water and / or a water-miscible pharmaceutically acceptable organic solvent. An aqueous sorbitol solution may also be used for this purpose to improve the taste of the solution. The pH is adjusted to 7-8.5. Since the pH of the solution for oral administration is not as critical as for intravenous injection, a pH of 8-8.5 is acceptable.

In the process according to the invention, the additive may be added to the solution after the pH adjustment and the pH adjustment may be repeated after the final solution weight has been adjusted.

For intravenous or infusion administration, the solution, preferably pH 7.0-7.6, is converted into a sterile solution in a manner known per se, for example by passing through a microporous filter and / or by heat sterilization. The sterile solution is kept out of the air until use, for example in sealed glass ampoules.

The acute toxicity of the injectable formulation of Example 2 was determined in 10 mice of 5 males and 6 females from CFLP strain white mice weighing 18-22 g. The test solution was administered intravenously to the animals. After treatment, a 14-day follow-up was performed. The animals were fed tap water and standard mouse food ad libitum. By comparison, the above assay was also performed with 1% saline in alpha-methyl-DOPA. (For the latter, it should be noted that although a 1% aqueous solution can be prepared from crystalline alpha-methyl-DOPA, it is unstable and decomposes within 1-2 hours. However, the freshly prepared solution can be used for testing purposes.)

The LD ₅ o values included in Table 1.

As can be seen from Table 1, the toxicity of the composition according to the invention is practically the same as that of a freshly prepared solution of azalamphyl-DOPA and is consistent with the literature LD _{50 of} 1700 mg / kg.

The antihypertensive effect of the formulation of Example 2 was performed on anesthetized Wistar rats weighing 200-250 g. Arterial blood pressure was measured through an arterial carotid polyethylene cannula using an electromometer. The test substance was administered at a dose of 20 mg / kg via a cannula connected to the jugular vein of the vein and immediately prior to administration, and blood pressure was measured 5, 15, 30 and 60 minutes after administration. For comparison, blood pressure depression was also determined with freshly prepared saline containing 1% alpha-methyl-DOPA. Table 2 shows the blood pressure values, the change from the pre-dose blood pressure values.

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Table 1

Acute toxicity in mouse.

Test solution Dose, mg / kg Number of dead / treated animals mortality % LD5 0 mg / kg Male Female Altogether Example 2 3.8% solution 380 0/5 0/5 0/10 0 760 0/5 0/5 0/10 0 1000 0/5 0/5 0/10 0 1240 0/5 0/5 0/10 0 1520 0/5 0/5 0/10 0 Above 1520 1% solution of alpha-methyl-DOPA 1240 0/5 0/5 0/10 0 physiological saline 1520 0/5 0/5 0/10 0 Above 1250

p values of significance. The measured blood pressure average is given together with the standard deviation, for other values and for the calculated changes.

Antihypertensive effect in rat iv. Table 2

Measurement just before injection, 0 minutes 5 15 minutes into the; 30 after the broadcast 60 Example 2 Solution Blood pressure, kPa Change in blood pressure, kPa P 17.50 ± 0.30 16.26 ± 0.51 - 1.24 + 0.25 0.05 15.60 ± 0.66 -1.90 ± 0.41 0.05 14.80 ± 0.61 -2.70 ± 0.42 0.05 14.26 ± 0.65 - 3.24 ± 0.39 0.05 1% solution of α-methyl-DOPA in physiological saline Blood pressure, kPa Change in blood pressure, kPa 15.60 + 1.48 14.93 ± 0.86 0.67 + 1.73 15.23 ± 0.41 0.37 ± 1.34 14.93 ± 0.50 0.67+ 1.37 13.42 ± 0.76 2.18 ± 1.69

5 minutes after administration, the blood pressure of anesthetized rats was significantly reduced. At 35 s, this effect stabilized over a 60-minute study period. The decrease in blood pressure was statistically significant. It is observed that the decrease in blood pressure occurs within a shorter period of time and is greater than that of the comparatively otherwise unstable 43% 1% solution. Similar reductions in oral blood pressure were observed at a dose of 250 mg / kg, ie. 12.5 times the dose of alpha-methyl-DOPA.

The adrenergic receptor activity of the solution of Example 2 and the above comparative solutions was tested in isolated rat iron deferens by electrical stimulation.

Iron deferens were isolated from rats weighing 140-180 g, according to Henderson et al., Br. J. Pharm., 46, 764-766 (1972)] and Hart et al., Br. J. Pharm., 66, 361-363 (1979)]. The organ was continuously suspended in a 4 ml organ vessel according to Benett and Stoekley [Br. J. Pharm., 50, 453 (1974)]. The current pulses used for the pacing were as follows: 50 V voltage, 0.1 Hz frequency, 1 ms duration. When the magnitude of the electrical stimulation contractions did not change, a cumulative dose-effect curve was obtained with the solution of Example 2 or with fresh saline containing 1% alpha-methyl-DOPA. Based on the size of the contraction immediately preceding dosing, the degree of inhibition was calculated and the concentration providing 50% inhibition was determined (IC ₅₀ ).

The C50 values obtained for the two types of test solutions are shown in Figure 3.65

is shown in the table. Table 3 Test solution IC50 mol / liter Example 2 3.8% solution 2.81. 10 ' ² 1% solution of alpha-methyl-DOPE physiological saline 3.87. 10 ' ²

It is apparent from the data in Table 3 that the solution according to the invention at lower concentrations provides the same effect as the saline solution used for comparison.

The stability of the solution prepared in Example 1 at 25 ± 2 ° C in a white vial for 90 days was tested. At the beginning of the test, and at regular intervals, the pH and specific rotation of the solution were measured, the color of the solution was evaluated, and TLC analysis was also performed. For the latter, a Kieselgel GF _2S 4 layer (manufactured by Merck) was added dropwise with 5 μΐ of the test solution and a mixture of 60% v / v n-butanol, 15% v / v glacial acetic acid and 25 v / v water was used.

The solution level, specific rotation and pH are shown in Table VI. It was determined by direct measurement according to the Hungarian Pharmacopoeia. The results are shown in Table 4.

It is clear from Table 4 that the solution of Example 1 did not change over the 90 days of storage.

The pharmaceutical solutions of the present invention have sufficient stability. Good absorption 3

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Table 4

Stability of the solution of Example 1 at 25 ± 2 ° C

Storage time, day Purity by thin layer chromatography Solution- color Specific rotation [a] ²⁰ pH 0 (storage beginning) unified Zo-l -19.6 7.5 14 unchanged Zo-I -19.5 7.5 20 unchanged ^z 0-l -19.5 7.45 50 unchanged Zo-l -19.8 7.5 60 unchanged Zo-l -19.8 7.5 90 unchanged Zo-l -19.8 7.45

therefore, the antihypertensive effect is shorter after administration than the tablets containing alpha-methyl-DOPA.

The complex compounds of formulas I and II present in solutions have the same toxicity as alpha-methyl-DOPA. Solutions for intravenous injection have a near neutral pH and are therefore beneficial to the body.

The invention is illustrated in detail by the following examples.

Example 1 0.6 g of boric acid is dissolved in 1 ml of distilled water with heating, and 0.02 g of sodium pyrosulfite and 2.26 g of crystalline alpha-methyl-DOPA (containing 1.5 mol of crystalline water) are added under constant stirring. Adjust the pH to 7.4 ± 0.2 with 5% sodium hydroxide solution while measuring the pH with an electric pH meter. The solution is then made up to 100 ml with distilled water, the pH is checked again, adjusted if necessary, passed through a microporous filter, filled into 10 ml ampoules, sealed and sterilized at 100 ° C for 30 minutes. In this way, a solution containing 2% of the active ingredient is injected intravenously.

Example 2

The procedure described in Example 1 was followed except that 1.14 g of boric acid and 4.28 g of crystalline alpha-methyl-DOPA were used. An intravenous injection solution containing 3.8% of the active compound is obtained.

Example 3 2.7 g of boric acid are dissolved in 1 ml of distilled water and 0.2 g of sodium pyrosulphite and 16.95 g of crystalline alpha-methyl-DOPA (containing 1.5 mol of crystalline water) are added to the solution with stirring. . The pH is adjusted to 8 + 0.5 by the addition of 10 7 N sodium hydroxide solution and the solution is made up to 100 ml with distilled water. This gives a solution containing 15% of the active ingredient which can be administered orally. The solution is kept in a stoppered glass vial or plastic bottle until use.

Example 4

The procedure described in Example 3 was followed by the addition of 50% aqueous ethanol to 100 ml. An oral solution is obtained.

Claims (4)

CLAIMS 1. A process for the preparation of a pharmaceutical solution containing L-3,4-dihydroxyphenyl-alpha-methylalanine, preferably for intravenous injection, infusion or oral administration, characterized in that 0.2 to 3.0% by weight of the pharmaceutical solution. 1% to 15% L-3,4-Dihydroxyphenyl-alpha-methylalanine and 0.1% to 2% of an aqueous solution of% boric acid in the amounts indicated refer to the final solution of the pharmaceutical solution, base by adding pH 7 to 8.5, adding water and / or physiological saline and / or water-miscible pharmaceutically acceptable organic solvent, if desired, to the final solution, and The solution 40 is subjected to filtration, preferably ultrafiltration. 2. A process according to claim 1 wherein the base is an inorganic base. 3. A process according to claim 2 wherein the inorganic base is sodium hydroxide, preferably in aqueous solution. The method of claim 1 for preparing a solution for intravenous injection or infusion, wherein the pH is adjusted to 7.27.6 by addition of a base.