RU2070720C1 - Method of cerucal quantitative determination - Google Patents

Abstract

FIELD: analytical chemistry. SUBSTANCE: analyzed sample is treated with p-dimethylcinnamic aldehyde spirituous solution in the presence of sodium dodecyl sulfate in medium citrate buffer at pH = 1.2-4.0 followed by photometry of obtained solution at λ = 540 nm. EFFECT: improved method of assay. 13 tbl

Description

 The invention relates to the field of analytical chemistry, and in particular to methods for the quantitative determination of cerucal. This drug has a wide range of pharmacological effects. Its central effects are associated with the fact that it blocks dopamine receptors, which underlies the neurosurgical mechanism of its antiemetic effect, which inhibits the launch area of the brain stem. From the literature, data are known on the effectiveness of cerucal in the treatment of dyspepsia (repeated vomiting, nausea) in severe cardiological patients (myocardial infarction, heart failure), with vomiting in pregnant women, and with stomach and duodenal ulcers.

 Cerucal is usually well tolerated by patients, however, side effects are possible: the appearance of fatigue, drowsiness, tinnitus, dry mouth, impaired concentration, the phenomenon of parkinsonism.

 To develop a rational treatment regimen, it is necessary to establish an effective dose of cerucal individually for each patient and to optimize the regimen of his administration.

 In connection with the foregoing, the development of a method for the quantitative determination of cerucal in biological fluids is relevant.

 Known in the literature, methods for the quantitative determination of cerucal are presented in table. 1. Abroad widely use the method of high performance liquid chromatography (HPLC) as a normal phase and reversed phases.

 The positive aspects of the HPLC method for the determination of cerucal are the low detection limit, the possibility of determining cerucal in biological objects (serum and blood plasma).

 However, this method has several disadvantages: the duration of sample preparation, the use of hazard class 1 substances (methanol, etc.), which requires increased attention to safety, and the lack of supply of clinical and biochemical laboratories with expensive imported equipment.

 Spectrophotometric methods belong to the second group of determination of cerucal. The authors propose the extraction of cerucal with chloroform, followed by spectrophotometry in the UV spectral region.

Analysis of the literature indicates that the proposed methods have several disadvantages:
high detection limits of 5 μg / mg, which does not meet modern requirements of chemical analytical control,
lack of information on the selectivity of determination,
determination duration associated with extraction,
the use of expensive extractants (chloroform, ethyl acetate),
the use of additional devices in connection with the use of inert gases,
lack of information on the possibility of determining cerucal in biological fluids.

 The closest (prototype) is a method based on the use of aminophenol as an organic reagent. The determination is carried out in a medium of glycine buffer pH 1.5 1.7, the detection limit of cerucal is 10 μg / mg.

The disadvantages of this prototype method are:
the inability to determine the shares of micrograms of cerucal,
narrow pH range in which cerucal can be determined,
lack of information about the selectivity of the reaction, in particular, there is no data on the effect of drugs used for therapeutic purposes together with cerucal,
lack of information about the possibility of determining cerucal in a biological object.

 The basic method for determining cerucal is spectrophotometric, requiring the use of chloroform.

 The purpose of the invention is to lower the detection limit of cerucal, increase the selectivity of determination in the presence of other drugs, to develop a photometric method for determining cerucal in biological fluids (blood, saliva).

 This goal is achieved in that the determination of cerucal is carried out by processing the sample with an alcohol solution of p-dimethylaminocinnamic aldehyde (p-DMACA) in the presence of sodium dodecyl sulfate (DCNa) in a citrate buffer medium at pH 1.2 4.0, followed by photometric measurement of the resulting solution at λ = 540 nm.

The experiment showed that solutions containing cerucal and an organic reagent are colored yellow. The absorption spectra of binary systems in a medium of citrate buffer solutions with a pH of 1.2 to 5.0 are represented by two absorption bands. λ $\genfrac{}{}{0ex}{}{\text{1}}{\text{max}}$ = 275-λ $\genfrac{}{}{0ex}{}{\text{2}}{\text{max}}$ = 400 (tab. 2). The introduction of the third component of DCNa leads to the appearance of a bright crimson color of the solution of the systems.

The absorption spectra of 3 systems "cerucal-p-DMAKA-DSNa" are presented at all pH values by three absorption bands λ $\genfrac{}{}{0ex}{}{\text{1}}{\text{max}}$ = 275nm, λ $\genfrac{}{}{0ex}{}{\text{2}}{\text{max}}$ = 400nm, λ $\genfrac{}{}{0ex}{}{\text{3}}{\text{max}}$ = 560 nm, Δλ is 160 nm (Table 2). We have established optimal conditions for the determination of cerucal.

 The study of the dependence of the light absorption of the cerucal-n-DMACA-DSNa systems on the pH of the medium 1.2 6.0 showed that citrate buffer solutions pH 1.2 4.0 are the optimal reaction medium.

 The effect of SDMAKA on the correctness of obtaining the results of cerucal was studied (Table 3).

As follows from the results presented in table. 3, the smallest determination errors are observed in the concentration range of 0.1 to 1.0 ml of a 0.2% solution of p-DMAKA (4.56 • 10 ^-5 ДC DMAKA ≅ 4.56 • 10 ^-4 M) the concentration range on both sides there is an increase in determination errors to 15 16%. We worked further with SDMAKA = 4.56 • 10 ^-5 M.

 The optimal concentration of DSNa in the reaction system was established. Determination of cerucal content (table. 4).

Analysis of the results presented in table. 4 showed that the smallest determination errors are observed in the range of concentration DSNa 4 • 10 ^-3 ≅C _DSNa ≅4 • 10 ^-2 M.

Thus, the optimal conditions for the determination of cerucal are pH 1.2 4.0 (we used pH 2.0); With _DMAKA = 4.56 • 10 ^-5 M (0.1 ml of 0.2% solution) and With _DSNa = 4 • 10 ^-3 M (1 ml • 10 ^-1 M) (V _total. = 25 ml).

 The subordination of the cerucal n-DMAKA-DSNa system to the Bouguer-Lamberg-Beer law was studied. It was found that according to the claimed method for the determination of cerucal, it is possible to find "large" and "small" concentrations of the drug. Two ranges of detectable concentrations of cerucal have been established.

I "large" amounts of 25 300 μg / 25 ml or 1.0 12 μg / ml l = 1 cm
II "small" amounts of 3.00 40.0 μg / 25 ml 0.12 1.6 μg / ml l = 5 cm.

 The proof of the existence of a range of determined contents of cerucal is given in table. 5.

 Analysis of the data presented in table 5 showed that the errors in the determination of cerucal correspond to the photometric method and do not exceed 10% in the intervals of 25 300 μg / 25 ml (l = 1 cm) and 3.00 40.0 μg / 25 ml (l = 5 cm).

 By the detection limit, we mean the lowest content of cerucal that can be detected by this method, i.e., the lower limit of determination is 3.00 μg / 25 ml or 0.12 μg / ml (l = 5 cm).

 The literature indicates that the lower limit of the determined contents by the method of the prototype is 10 μg / ml, therefore, by the new method we were able to reduce the detection limit by 83 times, i.e. by 2 orders of magnitude. This is a significant advantage of the new technique.

 The dependence of the detection limit of cerucal on the pH of the medium, the concentration of p-DMACA and the concentration of DSNa was studied. The obtained experimental data are given in tables, respectively, 6 8.

Analysis of the data presented in tables 6-8 showed that the errors in determining the detection limit of cerucal are minimal at 4.56 • 10 ^-5 ≅С _DMAKA ≅ 4.56 • 10 ^-4 M and 4 • 10 ^-3> ≅С _ДСNa ≅4 • 10 ^-3 M in the range of 1.2 ≅pH≅4.0.

 Table 9 shows the results of the study of the selectivity of the reaction. The invention is illustrated by examples of specific performance.

 Example 1. The construction of the calibration characteristics for the quantitative photometric determination of large quantities of cerucal.

A standard solution of cerucal was prepared from an ampoule containing 10 mg of the drug in 2 ml of solution. The contents of the ampoule were quantitatively transferred into a 100 ml flask and adjusted to the mark with distilled water C _from. = 100 μg / ml.

 To build a calibration characteristic, in 7 volumetric flasks with a capacity of 25 ml, (0.1; 0.5; 1.0; 1.5; 2.0; 3.0 ml) of a standard solution of cerucal with a concentration of 100 μg / ml was measured. 0.1 ml of 0.2% DMACA solution, 1 ml of 0.1 M DSNa solution were added to each flask and the volume was adjusted to the mark with a citrate buffer solution with a pH of 2.0. The optical density of these solutions was measured on KFK-2-UXA-4.2 in a cuvette with an absorbed layer thickness of l = 1.0 cm at l = 540 nm relative to the "blank solution", which includes a citrate buffer solution pH 2.0, DMAKA and DSNa. From the obtained optical density values, the dependence A = f (c) was built.

 Law B L B is satisfied when the concentration of cerucal is in the range of 25 - 300 μg / 25 ml, with l = 1 cm.

 Example 2. The construction of the calibration characteristics for the quantitative photometric determination of low contents of cerucal.

The working solution of cerucal with C = 10 μg / ml ready-made dilution of the standard (With _Art. 100 μg / ml).

 To build the calibration characteristics of cerucal, 7 10 ml of citrate buffer solution with pH 2.0 was added to the flasks, 0.1 was added; 0.3; 0.5; 1.0; 1.5, 2.0; 2.5; 3.0; 4.0 ml; cerucal solution with C = 10 μg / ml. Added p-DMCA, DSNa as described in example 1, bring the volume to V = 25 ml, measured the optical density at l = 5 cm, relative to the "idle" solution. The experiment showed that the calibration characteristic is straightforward in the range of 0.12 1.6 μg / ml (3.00 40.00 μg / ml 25).

 Example 3. Determination of cerucal content in tablets "Cerucal" (Germany).

The analyzed tablets of the dosage forms were thoroughly ground in a porcelain mortar. Precise weights of 10 mg (0.1000 g) were quantitatively transferred to V = 100 ml volumetric flasks and dissolved in distilled H ₂ O. Aliquots of the resulting solutions (1 ml) were added to 25 ml flasks; a pH 2.0 citrate buffer solution was added; DMACA and DSNa as described in Example 1. Optical densities were measured in cuvettes with an absorbing layer thickness l = 1 cm relative to the “empty” solution. The results are shown in table 10.

 Analysis of the data given in the table allows us to conclude that the inventive method is characterized by good reproducibility and correctness.

 Example 4. Determination of the content of cerucal in donated blood. When blood was sampled for analysis, proteins were precipitated with trichloroacetic acid.

2 ml of donor blood was added to the tubes, 30 μg of cerucal was added, and mixed thoroughly. After a fixed contact time, proteins were precipitated with 2 ml of 30% trichloroacetic acid. The mixture was stirred with a glass rod and centrifuged for 5 minutes at a speed of 3000 rpm. The filtrate was poured into a measuring flask of 25 ml, was added August 10 ml buffer pH 4.0, 0.1 ml 2% solution of p-DMAC, 1 ml of 10 ^-1 M solution DSNa and adjusted to the mark with buffer. The resulting mixture photometrically analogously to example 1. The content of cerucal is determined by the calibration characteristic. The results of the determination of cerucal in donated blood are shown in table 11.

 Analysis of the data presented in table 11 indicates the correctness and reproducibility of the new methodology.

 Example 5. Determination of the content of cerucal in saliva.

 When preparing saliva for analysis, the proteins that make up the saliva are precipitated with 96% rectifier alcohol.

 The test saliva was collected in measuring tubes, 100 μg of cerucal was injected, centrifuged for 15 min at a speed of 4000 rpm to precipitate solid saliva residues. Then the filtrate was carefully transferred to another measuring tube, 2 ml of precipitant was added and centrifuged for another 5-7 minutes. The filtrate was transferred quantitatively to 25 ml volumetric flasks and 10 12 ml of a pH 4.0 buffer solution of 0.1 ml of a 0.2% p-DMAC solution were added to each filtrate. The mixture was adjusted to the mark with buffer solution and photometric as indicated in Example 1. The results of the determination of cerucal in saliva are shown in Table 12.

 As follows from the presented data, the determination error does not exceed 10%. The determination of cerucal in saliva is very promising, since it makes it easy to draw the analyzed liquid, especially in comparison with blood.

 Evidence of significant differences.

Significant differences of the developed method for the determination of cerucal are:
use as an organic reagent - p-dimethylaminocinnamic aldehyde,
the introduction of the third component of sodium dodecyl sulfate,
determination of citrate solutions in the medium in the range of pH 1.2 - 4.0.

The method developed by the authors has a number of significant advantages: firstly, it was possible to significantly reduce the detection limit by two orders of magnitude compared to the prototype method,
secondly, to increase the selectivity of the reaction, the new method allows the determination of cerucal in the presence of broad-spectrum antibiotics, anti-TB drugs, antihypertensive and nootropic drugs, as well as some cardiac glycosides,
thirdly, to expand the range of determined contents of cerucal, in comparison with known methods. For the first time, it is possible to determine small concentrations of the drug (0.12 16.0 μg / ml of the drug),
fourthly, for the first time, the possibility of determining cerucal in blood and saliva by the spectrophotometric method is shown, which is extremely important for finding the best therapeutic effect, taking into account the individual characteristics - patient sensitivity and timely maintenance of the therapeutic concentration of the drug in the body.

 The method developed by the authors is implemented on serial domestic equipment, which is equipped with analytical, biochemical and clinical laboratories of the country. The method is fast, simple, well reproducible.

 Comparison of the analytical characteristics of the proposed method with the prototype is given in table. 13.

 Analysis of the data given in table. 9, showed that all 29 drugs that can be prescribed to the patient together with cerucal do not interfere with the analytical determination of the proposed method.

Claims (1)

A method for the quantitative determination of cerucal by treating the analyzed sample with an organic reagent solution in an acidic medium followed by photometry of the resulting solution, characterized in that the acidic medium is created by adding a citrate buffer solution to pH 1.2 4.0, then p-dimethylaminocinnamic aldehyde is added sequentially to a concentration 4.56 • 10 ^{- 5} 4.56 • 10 ^{- 4} M and sodium dodecyl sulfate to a concentration of 4 • 10 ^{- 3}
4 • 10 ^{- 2} M and photometry at 540 nm.