Purpose of the study. Develop a reaction method for the identification of dexamethasone in substances, as well as in dosage forms. Methods

Introduction. Dexamethasone is widely used in medical practice, mainly for the treatment of allergic diseases. The anti allergic effect develops as a result of a decrease in the synthesis and secretion of allergy mediators, inhibition of the release of histamine and other biologically active substances from sensitized obese cells and basophiles, a decrease in the number of circulating basophils, T- and B-lymphocytes, mast cells; suppression of the development of lymphoid and connective tissue, reducing the sensitivity of effector cells to allergy mediators, inhibition of antibody production, changes in the body's immune response.
Dexamethasone is available in 0.0005 g (0.5 mg) tablets. In case of an overdose, acute poisoning can occur, which ends in death. The peculiarity of the action is a significant inhibition of the function of the pituitary gland and the almost complete absence of mineralocortico steroid activity.
Doses of 1-1.5 mg/day inhibit the function of the adrenal cortex; the biological half-life is 32-72 hours (the duration of the inhibition of the hypothalamus-pituitary-adrenal cortex system). By the strength of glucocorticoid activity, 0.5 mg of dexamethasone corresponds to approximately 3.5 mg of prednisone (or prednisolone), 15 mg of hydrocortisone, or 17.5 mg of cortisone. Daily dose for adults is 0.002-0.003 g (2-3 mg), in case of severe condition of the patient, 0.004-0.001 g (4-10 mg) is recommended. The authenticity of dexamethasone in substances is determined by the polarimetric method. Also at the expense of oxygen, instead of ethyl alcohol, the reaction is carried out in methyl alcohol with a phenylhydrazone reagent, which gives a slightly yellow color.
Purpose of the study. Develop a reaction method for the identification of dexamethasone in substances, as well as in dosage forms.
Methods. To identify dexamethasone, we took ethyl alcohol instead of methyl alcohol. To identify dexamethasone in an alcoholic solution, when isoniazid is added at a temperature of 70-800 and with benzene sulfanilamide preparations, para-aminobenzoic acid preparations, the reaction gives a persistent yellow color.
In addition, the drug, due to the oxidation of the C17 position of α-ketal (-COCH2OH) with the Fehling reagent, gives a red precipitate. The authenticity of dexamethasone in substances is determined by the polarimetric method. Also at the expense of oxygen, instead of ethyl alcohol, the reaction is carried out in methyl alcohol with a phenylhydrazone reagent, which gives a slightly yellow color.
A thin-layer chromatographic method for the analysis of the drug was studied and developed. In the alcohol-benzene system (10:1) gives an Rf value of 0.42 ± 0.002.
The developer is a 1% alcohol solution of isoniazid with acidified sulfuric acid, which gives a yellow color when heated.
The developed identification methods can be used for substances and medicinal forms, as well as to identify the drug in biological objects (in urine and blood).
Results and discussions. Dexamethasone gives a yellow color with isoniazid, norsulfazole and anesthesin reagents. In the TLC method, the following results of dexamethasone were obtained: with a solution of ethyl alcohol Rf-0.64, with chloroform 0.60, with BAW (butanol-acetic acid-water) and with Alcohol-benzene (10:1) Rf-0.42.
Conclusion. Identification reactions of dexamethasone in substances and in tablets with isoniazid reagent, as well as with preparations containing primary amine groups developed.