Methylene Blue

METHYLENE BLUE, Methylenblau, Methylenum coeruleum (CH₃)₂N C₆H₄\_C₆H₃ : N(CH₃)₂Cl, is widely used in microscopic technique because it stains cell nuclei, basophilic protoplasmic inclusions (granules, Nissl bodies in nerve cells), and the protoplasm itself (e.g., of lymphocytes), as well as mucin, in a blue color. Methylene blue containing methylene azure as a breakdown product (see Giemsa), for example, upon prolonged standing in solution or upon careful warming with alkalis, possesses pronounced metachromatic properties (see Metachromasia). So-called polychrome methylene blue (Unna) is particularly rich in methylene azure (along with another breakdown product, methylene violet). Polychrome methylene blue is prepared as follows: a 1% aqueous solution of methylene blue (100.0) with the addition of 20 cm³ of alcohol and 1 g of potassium carbonate is evaporated on a water bath to a total volume of 100 cm³. The preparation stained with such a blue (10 min.) is washed in water and differentiated in a glycerin-ether mixture (Glycerinaethermischung according to Unna) diluted 4 times with water; the section is dried; alcohol, xylene, balsam. Methylene blue, in particular methylene azure, forms true compounds with tissues and is not extracted by water; alcohol removes the stain. One of the advantages of methylene blue is that it does not overstain objects. It is widely used for vital staining; the possibility of the latter is explained by the fact that methylene blue, upon entering into a compound with certain tissues (peripheral nerves, and in lower animals also parts of the central nervous system, ganglion cells), is converted under the influence of the reducing properties of these tissues into a colorless base (leucomethylene blue). Under the influence of atmospheric oxygen, the colorless compound transitions into the usual blue, and thus the nerves can be visualized down to their smallest ramifications. Methylene blue is one of the most frequently used stains in bacteriological practice; staining of bacteria is performed with both aqueous and alcoholic solutions. The most commonly used are Löffler's blue and Manson's blue. Regarding the use of mixtures of methylene blue with eosin, see Blood. Methylene blue is widely used in clinical practice for diagnostic and therapeutic purposes. When methylene blue is administered per os, its absorption occurs in the small intestine, and excretion occurs via urine and feces, with the urine being colored green by methylene blue. The addition of methylene blue to nutrient media sharply slows down the growth of bacterial cultures. Due to its parasitotropic action, methylene blue is prescribed most often for malaria (see), especially in its quartan form, as well as for cystitis, gonorrhea, etc. Methylene blue is also used for the functional diagnosis of excretory parenchymatous organs (kidneys, liver) in order to study the excretory capacity of these organs (see Duodenal tube). With prolonged administration of methylene blue, mild symptoms of cystitis are sometimes observed, which can be prevented by the addition of nutmeg. Dosage of methylene blue: internally—0.1–0.2 pro dosi (0.3–0.5 pro die). Intravenously: 0.05 in a 1% solution.