From Big Medical Encyclopedia

NITRATES — salts and nitric acid ethers. Natural N. in the form of sodium salts, potassium, calcium, ammonium (saltpeter) are widely applied in agriculture as fertilizer, many N. apply during the dyeing, in match, in glass productions, to receiving explosive substances and production of alarm rockets. Potassium nitrate is applied to conservation of meat and preparation of other products. Organic N. widely use as pharmaceuticals. Large deposits of saltpeter are available in the USSR, the USA, Peru, India and other countries. N receive by influence nitric to - that on alkalis or carbonic salts, metals or their oxides.

N.'s most the colourless crystals having high hygroscopicity (except N. of silver and potassium); well rastvorima in water. At N.'s heating easily otshchei-lyat oxygen therefore they are strong oxidizers.

In trace amounts of N. contain in water and the soil, being end products of a mineralization of nitrogen-containing organic matters (see. Metabolism and energy, circulation of nitrogen ). In pure natural waters N.'s maintenance does not exceed 0,1 mg/l. N.'s maintenance in subsoil waters sharply increases in places where apply fertilizers. The increased N.'s maintenance in water and the soil can demonstrate also their pollution in the past economic and household waste. In this case simultaneous presence of N. and ammonia at water and the soil demonstrates that process of a mineralization of organic matters in them is not finished yet and considerable bacterial pollution can take place.

According to GOST «Drinking Water» N.'s number in water shall not exceed 45 — 50 mg/l. The use of water with high content of N. can cause in babies methemoglobinemia (see), manifestations a cut are persistent cyanosis, an asthma, sometimes spasms, the lethal outcome is possible. Similar cases were observed during the use of the water containing a large number of N. for preparation of children's nutritious mixes. At children of advanced age and adults similar acute toxic manifestations are not observed, however the maintenance of a methemoglobin in blood can increase that is a consequence of ability of N. to be recovered in an organism to nitrites (see).

In total N. possess irritant action on skin, causing its reddening, an itch, formation of lishayevidny thickenings of skin. The dust containing big concentration of N. causes irritation of a mucous membrane of respiratory tracts; at long influence on working dust of gunpowder (mix of potassium nitrates, sulfurs and coal) ulcerations and a perforation of a nasal partition were observed.

N.'s definition in free air, water and the soil is made on an ion nitric to - you are (N03)-1.

Respirators like «Petal», protective clothes and gloves, protective ointments and paste (HIOT type) are applied to protection of a respiratory organs against the dust containing N.; the dignity is necessary. control of sources of drinking water supply; control of N.'s maintenance in drinking water and preserved foods and prohibition of their use at the increased N.'s maintenance

Use of nitrates in medicine

Most often drugs H. are used for treatment of coronary heart disease.

The mechanism of anti-anginal action of N. in spite of the fact that they are applied long ago, is insufficiently clear. In the past different explanations were offered. Idea of direct myotropic (spasmolytic) effect of nitrates on coronary vessels is the most reasoned owing to what inflow of blood to a cardiac muscle increases and supply with its oxygen improves. This point of view did not lose the value and still.

The mechanism of action of N. is caused by two factors. Possessing myotropic spasmolytic action, N. expand peripheral vessels and reduce venous return of blood to heart, and also lower the peripheric resistance of vessels. It is resulted by unloading of a myocardium and its work on overcoming resistance of emission of blood decreases. A metabolic cost of heart goes down, vnutrimio-cardial tension at the same time decreases and compression of coronary arteries decreases that leads to reduction of ischemia and improvement of oxygen balance of heart. Besides, N. have the central effect on a myelencephalon, suppressing a painful impulsation from the ischemic center in heart, release monoamines from labile stocks. It is shown that in oppression of a sympathetic tone under the influence of N. major importance belongs to activation by free monoamines of processes of the descending braking of a myelencephalon.

Drugs H. are distinguished on the speed of approach and duration of anti-anginal effect: drug of bystry, but short action is nitroglycerine (see), long — aerinite (see), Nitrosorbidum (see), and also depot drugs (Sustac, etc.). The effect after reception of nitroglycerine occurs in 1 — 2 min. and proceeds up to 15 — 20 min., within 45 min. drug is completely removed from an organism. Along with antian-ginalny action nitroglycerine has ability to expand vessels of internals, a brain, retina of an eye. Depots drugs represent Tabulettaes Nitroglycerini, two-piece: outside, containing a portion bystrovsasyvayu-shchegosya nitroglycerine (action comes in 10 min.), and internal, supporting the fraction of nitroglycerine which is slowly soaking up in intestines (the effect is shown within several hours). Pill of depot drugs is taken inside, but not under language, N. with slow and long action is appointed for the prevention of attacks of stenocardia and systematic therapy of coronary heart disease. Effect of aerinite is shown in 30 — 45 min. and continues within 4 — 5 hour, and Nitrosorbidum at intake comes in 5 — 15 min. and 3 — 5 hour last. Action of Nitrosorbidum unlike aerinite develops more gradually that is caused by strong binding of drug proteins of a blood plasma. Aerinite is well transferred and well soaked up in went. - kish. path. The by-effects arising at use of nitroglycerine (a headache, dizziness, a sonitus) at purpose of aerinite and Nitrosorbidum develop seldom and are less expressed. Nitrosorbidum is appointed also at the diseases which are followed by spasms of peripheral vessels.

Contraindication for N.'s use is increase in intraocular pressure, low arterial pressure.

Bibliography: Harmful substances in the industry, under the editorship of N. V. Lazarev and I. D. Gadaskina, t. 3, page 110, L., 1977; Yershov V. P. Occupational health in production of mineral fertilizers, page 38, M., 1974; Kaverina N. V., Rozonov Yu. B. and Chichkanov G. G. Modern aspects of pharmacology of anti-anginal means, M., 1980; Clinical pharmacology, under the editorship of V. V. Zack owl, page 188, M., 1978; Marzeev A. M. and Zhabotinsky V. M. Utility hygiene, M., 1979; N. I. Roosters, etc. About water and nitrate a methemoglobinemia at children and adults, the Gigabyte. and dignity., No. 3, page 14, 1972; Subbotin F. N. Nitrates of drinking water and their influence on formation of a methemoglobin, in the same place, No. 2, page 13, 1961; Pharmacology of monoaminergichesky processes, under the editorship of V. V. Zakusov and N. V. Kaverina, M., 1971; The pharmacological basis of therapeutics, ed. by L. S. Goodman a. A. Gilman, p. 806, N. Y. a. o., 1975; S o 1 1 m a n n T. A manual of pharmacology and its applications to therapeutics and toxicology, Philadelphia — L., 1957.

A. V. Roshchin; G. V. Kovalyov (pharm.).