Also known as arsenobenzol, "606", and arsenophenolamin hydrochlorid, is 3-diamino-4-dihydroxyl-l-arseno benzene hydrochlorid. Corresponds to 31.57 per cent, arsenic (As).

Properties : Salvarsan occurs as a yellow, crystalline, hygroscopic powder, very unstable in air. It is soluble in water, yielding a solution with an acid reaction.

Action and Uses : Salvarsan is useful as a specific remedy for syphilis in all stages, but is the more efficient the more recent the infection. It is especially indicated in the primary stage; in the later stages it should be given in repeated doses, in conjunction with mercurial courses. In malignant syphilis, which resists mercury, it is often efficient.

Salvarsan is efficient in the various spirillar diseases such as relapsing fever, Vincent's angina, etc. In Vincent's angina local applications of the powder have been found useful, in addition to the intravenous administration. The drug administered intravenously cannot reach the spirilla embedded in the necrotic tissue of the throat.

It has been recommended as a substitute for arsenic in anemia, particularly pernicious anemia, and in diseases of the skin which are amenable to the action of arsenic. Its use in these conditions must be regarded as still experimental.

In certain cases salvarsan has produced toxic results which are equivalent to poisoning by arsenic. These have occurred more commonly after the intramuscular injections. The intramuscular injection is painful and is usually followed by a tender, inflammatory nodule, which persists for some time.

After intravenous injections certain nervous symptoms have frequently arisen which have received the name of neurorecidiv (nervous relapse). The evidence seems to show that these nervous conditions are due not to the action of salvarsan but to the increased activity of the spirochetes. They are best treated, therefore, by a specific remedy: another dose of salvarsan or a compound of mercury.

The optic neuritis which is so frequently produced by other preparations of arsenic has occurred very rarely in connection with salvarsan. The drug should be employed with great caution, however, if at all, in the presence of eye disease even when caused by syphilis.

Dosage: 0.5 gm. or 7 grains.

For subcutaneous and intramuscular injection a suspension in a neutral fluid is commonly employed. For intravenous injection a clear alkaline solution is used. The contents of a tube should be used at once after opening and under no conditions should the contents of a tube, damaged in transportation, or any remnants of the powder from previously used tubes, be employed.

The intravenous method is now recognized as the most suitable. Special care should be taken to see that the water used in making the solutions is freshly distilled and completely sterile. Various forms of apparatus have been devised to facilitate intravenous injections. Of these, some form of graduated gravity pipet connected with a tube fitted with a three-way stop-cock seems most suitable. Neosalvarsan is the name applied to a mixture of sodium 3-diamino-4-dihydroxy-1-arsenobenzene-methanal - sulphox-ylate with inert, inorganic salts. The arsenic content of 3 parts of neosalvarsan is approximately equal to 2 parts of salvarsan. Solutions of neosalvarsan are more readily prepared; otherwise its actions and uses, as well as the precautions to be observed, are the same as for salvarsan.