In this connection reference may be made to the large number of synthetic organic products which have been introduced into medicine during the past few years. The investigation of the constitution of the alkaloids has served to show in many cases to what particular molecular grouping the physiological action of the drug is mainly due, and this has led to the production of substances containing these groups, but not necessarily existing as natural products. Among these may be mentioned _antipyrin_, a derivative of the pyrazol group, discovered by Knorr in 1883, and of which upwards of 17,000 kilos, of the approximate value of £35,000, were produced in 1899. This substance is a _phenyl-dimethyl-pyrazolone_.
_Acetanilide_ C6H5NH.COCH3, an aniline derivative, was discovered by Gerhardt in 1853. _Phenacetin_ is a derivative of _para_-aminophenol:
An extraordinary number of synthetical soporifics have been introduced at various times during recent years—_e.g._, _chloral hydrate_, _veronal_, _sulphonal_, _trional_ and _tetronal_, etc. The three last-named substances are closely related, as the following formulæ indicate:
CH3 CH3 \ \ C(SO2C2H5)2 C(SO2C2H5)2 / / CH3 C2H5 Sulphonal. Trional.
Sulphonal is prepared by the oxidation of a substance obtained by the combination of acetone and ethylmercaptan. _Veronal_ is an ethyl compound of barbituric acid, obtained by the condensation of urea and diethyl malonyl chloride:
Attempts have been made to connect the physiological working of local anæsthetics with particular constitutional groupings, as, for example, in cocaïne; and these have led to the introduction of such substances as the _orthoforms_, _nirvanine_, _stovaïne_, _alyhine_, _novocaïne_, and _adrenaline_ into medicine. Adrenaline, used in conjunction with cocaïne, has proved itself a most valuable agent in producing what is called _lumbal anæsthesia_, whereby large sections of the lower half of the body may be rendered completely insensitive to pain.
The study of the putrefactive changes of albuminous substances of animal origin, induced by the activity of micro-organisms, has revealed the existence of a number of basic nitrogenous compounds, some of which are highly poisonous. These were classed by Selmi under the generic name of _ptomaines_ (πτῶμα, a corpse). Brieger found that the typhoid bacillus yielded a poisonous substance—_typhotoxine_, and that the bacillus of tetanus forms a highly toxic basic body, _tetanine_. All the ptomaines, however, are not poisonous. Some of them, like _choline_ (χυλὴ, bile)—originally discovered by Strecker in bile, in the brain, in yolk of egg, and now found to be among the products of the putrefaction of meat and fish—have been known for some time past. Choline was first synthetically prepared by Wurtz. _Neurine_ (νεὺρον, nerve), a derivative of brain substance, is related to choline, and is readily transformed into it, but differs from it in being very poisonous. It has been synthesised by Hofmann and by Baeyer. Another of the so-called corpse-alkaloids—_cadaverine_—has been synthetically formed by Ladenburg. Schmiedeberg and Kopp isolated the poisonous principle of the fungus _agaricus muscarius_, which they named _muscarine_. It occurs with choline, from which it can be readily obtained, among the products of the putrefaction of flesh, as well as in many fungi.