This section is from the book "Materia Medica Pharmacy, Pharmacology And Therapeutics", by W. Hale White. Also available from Amazon: Materia Medica Pharmacy, Pharmacology And Therapeutics..
(Not official.)- C19H27N04HCl+H2O=386.6l. The hydrochlorate of a synthetic alkaloid having a close chemical relationship to cocaine.
By the action of one molecule of ammonia upon three molecules of acetone, triacetonamine is formed. This is then transformed into triacetona-mencyanhydrine by hydrocyanic acid. This compound when saponified becomes triacetonalkamin carbonic acid, ammonia being given off, when benzy-lated and methylated trimethylbenzoyhetramethyl - y - oxypiperidin carbonic acid - methylester or Eucaine is formed.
Permanent shining scales containing one molecule of water of crystallization. Solubility. - In about 6 parts of water.
Caustic alkalies, alkaline carbonates and ammonia.
The general action of eucaine, both in cold and warm blooded animals, consists in a marked excitation of the entire central nervous system, followed by paralysis; in toxic doses going on to death. Small doses administered to mice and rabbits cause increased reflex excitability, and increased but weakened respiratory movements. Medium doses in rabbits cause repeated tonic and clonic convulsions. The animals lie senseless on their sides, with dyspnoea, opisthotonos, and finally paresis of the posterior limbs. These phenomena are most marked when large toxic doses are administered; the convulsions return continuously, and affect all the muscles of the body. The animals finally die when the paralysis reaches the respiratory muscles. When the dose is not a fatal one, the convulsions gradually cease, the increased reflex excitability disappears, and the paresis of the hind limbs slowly improves. The effect on the central nervous system is therefore at first excitant, and later, in toxic doses, paralyzing. The paralysis is a central one, for if the sciatic nerve of a frog poisoned with eucaine is exposed, and its peripheral end irritated with the induced current, the limb reacts in a normal manner. As regards its action on the heart and the blood-vessels, the subcutaneous and intravenous injection of small and medium doses slows the heart on the average from twenty to thirty beats per minute, but without otherwise modifying the beats, or increasing the blood pressure. This effect on the pulse is caused by the excitation of the central vagus; for section of the vagi causes an immediate increase of the pulse to the normal and above it, together with an increase of the blood pressure. Death occurs from paralysis of the respiratory centres, for the heart continues to beat for some time thereafter (Vinci).
Eucaine is used in from 1 to 5 or even 10 per cent. solutions for the same purposes as is cocaine. The anaesthesia comes on somewhat more slowly, with solutions of the same strength is about equal to, and its effects last about the same time as with the latter drug. It possesses the disadvantage of causing hyperaemia of mucous membranes, and in 2 per cent. solution may irritate the conjuctiva. A 1 per cent. solution, however, does not cause any disturbance. It is preferable to cocaine in that its aqueous solutions are permanent and can be sterilized by heat without decomposition. It does not cause mydriasis nor disturbance of accommodation, nor does it dry the corneal epithelium, and further it is relatively safer, so far as circulation and respiration are concerned, than cocaine. Vinci claims that its solutions possess moderate antibacterial powers.
In order to avoid the burning sensations, pain and hyperaemia to which eucaine may give rise, a substance known as Benzoyl-vinyldiacetonalkamin hydrochlorate named Beta-eucaine (not official), a compound closely related chemically to eucaine, has been recommended. Its chemical and physiological properties, with the above exceptions, are the same. It is safe, being three and three-quarters less toxic than cocaine, does not affect the heart, and is unirritating. It does not produce, when employed in the eye, mydriasis, corneal lesions, nor disturbances of accommodation. It can be sterilized by boiling without deterioration; its solutions are permanent and do not decompose when kept. Its field is the same as that of cocaine, and it can be employed for the various operations upon the eye, nose, ears, genito-urinary tract, in minor surgery and dentistry, and for infiltration anaesthesia. For medullary anaesthesia while the aftereffects seem no greater than with cocaine the analgesia is not so uniform nor lasting. Its ease and certainty of sterilization by boiling are in its favor and some operators are strong advocates of it. It is employed in from 1/2 to 4 per cent. (saturated) aqueous solution, but of the latter not more than 30 minims; 2.00 c.c, should be employed at one time, although for a prolonged operation five times this quantity may be employed.