PHENACETIN, a drug crystallizing from water in colourless plates, melting at 135° C. It is soluble in about 70 parts of hot and in about 1,400 parts of cold water. It is prepared by acetyl ating para-phenetidine, or by heating para-acetylaminophenol and potassium ethyl sulphate with alcoholic soda to 150° C. It is acetyl-p-phenetidine, Para-phenetidine is prepared by treating the sodium salt of para-nitrophenol with ethyl iodide, and reducing the nitrophenetole to para-phenetidine or aminophenetole. The yield may be doubled by diazotizing para phenetidine, coupling with phenol, ethylating and reducing.
Several compounds related to phenacetin have been introduced into medicine. Triphenin is propylphenetidine ; lactophenin is lactylphenetidine ; pyrantin is para-ethoxyphenyl succinimide, salophen or saliphenin is salicylpheneti dine ; amygdophenin is mandelylphenetidine. In addition, several other derivatives have been suggested which have a greater solubility than phenacetin, e.g., phesin, which is the sodium salt
of phenacetinsulphonic acid, apolysin and citrophen (citrophenin), which are citric acid derivatives of para-phenetidin, etc.
Phenacetin is contained in both the British and United States pharmacopoeia, in the latter under the name of acetphenetidin. The dose is 5 to 10 gr. given in cachets or in suspension. When the drug is carelessly made it may contain impurities, producing considerable irritation of the kidneys. The physiological action of phenacetin consists in a sedative action on the sensory tracts of the spinal cord, and a depressant action on the heart, where it tends to paralyse the action of the cardiac muscle. Its chief therapeutic use is as an antineuralgic, and it is of service in migraine, rheumatism of the sub-acute type, intercostal neuralgia and locomotor ataxia.