PHENACETIN, C 2 H 6 O-C 6 H 4 -NHCOCH 3 (para- acetaminophenetol), a drug prepared by acetylating para-phenetidin, or by heating para-acetylaminophenol and potassium ethyl sulphate with alcoholic soda to 150 C. Para-phenetidin is prepared by treating the sodium salt of para-nitrophenol with ethyl iodide, and reducing the nitrophenetol to para-phenetidin or aminophenetol. The yield may be doubled by diazotizing para-phenetidin, coupling with phenol, ethylating and reducing:
EtO-C 6 H4-NH 2 ->EtO-C6H4-N 2 OH-}EtO-C 6 H4-N 2 -C 6 H-OH-> EtO-C 6 H4-N 2 -C 6 Hi-OEt-^2EtO-C 6 H 4 -NH 2 .
It crystallizes from water in colourless plates, melting at 135 C. It is soluble in about 70 parts of hot and in about 1400 parts of cold water.
Several compounds related to phenacetin have been introduced into medicine. Triphenin is propylphenetidin; lactophenin is lactylphenetidin; pyrantin is para-ethoxyphenyl succinimide, EtO-CeHrNlCO-CHj];!; salop'hen or saliphenin is salicylphenetidin; amygdophenin is mandelylphenetidin. In addition, several other derivatives have been suggested which have a greater solubility than phenacetin, e.g. phesin, which is the sodium salt of phenacetin sulphonic 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 grs. 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. Upon the bodily heat it exercises a marked effect, decreasing the action of the heat-producing centre as well as increasing the dissipation of heat, and thus causing a marked fall in temperature. In toxic doses the blood becomes dark and blackish from the formation of methaemoglobin, and the urine is changed in colour from the passage of altered blood. The chief therapeutic use of phenacetin is as an antineuralgic, and it is of service in migraine, rheumatism of the sub-acute type, intercostal neuralgia and locomotor ataxia.
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)