This section is from the "A Handbook of Useful Drugs" book, by State Medical Examining and Licensing Boards.
Acetphenetidin differs from acetanilid in containing the ethoxyl group C2H50.
Properties : Acetphenetidin occurs as white, crystalline scales or a crystalline powder. It is odorless and tasteless. It is only slightly soluble in water (1:925) but soluble in alcohol (1:12).
Incompatibilities: The same as for acetanilid.
Action and Uses: These are similar to those of acetanilid, but it is supposed to be somewhat safer. Its analgesic, antipyretic and cardiac depressant effects, like those of acetanilid, are due to the formation of paraaminophenol, and its possible advantage over acetanilid is probably due to the fact that this decomposition occurs more slowly. It is best administered in the form of powders, cachets or capsules.
Since the enactment of the Food and Drugs Act, June 30, 1906, acetphenetidin has frequently displaced acetanilid as the active agent in proprietary mixtures for the relief of headache and other pain. Its relation to acetanilid suggests similar caution in its use.
Dosage: A full dose is 0.50 gm. or 7½ grains. It is well to begin with 0.30 gm. or 5 grains, and repeat every three hours if needed for a few doses. When small doses fail to relieve headache, larger doses are also usually ineffective.