This section is from the "A Handbook of Useful Drugs" book, by State Medical Examining and Licensing Boards.
Acetanilid is the monacetyl derivative of anilin, C6H5NH2.
Properties : Acetanilid is an odorless, crystalline powder, having a slightly burning taste. It is only slightly soluble in water (1:180), but freely soluble in alcohol (1:2.5).
Incompatibilities: Acetanilid is incompatible with spirit of nitrous ether. It forms a semiliquid mass when triturated with chloral or antipyrin.
Action and Uses: Acetanilid is analgesic, antipyretic and, in excessive doses, a cardiac depressant. These effects are probably due to paraaminophenol, into which it is converted in the body. The pulse is at first quickened and later slowed by a direct action on the heart muscle. Moderate doses have little effect on the temperature of normal animals and men, but such doses cause a marked reduction of the temperature in fever. Large doses, or small doses taken habitually, convert hemoglobin into methemoglobin and may destroy the red blood-corpuscles. In poisonous doses acetanilid produces cyanosis, abnormal reduction of temperature, coldness of the extremities and profuse sweating. In individuals with an idiosyncrasy toward the drug similar symptoms may be produced by small doses. Its use should be avoided in patients who are debilitated from any cause.
Acetanilid is effective for the relief of headache and neuralgic pain, but is not suited to the treatment of pain caused by inflammation.
Dosage: 0.20 gm. or 3 grains, It is well to begin with 0.10 gm. or about 2 grains and to repeat cautiously. Formerly mixtures of acetanilid with caffein or ammonium salts were advised on the supposition that the cardiac depression would thus be avoided, but this does not seem to be the case. Investigation has shown that acetanilid is rendered somewhat more toxic by caffein, but sodium bicarbonate renders it less poisonous. The drug should be used cautiously and only for definite indications. Acetanilid has been widely exploited in the form of varying mixtures under different names as a cure for all pain. Many so-called headache powders contain it, but its indiscriminate use in this way is dangerous. It may be administered dry in the form of powders, cachets or capsules; because of its slight solubility it should not be massed in pills or compressed into tablets unless the tablet is crushed with the teeth before swallowing or unless the tablet will disintegrate rapidly in the stomach.