Drugs which have an Antipyretic or Analgesic Action. The single official representative is Acetanilid.

Antipyrin and Phenacetin (B. P.), Exalgin, Lactophenin, Phenocoll Hydrochloride and Thallin Sulphate, none of which are official, belong to this class. Alpha- and Beta-Eucaine, local anaesthetics are considered here, for convenience.

I. Acetanilidum. Acetanilid

C6H5Nhc2h3o=l34.73. Synonyms. - Phenyl-acetamide. Antifebrin. An Acetyl denvative of Aniline.

Source

Glacial Acetic Acid and pure Aniline are heated together the excess of both ingredients is then distilled off, and the congealed residue is crude Acetanilid, which is purified by repeated crystallization from water. C6H5Nh2+Hc2h3o2=C6H5Nhc2h3o+H2O.

Characters

White, shining micaceous crystalline laminae, or a crystalline powder, odorless, having a faintly burning taste, and permanent in the air. Solubility. - In 194 parts of water, and in 5 parts of Alcohol; also soluble in 18 parts of Ether, and easily soluble in Chloroform.

Incompatibles

Potassium and sodium hydrate, and chloroform.

Impurities

Aniline and its salts.

Dose, 2 to 5 gr.; .12 to .30 gm.

Action of Acetanilid

External

It is a local haemostatic as it contracts bloodvessels when applied to them.

Internal

Blood. - With ordinary doses of this drug this fluid is unaffected, but in large doses the color is changed, from the formation of methaemoglobin. The passage of this in the urine discolors it. It causes the red corpuscles to break up and arrests the movements of the white.

Heart

This substance depresses the heart. It is not known how it does this; but what little evidence there is appears to show that it has a directly paralyzing action on the cardiac muscle.

Vessels

Acetanilid contracts the smaller vessels from direct action on their muscular coat. The blood-pressure therefore rises.

Respiration

This is not affected by ordinary doses. After toxic doses the force of the respiratory act progressively diminishes.

Kidneys

This substance is a mild diuretic. The excretion of urea and uric acid is stated to be increased by it. Large doses cause the urine to be dark from the passage of altered blood. Acetanilid is said to be excreted as aniline, but this requires confirmation.

Skin

This may produce an erythematous rash which usually

resembles that of measles or is urticarial, and it is occasionally a mild diaphoretic.

Temperature

This substance is a powerful antipyretic. It has a very slight action on the temperature of health, but it reduces it very markedly when it is raised from any cause. It was introduced into medicine for this property. We have already seen (see p. 71) how numerous are the ways in which antipyretics may act. The fall of temperature produced by this drug is not due to any action on the blood or the circulation, and it is too marked to be entirely owing to its diaphoretic action. It decreases heat production, and it is most likely that it acts directly upon that part of the central nervous system, probably upon the corpora striata, which presides over heat production. It, to a much less extent, increases heat dissipation. The result of these two actions is that the temperature falls. The proof of these statements is too long and complicated to give here, but we may mention that it is easy to show both by a calorimeter, and by the decrease of the products of the febrile destruction of tissue, such as urea, that these drugs diminish heat production. It also possesses anti-periodic properties.

Nervous System

The drug is a powerful analgesic. Ace-tanilid in large doses is said to produce first convulsions, then coma, and paralysis of motor nerves and muscles; but all these statements require further experiments.