Iodoform is triiodomethane, CHI3, and is usually prepared by the action of iodin on alcohol or acetone in the presence of alkali or alkali carbonate.

Properties : Iodoform forms a fine, lemon-yellow powder or lustrous crystals having a peculiar, very penetrating and persistent odor, and an unpleasant, slightly sweetish and iodin-like taste. It is very slightly soluble in water (1:10,000), soluble in alcohol (1 :50), and very soluble in ether (1 :5 approximately). It is also somewhat soluble in fixed oils.

Incompatibilities: It is incompatible with calomel, silver salts, chlorates and nitrites.

Action and Uses: Iodoform is a local anesthetic and an antiseptic. When absorbed through the skin or from denuded surfaces it produces intoxication, which is not evident until after the lapse of some time. When swallowed it is partly decomposed with the production of iodids, which produce their ordinary effects. Part of the drug is absorbed, however, in a form of combination not yet understood, and produces symptoms that are different from those ordinarily caused by iodin. Iodoform is slowly excreted, iodin compounds appearing in the urine for several days after a single dose.

The symptoms are restlessness, anesthesia, sometimes unconsciousness, occasional convulsions, hallucinations and delusions of persecution, rapid pulse and elevated temperature; in many cases collapse, coma and death may follow.

The physiologic actions of iodoform afford no rational basis for its internal use. Externally it is used as an antiseptic and stimulant in surgical tuberculosis. Several odorless organic compounds of iodin have been devised as substitutes for iodoform, but they are uniformly less actively antiseptic.

Dosage: 0.25 gm. or 4 grains. It is usually applied externally in the form of a dusting-powder, but may be used in the form of emulsion, as an ointment or as a surgical dressing in the form of gauze. For the relief of hemorrhoids it should be given in the form of suppositories.