Liniments are liquid or semi-fluid preparations intended for application to the skin. They usually contain substances possessing anodyne, rubefacient, sedative, or stimulating properties exhibited in fatty or volatile media. Absorption of non-volatile substances by the skin is promoted by the employment of such vehicles as alcohol, fatty oils, mixtures of alcohol and oil, solutions of oil in alcohol and saponaceous emulsions or solutions. The skin is rapidly penetrated by alkaloids and other basic substances in the form of oleates. Oleic acid is often an advantageous vehicle for liniments, either alone or diluted with a fatty oil. Liniments, such as liniment of lime with linseed oil, used as soothing dressings to broken surfaces, are generally applied freely upon lint or any soft material, and are frequently renewed. Liniments, such as liniment of turpentine, used as local stimulants, are applied to unbroken surfaces only, with considerable friction, produced by massaging with a circular motion with the palm or fingers of the hand, according to the nature of the surface under treatment. Liniments, such as liniment of aconite, liniment of mustard, or liniment of opium, used as anodynes, counter-irritants, or sedatives, are also applied to unbroken surfaces only, in a similar manner with friction, or used as paints with a camel-hair brush. Anodyne and sedative liniments are also often applied sprinkled upon warm flannel or impermeable piline (previously prepared by dipping in hot water and wringing nearly dry); the dressing being secured with a bandage, or, if flannel is used, with oiled silk or other suitable material. A modified form of glycerin of tragacanth (see Bassorin Paste) is occasionally used as a basis for the preparation of such substances as naphthol, ammonium ichthosulphonate, and resorcin, in the form of a "drying liniment," medicaments being retained by this method in contact with the skin, by the adhesiveness of the membrane produced by the basis, when a small quantity is smeared over the affected area and allowed to dry. Liniments should be dispensed in containers, easily distinguishable by touch from those in use for medicines intended for internal administration, and, in addition to any prescribed directions, should always be plainly labelled "Not to be Taken" or "Poison."
The British Pharmaceutical Codex, 1911, was published by direction of the Council of the Pharmaceutical Society of Great Britain.