This is a word sometimes applied to drugs which arrest fermentation.

Anthelmintics are drugs which kill such parasitic worms as infest the alimentary canal. Three kinds only are commonly met with in the temperate zone.

(1) Tape-worm ( Taenia solium and Taenia mediocanellata). Anthelmintics: Aspidium (mostly used), Oleum Terebinthinae, Kamala, Cuisso, Granatum, and Pepo..

(2) Round-worm (Ascaris lumbricoides). Anthelmintics: Santonin, and Spigelia and Senna.

(3) Thread-worm (Oxyuris vermicularis). Anthelmintics: Rectal injections of salt water, infusion of quassia, solutions of iron salts, or diluted oil of turpentine. It is doubtful whether these drugs (except turpentine) relieve the patient by killing the thread-worms which inhabit the rectum, or merely, by removal of mucus, render this part unfit for them. It is probable that rectal injections are useless. Large soap and water enemata, the patient being in the knee chest position, give the best results. (Whittaker.).

Anthelmintics for the tape or round-worm should be given when the alimentary tract is empty. Hence it is a good plan to give a dose of castor oil a few hours before the anthelmintic, so as to ensure that the drug comes in contact with the worm. To expel the dead parasite a purgative should be given a few hours after the anthelmintic. Castor oil should not be used if aspidium has been administered. Purgatives used for this purpose are called Vermifuges. Vermicide is a term sometimes applied to drugs which kill intestinal entozoa.

Antiparasitics or parasiticides are substances which destroy parasites. The term is usually applied to those which destroy parasites infesting the skin.

(1) For the various forms of tinea the following are used: Mercurial preparations, especially the oleate, tincture of iodine, glycerite of carbolic acid, an ointment of pyrogallic acid, a boric acid lotion, a salicylic acid lotion, acidum sulphurosum, formaldehyde and thymol; and if the patches are small, severe irritants, as croton oil, cantharides, and chrysa-robin ointment. Tinea versicolor never requires severe irritants.

(2) As a parasiticide for ilch, sulphur ointment is generally used. Balsam of Peru and Styrax are also effectual.

(3) Pediculi vestimentorum will be killed by any mild parasiticide. Unguentum Staphisagriae unofficial; 1 part powdered seed, 2 parts each, olive oil and lard, is often used.

(4) Pediculi capitis and pediculi pubis are also easily killed by mild parasiticides; mercurials are commonly employed, so also is Unguentum Staphisagriae.

Antiperiodics are drugs which arrest the return of diseases which recur periodically. Some, and probably all, act as direct poisons to the micro-organism causing the disease.

They are cinchona bark, quinine and its salts (by far the most powerful), cincbonine, arsenous acid, eucalyptus, hydrastis, salicin, salicylic acid and berberine. They are used for all forms of intermittent fever and neuralgia.