Filix Mas, B.P. Male Fern.
Male fern or Aspidium, U.S.P., consists of the dried rhizome of Aspidium Filix-mas, Swartz (N.O. Filicineae), a fern indigenous to Great Britain. The rhizome is collected late in the autumn, divested of its roots, leaves, and dead portions, and sometimes sliced longitudinally to facilitate drying. The rhizome occurs in pieces from 7.5 to 15 centimetres in length, and from 2 to 2.5 centimetres in diameter. It is covered with the hard, persistent, curved, angular, dark brown bases of the petioles, which bear numerous brownish membranous hairs. Externally, the rhizome is brown; internally, green, becoming brown on long keeping. Transverse sections of both rhizome and petiole should exhibit about eight steles arranged in a diffuse circle. The membranous hairs consist of elongated cells, and bear on the margin, simple hair-like processes, each of which consists of two parallel and contiguous cells. The odour is disagreeable; the taste, nauseous and bitter. In the parenchymatous tissue of both rhizome and petiole there are axially elongated intercellular cavities into which glandular hairs project, covered with a resinous secretion in which the active constituents are contained. The only likely substitutes for, or adulterants of, male fern rhizome are the rhizomes of Aspidium spinulosum and Athyrium Filix-foemina. The former very closely resembles male fern, but may be distinguished by the membranous scales, which bear on their margins glandular hairs; like male fern it is an active anthelmintic, this property depending partly at least upon the crystallisable body, aspidin, which it contains. The rhizome of A. Filix-foemina exhibits two large dumb-bell shaped steles in place of the seven or more present in male fern.
Constituents.—The chief constituent of male fern is a yellow amorphous substance of an acid nature, termed filmarone, to which the properties of male fern as a vermifuge are attributed. In solution it slowly decomposes into filicic acid and aspidinol, both of which also occur preformed in the drug. Filicic acid is crystalline and melts at 213° to 215°; aspidinol crystallises in white needles, melting at 143°, and is sparingly soluble in benzol and petroleum spirit. Other constituents of the drug are flavaspidic acid, which crystallises in long yellow prisms (melting-point, 154° to 155°), and albaspidin (melting-point, 148°); filicitannic acid is also present.
Action and Uses.—Male fern has an astringent action, and is occasionally used in the form of powder. Liquid extract of male fern is used to expel tape worm, to all varieties of which it is a direct poison (see Extractum Filicis Liquidum); in very large doses it is a violent irritant, giving rise to acute gastro-enteritis. Cases are on record in which considerable absorption has taken place and blindness has followed. Filicic acid is given in doses of 3 to 10 decigrams (5 to 15 grains), and has been recommended in place of liquid extract of male fern, but its action is less certain; filicin, the anhydride of filicic acid, is inactive.
Dose.—4 to 12 grammes (60 to 180 grains).
- Extractum Filicis Liquidum, B.P.—LIQUID EXTRACT OF MALE FERN.
- Exhaust male fern rhizome, in No. 20 powder, by percolation with ether, and remove the solvent from the clear percolate by distillation or evaporation on a water-bath, until the extract acquires an oily consistence. This extract is used entirely for the expulsion of tape worms and ankylostomata. Given a case of Taenia solium the best plan to adopt is to give from 4 to 6 drachms of magnesium sulphate late at night. A few hours after purgation, a dose of liquid extract (not less than 20 minims) should be given. About four hours later, this should be followed by a full dose of castor oil. The extract may be prescribed in gelatin capsules containing from 6 to 18 decimils (0.6 to 1.8 milliliters) (10 to 30 minims) in each. It may also be given in milk, but is more frequently dispensed as an emulsion. It can be emulsified with one-sixth its volume of tincture of senega, an equal weight of powdered gum acacia, or half its weight of compound powder of tragacanth. It may be prescribed as Mistura Filicis. Dose.—3 to 6 mils (45 to 90 minims).
- Mistura Filicis, B.P.C.—MALE FERN MIXTURE.
- Each fluid ounce contains about 1 fluid drachm of liquid extract of male fern, 1 drachm of powdered gum acacia, with a sufficient quantity of chloroform water. Dose.—15 to 30 mils (½ to 1 fluid ounce).
- Oleoresina Aspidii, U.S.P.—OLEORESIN OF ASPIDIUM.
- Aspidium, recently reduced to No. 40 powder, 100; acetone, a sufficient quantity. Average dose.—2 grammes (30 grains).