Herbs or shrubbery plants, with acrid, milky juice, alternate leaves, and scattered flowers, corolla 5-lobed. Fruit a one- to several-celled capsule. Many species of the tribe Lobeliae are acrid-narcotic poisons.
BOTANICAL CHARACTERISTICS.—Stems much branched from an annual root, pubescent; leaves ovate or oblong, gradually diminishing into leaf-like bracts. Capsule inferior.
RELATED SPECIES.—Lobelia syphilitica (great lobelia), Lobelia cardinalis (cardinal plant).
DESCRIPTION OF DRUG.—In the market the herb is broken up, but the fragments of green leaves, small pieces of the longitudinally ridged stem, the rather elongated, dried flowers, and the inflated, membranous capsules serve to identify it; odor irritating when inhaled; taste very pungent, persistently acrid, and tobacco-like.
Powder.—Characteristic elements: See Part iv, Chap. I, B.
CONSTITUENTS.—Lobeline (a poisonous, acrid, yellowish, aromatic liquid alkaloid), lobelic acid, lobelacrin (an active principle, probably lobelate of lobeline), inflatin (a tasteless, colorless, and odorless, probably inert, neutral principle), resin, fixed oil, gum, probably volatile oil, salts, etc.
Preparation of Lobeline.—Evaporate the acetic alcoholic tincture to syrup; triturate this with MgO in excess; agitate filtrate with ether. Evaporate ether and concentrate over sulphuric acid. It is quite volatile.
Preparation of Lobelacrin.—Obtain by concentrating tincture of lobelia in presence of animal charcoal; exhaust charcoal with boiling alcohol. It is the acrid principle, lobelate of lobeline. Ash, not more than 8 per cent.
ACTION AND USES.—Poisonous (— I, of course, disagree with Sayre here...there are probably 30 botanicals in this text more toxic than Lobelia, yet none of them are called "poisonous". This was a remnant of a then 70 year-old conflict between "regular school" medicine and the "irregulars" and is pure dialectic—Michael Moore); diaphoretic and expectorant; used in asthma, whooping-cough, and other spasmodic pulmonary affections. In large doses it is a cathartic and emetic, but, being a violent gastroirritant, it should not be used for these purposes on account of its danger. Dose: 1 to 15 gr. (0.065 to 1 Gm.). The latter dose as an emetic. The two species, syphilitica and cardinalis, are used medicinally, the former antisyphilitic and diaphoretic and the latter anthelmintic. Both were used by the Indians.
- OFFICIAL PREPARATIONS.
- Fluidextractum Lobeliae. Dose: 1 to 5 drops (0.065 to 0.3 mil).
- Tinctura Lobeliae (10 per cent.). Expectorant 15 drops (1 mil). Emetic 1 fl. dr. (4 mils).
A Manual of Organic Materia Medica and Pharmacognosy, 1917, was written by Lucius E. Sayre, B.S. Ph. M.