The dried flowering herb of Lobelia inflata. North America, B.P. The leaves and tops of Lobelia inflata collected after a portion of the capsules have become inflated, U.S.P.

Characters. - Usually in compressed oblong rectangular packages, weighing from half a pound to a pound each, and wrapped in sealed and labelled papers. The separate pieces are of varying lengths, yellowish-green, angular, and bearing sessile or stalked hairy oval irregularly toothed leaves, together with some flowers and fruits. Odour somewhat irritating; taste at first mild, but, after chewing, burning and acrid.

Composition. - Lobelina, a yellowish liquid with alkaline reaction, soluble in water, spirit, and ether, and possessing the poisonous properties of the drug; also an acrid principle, lobel-acrin, yielding lobelic acid; resins and a volatile oil are obtained in minute quantities.

Preparations.

B.P.

Dose.

Tinctura Lobeliae (2 1/2 oz. in 1 pint spirit)..................................................

10 min. to 1/2 fl. dr.

„ ,, aetherea (2 1/2 oz. in 1 pint spirit of ether)..

10 min. to 1/2 fl. dr. or more.

U.S.P.

Acetum Lobeliae (in dilute acetic acid 10 per cent.) ......................................

1/2-1 fl. dr.

Extractum Lobeliae Fluidum ........................................................................

1-5 gr.

Tinctura Lobeliae (20 per cent.)....................................................................

1/2-2 fl. dr.

Physiological Action. - Taken internally it causes a feeling of burning in the oesophagus, stomach, and intestines; vomiting, headache, giddiness, and great prostration; sometimes followed by convulsions and coma. Hence its action is very like that of tobacco, only differing in the greater intensity of the local burning sensations. It is often used to excess by the Cofnnites, whose theory is 'Heat is life,' and most cases of poisoning by it are due to its employment by such herbalists. It produces death by paralysis of the respiratory centre. Small doses first raise and then depress the blood-pressure; large doses paralyse the vaso-motor centre and the peripheral ends of the vagi (Att-wood).

Uses. - It is chiefly used as a remedy in spasmodic asthma and other affections of air-passages accompanied by dyspnoea -e.g. chronic bronchitis with a tendency to spasm of the bronchial muscles. Ringer states that larger doses must be used than those given in most text-books; he recommends 10 min. every ten minutes while the fit is on. In a case of poisoning, evacuate the stomach; give demulcents and stimulants.