Pharmacologically, A. heteropoides has been known to possess antitussive, expectorant, antipyretic, antibacterial, analgesic and sedative effects which have been shown by research to result from the drug's asntihistaminic activity in inhibiting the release of anaphylactic mediator. To one of the effectual oils, elemicin, is attributed such antihistamine and antiserotonin effects. Asarum's antibacterial activity is attributable to its methyleugenol constituent.

The ethanol extract of A. heteropoides caused a brief decrease followed by a sustanined increase of 15-30 minutes in the perfusion volume of the isolated lung; isoproterenol did not show an initial lowering effect though it increased the perfusion volume of the lung, and the duration of its effect was the same as that of the extract. Thus the after effect of the herb is similar to the response elicited by isoproterenol. These actions served as the pharmacological basis for the traditional treatment of "cough with dyspnoea due to retention of phlegm".

The volatile oil of Asarum heterotropoides, produced stimulation at low dosage and inhibition at high dosage on the isolated frog heart, stopping the heart at the diastolic phase. The ethanol extract of A. heterotropoides had a marked stimulant effect on the isolated heart of rabbits: it promptly increased the cardiac contractility and heart rate for 7-10 minutes, suggesting the presence of positive inotropic and chronotropic effects. The agent increased the coronary flow in the isolated rabbit heart.

The hemodynamic activity of A.heterotropoides in anesthesized dogs was compared with that of higenamine and isoprenaline. Asarum extract had less heart rate increasing but more cardiac output stimulating effects than higenamine and isoprenaline.

Dl-Demethylcoclaurine (higenamine) has been shown to exert a wide variety of ?-adrenergic effects including cardiotonic, vasodilatory, smooth muscle relaxant, lipid-metabolism enhancing, and hyperglycemic effects.

From the insoluble fraction of the methanol extract of A. heterotropoides, four components -methyleugenol, kakuil, N-isobutyldodecatetramine, and higenamine-were found to markedly inhibit histamine-induced contraction of the isolated guinea pig ileum an antiallergic activity was demonstrated by the aqueous or ethanol extract of A.hetrotropoides which reduced by more than 40% the total amount of allergic mediators released in immediate hypersensitivity reaction.

In vitro studies proved that the ethanol extract and the volatile oil of A.heterotropoides inhibited gram-positive bacteria, Bacillus subtilis, and Salmonella typhi, and that the herb decoction was inhibitory against Mycobacterium tuberculosis and Salmonella typhi.

An antipyretic effects was achieved by intragastric administration of the volatile oil to rabbits with fever induced by exposure to heat, typhoid vaccine or tetrahydro-?-naphthylamine. The oil also lowered the body onload="highlight();" temperature of normal animals.

Four components of A. heterotropoides were found to markedly inhibit histamine induced contraction of the isolated guinea pig ileum. An anti allergic activity was demonstrated by the herb which reduced more than 40% the total amount of allergic mediators released in immediate hypersensitivity reaction.

When used for the treatment of diseases caused by allergic reactions, A. heterotropoides inhibits the release of mediators or functions to block cell rupture in antigen-antibody onload="highlight();" reactions.

Except those noted, all references come from Weng Weiliang, et al., Clinical Chinese materia medica, Henan Science & Technology Press, 1998