Administration of the Platycodon grandiflorum decoction 1g/kg PO to anesthetized dogs markedly increased mucous secretion in the respiratory tract; its potency resembled that of ammonium chloride. Likewise, a marked expectorant effect was demonstrated in anesthetized cats.

It was reported that Platycodon grandiflorum was a more potent expectorant than the root of Polygala tenuifolia but weaker than that of Polygala senega L. However, the result of the phenol red test in mice showed that platycodin was weaker than the root of Polygala tenuifolia. The oral doses of Platycodon grandiflorum irritated the pharyngeal and gastric mucosae, reflexedly increasing mucous secretion in the respiratory tract and diluting the sputum for easy expectoration. The crude preparation of Platycodon grandiflorum had an antitussive effect, its ED50 in guinea pigs was determined to be 6.4 mg/kg IP.

The aqueous or ethanol extract of P. grandiflorum at 200 mg/kg P0 lowered the blood glucose level of rabbits; the hypoglycemic curve of the aqueous extract was similar to that of tolbutamide 25-50 mg/kg PO. In rabbits with alloxan-induced diabetes, the aqueous or ethanol extract given at 500 mg/kg PO for 4 days also produced a hypoglycemic effect, simultaneous with restoration of the decreased liver glycogen level. The extracts also inhibited dietary hyperglycemia. In this respect, the ethanol extract was more potent than the aqueous extract.

The crude preparation of P. grandiflorum at a dose lower than one-fifth of the LD50 inhibited gastric secretion and prevented peptic ulcer in rats. The dose 100 mg/kg virtually inhibited gastric secretion induced by ligatien of the pylorus. Intraduodenal administration of the crude preparation of P. grandiflorum 25 mg/kg to rats prevented the formation of peptic ulcer; the strength of its action was equivalent to that of atropine 10 mg/kg SC. However, the prophylactic effect of the dose 100 mg/kg PO against the formation of stress ulcer was two times weaker than that of atropine 10 mg/kg SC. The crude preparation of P. grandiflorum markedly decreased the ulcer index in rats induced by acetic acid.

The crude preparation of P. grandiflorum was shown to have an antiinflammatory effect. The intragastric doses equivalent to one-tenth to one-fifth the LD50 antagonized carrageenin- and acetic acid-induced swelling of rat hind limbs. Oral administration of doses less than one-tenth of the LD50 once daily also markedly inhibited cotton pledget-induced granulation in rats. The drug was effective against adjuvant-induced arthritis in rats. It decreased the capillary permeability of mice with allergic reaction. Writhing and peritoneal exudation induced by intraperitoneal injection of P. grandiflorum in mice was inhibited by oral administration of the same agent. P. grandiflorum had no direct antibacterial effect, but its aqueous extract was shown to enhance the phagocytic function of macrophages, the bactericidal power of neutrophiles, and the lysozymal activity.

Intravenous injection of the crude preparation of P. grandiflorum to rats resulted in a transient fall in the blood pressure, bradycardia, and respiratory depression. High concentrations produced a negative inotropic effect on the isolated guinea pig auricle. Intra-arterial injection of 200-800 mg of the crude P. grandiflorum to anesthetized dogs reduced the vascular resistance of the coronary artery and hind limb vessels, thereby increasing the blood flow in these vasculatures, with a potency equal to that of papaverine. Likewise, injection of 4 mg/kg IV increased the blood flow in these vessels and simultaneously produced transient hypotension. Vasodilation was believed to be due to a direct action on the peripheral blood vessels.

The crude preparation of P. grandiflorum had sedative, analgesic, and antipyretic actions; it inhibited the spontaneous activity in mice and prolonged cyclobarbital sodium-induced sleep but did not prevent the development of convulsion caused by electric shock and pentylenetetrazole. The herb reduced hepatic cholesterol and increased the fecal excretion of sterols and cholic acid in rats. It also exhibited anticholinergic and antihistaminic actions by inhibiting ileal contraction in guinea pigs due to acetylcholine and histamine.

P. grandiflorum 2 g/kg PO produced anti-edema and diuretic effects in rats with congestive edema following bilateral ligation of the jugular vein. In vitro, the 1:10 herb decoction inhibited Epidermophyton floccosum.

The LD50 of the P. grandiflorum decoction in mice was determined to be 24 g/kg PO. P. grandiflorum had a very pronounced hemolytic effect; it had a hemolytic index of 1:10,000. Thus it cannot be administered by injection. The orally administered drug loses its hemolytic effect after being decomposed in the alimentary tract. Its MLD in mice was determined to be 770 mg/kg SC. The LD50 of the crude preparation of P. grandiflorum in mice and rats were 420 and >800 mg/kg PO, or 22.3 and 14.1 mg/kg IP, respectively.

Two cases of lung abscess were reported to have been effectively treated with Radix Platycodi White Powder (composed of P. grandiflorum , Fructus Crotonis, and Bulbus Fritillariae Cirrhosae). Radix Platycodi Decoction (composed of P. grandiflorum and Radix Glycyrrhizae) was also useful in lung abscess and lobar pneumonia. P. grandiflorum is often combined with other antitussives and expectorants in compound formulae and widely used in the treatment of common cold, cough, upper respiratory tract infection, bronchitis, and pneumonia.

The P. grandiflorum decoction can be administered orally to treat pharyngitis. The powder prepared from P. grandiflorum and the kernel of Lachryma-jobi may be used to treat dental caries and gingivitis.

P. grandiflorum -Rhizoma Pinelliae Decoction is used to treat postpartum gastric dysfunction. Radix Platycodi-Fructus Aurantti Decoction is useful in chest or upper abdominal fullness caused by exogenous cold pathogenic factor.

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