Pharmacodynamic Action And Toxicology Of Zhili San In China Veterinary Pharmacopoeia

"Zhili San" is one of the traditional Chinese patent medicines, which is collected in several versions of China Veterinary Pharmacopoeia. Composed of realgar, agastache rugosa and talc, it has an efficacy of heat-clearing, detoxifying, dissipating dampness and curing dysentery, which is used to cure white scour of piglets. As a kind of arsenic sulfide mineral drug, the principal drug realgar, mainly containing red arsenic sulfide(As2S2), has effects on detoxicating, anthelminthic, depriving the evil wetness, eliminating phlegm, restraining bacterium, and some stubborn diseases. Containing arsenic, a harmful element to animals, it may cause arsenic poisoning of ailing livestock due to uncertain dosage and excess time. To evaluate the prescription's clinical safety and validity from the perspective of modern pharmacology, we were commissioned by the Office of China Pharmacopoeia to make studies on the pharmacodynamic action and toxicology of Zhili San.In this experiment we examined the acute toxicity of Zhili San and realgar by intragastric administration in mice; assessed its long-term toxicity in rats through recording the amount of hydroposia and feeds-foraging per day and body weight per week, measuring hematologic and blood biochemical index after administration for 24 hours and withdrawal for 2 weeks, and making pathological section after intragastric administration for 4 weeks in rats with low (4 g/kg), middle (8 g/kg), and high (16 g/kg) dosage groups. Besides, we also carried out the in vitro bacteriostatic effect of Zhili San on E. coli, and its effects on propulsive ratio of mice's small intestine and protection against the experimental diarrhoea which is induced by sodium sulfate and castor oil, respectively. The results are as follows:Acute toxicity test: The medial lethal dose (LD50) of Zhili San by oral administration for mouse is 124.8 g/kg and its 95% confidence limits are 111.2 g/kg~142.5 g/kg, while, the medial lethal dose (LD50) of realgar by oral administration for mouse is 10.5 g/kg, and its 95% confidence limits are 9.7 g/kg ~ 11.1 g/kg. The LD50 of Zhili San is more than 39 times of its clinical dosage, indicating that its clinical use is safer. The LD50 of realgar in Zhili San is approximately 1.58 times of that of realgar, suggesting that Agastache rugosa and talc can reduce the toxicity of realgar in Zhili San.Long-term toxicity test: Rats in low dose group (4g/kg) did not appear visible toxicity. In middle dose group (8g/kg), rats showed significant toxicity, manifesting in reduced feed and water, body weight loss, gastrointestinal hyperemia and hemorrhage, presence of liver inflammatory cell infiltration, vacuolar degeneration of liver cells, hyporrhea of kidney and heart, as well as increased serum urea nitrogen, lutamate-pyruvate transaminase (GPT), glutamic-oxaloacetic transaminase (GOT) and alkaline phosphatase (ALP). While, rats in high dose group (16g/kg) did not die during the treatment. The above toxic reaction basically disappeared after withdrawal for 2 weeks, indicating that the toxicity is reversible. The feed and water intake of rats in low and middle dosage group reduced, suggesting that these dosage of Zhili San have certain side effects on animals'digestive function and water metabolism. The results of pathological test showed that the pathological changes induced by high doses of Zhili San were mainly in the digestive tract, liver and kidney. Gastrointestinal tract and liver damage caused digestive funcitional disturbance, therefore reducing the feed intake. The results of this test were in accordance with the reported disease characteristics of arsenic poisoning, but to a lesser extent, inferring that the toxic components of Zhili San should be the arsenic contained in realgar. The test of acute toxicity showed that the toxicity of realgar was restrainted with compatibility of Agastache rugosa and talc.In vitro bacteriostasis test: The antibacterial inhibition zone diameter of Realgar extract was 26.3 mm and that of Zhili San extract was 11.4 mm, while, both talc extract and Agastache rugosa extract appeared no significant inhibition. The minimal inhibitory concentration of realgar was 0.125 g/mL, while that of Zhili San was 0.5 g/mL. Both talc extract and Agastache rugosa extract had no significant antibacterial activity. The results showed that Zhili San has a certain inhibitory effect on E. coli and the realgar is the major antibacterial component.Effect of Zhili San on intestinal motility: Zhili San and realgar can promote the small bowel peristalsis, while, the effects of talc and agastache rugosa were not obvious compared with the control group, indicating that ZhiliSan extract could not inhibit the facilitation rate of small bowel, but significantly speed up the facilitation rate of small bowel which is mainly caused by realgar.Effect of Zhili San on experimental diarrhea: Zhili San and its single herb drugs are unable to inhibit the diarrhea caused by castor oil in mice, on the contrary, it can aggravate the diarrhea caused by sodium sulfate, in which talc plays a major role, manifesting that Zhili San has a certain promotion to the small bowel peristalsis and can help to promote the excretion of toxins to a certain extent. Zhili San and its single herb drugs can significantly inhibit diarrhea induced by castor oil in mice, indicating that it has a certain protective effect on the intestinal mucosa.In summary, Zhili San has a lower toxicity, and the medication is safe according to the dose defined by China Veterinary Pharmacopoeia. But with long-term use it can cause accumulation, resulting in damage of liver and kidney. Meanwhile, its toxicity is reversible. It has a certain inhibitory effect on E. coli, can promote small bowel peristalsis and inhibit the diarrhea induced by castor oil, but cannot reduce the diarrhea caused by sodium sulfate, indicating that it has a certain protective effect on the intestinal mucosa. The present study provides the reasonable guidance for clinical safe and rational administration of Zhili San through studies on its pharmacodynamic action and toxicology.