Objective: To explore the dose-effect relationship of Maxin Shigan decoction with dosage changes of Gypsum Fibrosum. Method: Based on the original dose of Maxing Shigan decoction

the dose of Ephedrae Herba

Armeniacae Semen Amarum and Glycyrrhizae Radix et Rhizoma Praeparata cum Melle was unchanged

dosage of gypsum was changed

in another Maxing Shigan decoction there was no Gypsum. The male Sprague-Dawley rats were randomly divided in to 13 groups

including Maxing Shigan decoction dose 1-dose 10

positive drug group

normal group and model group. Fever model was induced by injecting lippolysaccharide (LPS) through the tail vein.The temperatures was recorded

and TRI was calculate;concentration of prostaglandin E2(PGE2) in the plasma was detected;Graphpad prism 5.0 software was used to dose-effect analysis. Result: Both the Maxing Shigan decoction with change of dosage of Gypsum Fibrosum and the decoction with no Gypsum could reduce body temperature in fever rats

and reduce the plasma PGE2 levels. Compared to the decoction without Gypsum Fibrosum

the groups with Gypsum Fibrosum significantly decrease body temperature

PGE2 levels and temperature reaction index(P<0.05

P<0.01). Concentration for 50% of maximum effect(EC50) was 2.785 g· kg-1;Therapeutic window for [D]20-[D]80 was 2.218 to 3.497 g· kg-1. Conclusion: Decoction without Gypsum Fibrosum has weak antipyretic effect

which may be related to the effect of Glycyrrhizin

Amygdalin and Ephedrae Herba. Decoction with Gypsum Fibrasum enhanced rapidly antipyretic effect

and with a small dosage range the effect showed a obvious change.