Twelve rabbits were randomly divided into pH 7.4 and 4.7 group(n = 6)

different tetracaine solution with pH 7.4 or 4.7were sprayed onto the pharynx and larynx (5mg / kg wt)in rabbits. The blood samples were drawn from vein.The pharmacokinetics of tetracaine were measured by high performance liquid chromatography. The phamacokinetics pararneters of pll 7.4 and 4.7 groups were T

α 3.18 ± 13.64 and 1.29 ± 0.74 min; Cmaxi218.29± 175. 59 and 878.81 ± 347.29 ng/ml; Tpeaki2.52 ± 1.12 and 1.79 ± 0.40min;Vd;1360 ± 7.40 and 4.30 ± 2 .00ml/kg;Clsi302.56± 164.26 and 153.87 ± 84.22ng. ml-1/min

respectively

there were differences between pH 7.4 and 4.7 group (P<0.05 or P<0.01). In addition

the tetracaine solutions with above two pH values were injected into intestinal lumen of mice. The concentrations of tetracaine in intestinal muscle after 10 min also were measured. The results indicate that the distribution quantity of tetracaine solution of pH 7.4 or 4 .7 in intestinal muscle were 6.37 ±3.20 or 1.38±1.20 mg/g

respectivealy. There was significant difference (P<0.01) in concentrations between two pH solution of tetracaine. Experimental results showed that tetracaine solution with pH 7.4 was distributed into blood slowly with low blood concentration and rapid elimination rate.