Objective To verify the
absorption of
metronidazole through mouth cavity in vivo,and understand the absorption and excretion
of meltronidazole in vivo,and provide scientific bases for the safety assessment on oral health care products including
metronidazole Methods The determination of contents of metronidazole in blood by HPLC and pharmacokinetics analysis were carried out in SD rats at the 0 5 h,1 h,1,5 h,2 h,2 5 h,3 h and 4 5 h after the oral exposure to the toothpaste containing 8% metronidazole after the 30 minute ligation of esophagus with a dose of 1 mg/kg body weight (BW) respectively Results 6 88 μg/ml metronidazole was found in serum of SD rats at the 0 5 h after the oral exposure,which indicated that metronidazole in toothpaste could be absorbed through mucous membrane The fited drug concentration in serum time curve accorded with the one compartment model of first grade
absorption The treated parameters of pharmacokinetics were as follows,A=10 1449 μg/ml,Ke=0 4337 h,Ka=10 2571 h;Lag time=0 3770 h,t1/2(ka)=0 0676 h,t1/2(ke)=1 5984 h,T(peak)=0 3220 h,C(max)=8 4496 μg/ml,AUC=22 4043 μg/(ml·h),CL/F(S)=1 429 3 mg/(kg·h),V/F(C)=3 2936 mg/kg Conclusion Metronidazole could be absorbed through oral exposure Due to the genotoxicity of metronidazole,it was proposed that the application of metronidazole in oral health care products should be prohibited and limited,to avoid causing adverse health effects of long term exposure to it