COMPARISON OF CONCENTRATION OF PIROXICAM IN BLOOD AND LOCAL SITE AFTER TWO ROUTES OF ADMINISTRATION

The systematic and local concentrations of piroxicam after oral and transdermaladministration were determined and compared. Mice were randomly grouped,and oral suspensions(0.72 mg· ml^-1) or transdermal gels 1 mg· ml^-1 were given,Systematic concentration (C_s)andlocal concentration(C₁) of the drug in each mouse were determined by HPLC method, Aftertranedermal administration of 0.25 mg of piroxicam gels C_max(s)=8.06μg· ml-1 and AUC^0～24_(s)=58.36μg·h·ml^-1 were obtained, whereas after oral administration of 0.026 mg·10g^-1 bodyweight of piroxicam suspensions C_max(s) was 36.82 μg· ml^-1 and AU^0～24_(s)was 155.59μg·h·ml^-1 . The C₁/C_s ratio(0. 01) through oral route was far lower than the C₁/C_s ratio (0.13)through transdermal route, The area under local concentration—time curve(15. 85μg·h·ml^-1)calculated from transdermal administration was much higher than that from oral administration (1.93μg·h·ml^-1).So,it seems to be unreasonable that only serum concentration is taken as a criterion forbioavailability test of piroxicam for local dosage forms,the local drug concentration should also beinvestigated and evaluated.