| The Antibacterial Activity and Pharmacokinetics of acidic, alkaline and long effect norfloxacin injections were studied. The inhibitory activity experiment against seven drug resistant S.aureus and eight other bacteria were carried out .It resulted that the activity of three norfloxacin injections against Streptococcus, Bacillus protus and Pseudomonas aeruginosa is relatively inferior (MIC is 4-8mg/L), Shigella flexneri and S.aureus were susceptible (MIC were 0.03-0.25mg/L), the effect of norfloxacin was better than Ciprofloxacin against Cl. Perfringers. The comparative study of three norfloxacin injections reveals that the inhibitory effect of alkaline norfloxacin was similar to that of long effect norfloxacin, the acidic norfloxacin was a little better than alkaline or long effect norfloxacin against Sereptococcus in vitro. There was no difference between the activity of norfloxacin against E.coli and Shigella flexneri. The inhibitory activity of Alkaline and long effect norfloxacin injections against Streptococcus, Salmonella, Bacillus protus and Pseudomonas aeruginosa were generally better than acidic norfloxacin. Compared with The standard stain (MIC 0.125-0.25mg/L), the results also indicated that the antibacterial activity of all of the three injections against drug resistant S.aureus were weak (>4000vg/ml). And against the two clinic isolated strains YLa and YLy, the MIC and MBC of acidic norfloxacin were more than 64mg/L, the alkaline and long effect norfloxacin were susceptible to drug resistant S.aureus than acidic norfloxacin, and they were susceptible to YL2 and YL7 than ciprofloxacin.The pharmacokinetics of three norfloxacin injections were compared in healthy swines. Norfloxacin was given to health swines at a dosage of 10mg/kg of body weight im and iv in a complete crossover study. Norfloxacin concentration in plasma was assayed by a high performance liquid chromatograph (HPLC) method using an UV detector and the limit of detection of norfloxacin in plasma was 50ng/ml. All the data was processed by MCPKP computer software and the pharmacokinetics parameters were calculated, based on two-compartment open model. The results revealed that the parameters of acidic norfloxacin after single im dose: the maximal concentration (Cmax) was 3.50234 +1.43539ug/ml ;the elimination half life (T1/2,beta) was 4.28715 + 3.39786h; the area under curve (AUC) was 14.031 + 3.859mg/l.h, the bioavailability (F) was 51.1%, of alkaline norfloxacin after single im dose :the maximal concentration (Cmax) was 2.63080 +0.68306ug/ml, the elimination half life (T1/2,beta) was 6.07517+3.04761h, the area under curve (AUC) was 12.499 + 2.423mg/l.h, the bioavailability (F) was 48.4%, of long effectnorfloxacin after single im dosing: the maximal concentration (Cmax) was 1.221397+0.05590ug/ml ;the elimination half life (Ti/2,beta) was 24.12160+ 7.75867h, the area under curve (AUC) was 19.655 + 2.373mg/l.h, the bioavailability (F) was 76.3%, of acidic norfloxacin after single iv dose: the Co was 13.84376 +8.85363ug/ml, the elimination half life (T1/2,beta) was 3.29670 +0.39538h, the area under curve (AUC) was 27.477 +2.007mg/l.h, of alkaline norfloxacin after single iv dose : the Co was 12.73648+5.18352ug/ml, the elimination half life (T1/2,beta) was 3.31289+0.48439h, the area under curve (AUC) was 25.747+3.149mg/l.h .The results suggest that the inhibitory effect of alkaline norfloxacin was identical to that of long effect norfloxacin hi vitro and was better than that of acidic norfloxacin used against resistant S.aureus obviously. After evaluating all the parameters, there was no significant difference found between acidic and alkaline norfloxacin after single iv dose. There were significant difference found among acidic, alkaline and long effect norfloxacin after single im dose after statistical analysis (P less than 0.05), especially, the elimination half life of long effect norfloxacin could prolong four to eight times, improved bioavailability approximation 30%. From the above result, long effect norfloxacin could im...
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