Objective      To compare the pharmacokinetic parameters and bioavailability of positive ion azithromycin niosomes and azithromycin solution in rats.       Methods      Drug concentrations in the plasma at different time points were determined by HPLC after single oral dose of small-particle-size azithromycin niosome (AMNSS)

large-particle-size azithromycin niosome (AMNSL) and azithromycin sol

ution (AM) in rats. The pharmacokinetic parameters were calculated by DAS 2.1.1. Statistical moment parameters were adopted to calculate the pharmacokinetic parameters including C

max

AUC

0-t

and t

max

. Analysis of nonparametric tests and two one-sided t-tests were used to evaluate the bioequivalence of the 3 formulations.       Results      The pharmacokinetic parameters of AMNSS

AMNSL and AM in plasma were: C

max

18.73

9.2 and 10.31 mg/L

respectively; t

max

6

4 and 2 h

respectively; AUC

0-t

371.79

160.41 and 136.09 mg·h/L

respectively; and AUC

0-∞

454.92

263.16 and 158.50 mg·h/L

respectively. AMNSS and AMNSL relative bioavailability F

0-t 

was 273.19% and 117.87%

respectively. The main pharmacokinetic parameters analyzed by variance

two side t-test and Wilcoxon rank sum test showed significant differences between AMNSS and AM

as well as AMNSS and AMNSL in vivo (

P

0.05)

but no significant difference between AMNSL and AM (

P

0.05).       Conclusion      AMNSL and AM are bioequivalent

while AMNSS and AM are not

neither are AMNSS and AMNSL.