The data for each analysis are presented as mean ± standard deviation. Reproducibility was assessed by coefficient of variation. Mean concentrations of IR and LV in each solution were analyzed by least-squares linear regression to determine the percentage of the initial concentration remaining at each time point during the 24-h study period. Multiple linear regression and analysis of variance (SPSS for Windows, release 10.0.5, 1999) were used to determine whether container type (glass, PVC, or PAB) or concentration of IR or LV in the mixture at time 0 had any effect on rate of degradation of either drug. The commonly accepted cut-off for statistical significance of 5% was used for all analyses.

The concentration of IR or LV at any time point was considered within acceptable limits for degradation if the mean concentration had not declined below 90% of the final mixed concentration measured at time 0. A mixture was judged to be physically compatible if there was no visual change in the colour or clarity of the mixture, and no precipitate or other particulate formation was visually apparent. Viagra Super Active