Dissolution of pure GLZ and all other prepared systems (i.e., complexes and PMs) were carried out in demineralized water.
Table III reports the values for the percent of drug dissolved within 20 min (DP
), mean dissolution time (MDT), and time to dissolve 50% of the drug (t
). The data show that the onset of dissolution of pure GLZ is slow (DP
value was 6.14%, and t
> 2 h).
Table III: Statistical comparison of dissolution profile of inclusion complexes.
Figure 6 shows dissolution profiles of pure GLZ, its PM, and inclusion complexes with HP–β–CD over a period of 120 min. The
dissolution rate of pure GLZ is low; 29.69% of the drug is dissolved in 120 min. Inclusion complexes of GLZ with HP–β–CD significantly
enhanced the dissolution rate of GLZ within 120 min, compared with PM and pure GLZ. PM with HP–β–CD also improved GLZ's rate
of dissolution. The highest improvement was obtained using a complex prepared through coevaporation.
Figure 6: Drug-release profile of glipizide–HP–β–CD complexes.
MDT is the first datum for the cumulative dissolution process that provides an accurate drug-release rate. A high MDT value
indicates great drug-retarding ability (18). The MDT of pure GLZ was high (99.64 min). This value decreased greatly after
the authors prepared GLZ's inclusion complexes and PM with HP–β–CD, which indicated an increase in dissolution rate. Coevaporation
2:1 had the lowest MDT (12.91 min).
Comparisons between the release profiles of different samples of GLZ were made with similarity factor f
. Table III shows that the release profiles of GLZ from all samples (i.e., complexes and PMs of HP–β–CD) and from pure GLZ
were dissimilar; f
values for these comparisons were less than 50. Coevaporation 2:1, which had a better in vitro dissolution profile, lower MDT, and lower f
values, was selected for further formulation of as an EOPT.