In vitro and ex vivo Studies of Nonionic Surfactant Vesicles Using 23 Factorial Design: Metoprolol Tartrate Used as Model Drug

The purpose of this study was to formulate and investigate metoprolol tartrate (MT) loaded non-ionic
surfactant vesicles using 23 factorial designs. Preparation of niosomal drug delivery of MT increased
its bioavailability which led to being better therapeutic effects, reduced the frequency of dosing and
decreased side effects of hypertensive patients. Ether injection method (EIM) and thin film hydration
method (TFHM) were used for the preparation of all formulations as per full factorial design to study
the effect of two independent variables X1 (amount of span-60), and X2 (amount of cholesterol) on
three dependent variable Y1 (percent drug entrapment efficiency), Y2 (percent drug content) and Y3
(percent cumulative drug release) respectively. The relation between the dependent and independent
variables was drawn out from the mathematical equation and response surface methodology (RSM).
Statistical analysis was performed using ANOVA. Microscopic observation confirmed that all particles
were uniform in size and shape. The particle size of niosomes measured by SEM was between 3 μm
to 4.5 μm that given the evidence of large uni-lamellar vesicles formed by EIM and TFHM. The
percent drug entrapment efficiency was found to be highest for formulations MTEIM-8 and MTTFHM-8
with values 97.11% and 95.56% respectively. In vitro dissolution studies were carried out in
phosphate buffer (pH 6.8) for 8 hours at 100 rpm and maintained at 37 ± 0.5°C according to USP-II
paddle method and absorbance was taken at 226 nm. The probable drug release mechanism may be
fickian (class I) diffusion as the correlation coefficient (R2) best fitted with zero order and release
exponent (n) was less than 0.43. The FTIR studies have been done to confirm no interaction along
with drug and polymer. In vitro and ex vivo comparative studies showed that non-ionic surfactant
vesicle had controlled the release of drug for a longer period. Finally, it can be concluded that nonionic
surfactant vesicle could be an effective for delivery of MT with increased bioavailability.