Formulation by design of felodipine loaded liquid and solid self nanoemulsifying drug delivery systems using Box–Behnken design

Objective: To design and develop liquid and solid self-nanoemulsifying drug delivery systems (SNEDDS and S-SNEDDS) of felodipine (FLD) using Box–Behnken design (BBD).

Methods: Solubility study was carried out in various vehicles. Ternary phase diagram was constructed to delineate the boundaries of the nanoemulsion domain. The content of formulation variables, X1 (Acconon E), X2 (Cremophor EL) and X3 (Lutrol E300) were optimized by assessment of 15 formulations (as per BBD) for mean globule sizes in Millipore water (Y1), 0.1?N?HCl (Y2), phosphate buffer (pH 6.4) (Y3); emulsification time (Y4) and T_85% (Y5). The responses (Y1–Y5) were evaluated statistically by analysis of variance and response surface plots to obtain optimum points. The optimized formulations were solidified by adsorption to solid carrier technique using Aerosil 200 (AER).

Results and discussion: Transmission electron microscopy images confirmed the spherical shape of globules with the size range concordant with the globule size analysis by dynamic light scattering technique (<60?nm). The surface morphology of S-SNEDDS (before release) by scanning electron microscopy and atomic force microscopy indicated that SNEDDS are adsorbed uniformly on the surface of AER. The dried residue of S-SNEDDS (after release) revealed the presence of nanometric pores vacated by the previously adsorbed SNEDDS onto AER. Differential scanning calorimetry and X-ray powder diffraction studies illustrated the change of FLD from crystalline to amorphous state.

Conclusion: This study indicates that owing to nanosize, SNEDDS and S-SNEDDS of FLD have potential to enhance its absorption and may serve an efficient oral delivery.