Effect of Labrasol on self-nanoemulsification efficiency of ramipril nanoemulsion.

The purpose of the present investigation was to evaluate the capacity of Labrasol as surfactant for self-nanoemulsification efficiency of ramipril nanoemulsion formulation. Based on the solubility profile of ramipril, Sefsol-218, Labrasol and Carbitol were selected as oil phase, surfactant and cosurfactant, respectively. Based on the stability profile of ramipril, standard buffer solution of pH 5.0 was selected as an aqueous phase for the development of ramipril nanoemulsion formulation. Nanoemulsion formulations of ramipril were developed using an aqueous phase titration method. Pseudoternary phase diagrams were constructed to identify the nanoemulsion region. Selected formulations were subjected to different thermodynamic stability tests using centrifugation, heating cooling cycles and freeze thaw cycles. The formulations which were stable at thermodynamic stability tests were taken for self-nanoemulsification efficiency test. No creaming, cracking, coalescence or phase inversion was observed on most of the formulations upon thermodynamic stability tests. All the formulations passed self-nanoemulsification tests in grade C, D and E but not in grade A and B. Because none of the formulation passed self-nanoemulsification efficiency test in grade A and B, it was concluded that Labrasol is not suitable as surfactant for oral or self nanoemulsifying drug delivery system of ramipril.