Nanoemulsion as Carrier for Stability Enhancement of Ramipril

Abstract

Ramipril is a very sensitive and unstable antihypertensive drug molecule. Marketed formulations of ramipril lead to decrease in its assay value due to mechanical stress, compression, manufacturing processes, excipients, storage conditions, heat, moisture, and alkaline pH. Therefore the purpose of the present study was to enhance its stability using nanoemulsion technique. In order to enhance its stability, pH degradation studies at room temperature were performed using different standard buffer solutions as an aqueous phase in the nanoemulsion formulation. Nanoemulsion formulation was prepared by aqueous phase titration method. Shelf life of nanoemulsion was determined using Arrhenius plot. The degradation of ramipril after 180 days of storage was significantly lowest in formulation of pH 5.0 as compared to other formulations. The shelf life of nanoemulsion formulation was found to be highest at refrigerator temperature (2.87 years). These results indicated that stability of ramipril can be enhanced in nanoemulsion formulation using standard buffer (pH 5.0) as an aqueous phase.

Keywords:

• Nanoemulsion
• ramipril
• Sefsol 218
• stability
• Tween 80

The authors are thankful to Ranbaxy Research Laboratory, India and Nikko Chemicals, Japan for providing the gift sample of ramipril base and Sefsol 218, respectively.

Notes

^a Degradation constant (k) from slopes of the first-order degradation kinetic plot.

^a Temperature in degree Kelvin.

^b Degradation constant (k) from slopes of the first-order degradation kinetic plots.

^c Shelf life of nanoemulsion formulations.