Formulation and Characterization of Nimodipine Nanoemulsion

Nimodipine is a dihydropyridine calcium channel blocker which is used in the treatment of hypertension. It is a highly lipophilic, poorly water soluble API. When we take nimodipine in oral dosage form, it shows bioavailability of only around 13% due to its extensive first-pass metabolism. Topical transdermal option of this potential API has been reported. Chemical penetration enhancers in many such products may cause skin irritation on prolonged therapy. As nanoemulsions do not need the chemical enhancers, they are advantageous over the conventional transdermal drug delivery systems. The aim of the present study was to develop nimodipine nanoemulsion formulation for topical administration. The nanoemulsion formulation consists of eucalyptus oil: tween 20/propanol-2 (1: 1, 1: 2, 1: 3, 3: 1, 2: 1) as an internal oil phase in external aqueous phase, Tween 80 as surfactant and propanol-2 as cosurfactant. Pseudoternary phase diagram was developed to determine the effect of the surfactant to cosurfactant mass ratio on the nanoemulsion formation, a transparent region. Optimized nanoemulsion was prepared by Sonication method and characterized by droplet size, SEM, viscosity and refractive index. In-vitro skin permeation of nimodipine through rat abdominal skin was determined by the Franz diffusion cell. Optimized nanoemulsion was also subjected to the thermodynamic stability studies. All the selected formulations were found to be stable. Novel nimodipine nanoemulsion formulation could be designed and projected to be suitable for transdermal application.