Abstract

Background: Nimodipine is a highly lipophilic anti-hypertensive drug having 13% oral bioavailability (log P 3.41). Nimodipine is a prominent calcium channel blocker that must be given intravenously for an extended period of time (1-2 weeks) in order to treat cerebral vasospasm. It might be possible to substitute a sustained-release biodegradable formulation for the ongoing intravenous infusion used in this traditional therapy.

Objectives: The primary goal of this study was to formulate and evaluate the potentiality of ethosomes to deliver nimodipine, a potent water-insoluble anti-hypertensive drug, through the deeper layers of the skin. The greatest challenge for drug formulation is its poor oral bioavailability and solubility.

Methods: Nimodipine-loaded ethosomal gel was developed for transdermal drug delivery to increase solubility and skin penetration and to promote oral bioavailability. Central composite design employing a thin-film hydration method was used to prepare and optimize ethosomes. A better dispersion medium for nimodipine's preparation in ethosomes was selected based on the effect. The design consisted of independent variables as lipid (X1), ethanol (X2), and sonication time (X3). Concentrations were manipulated to examine the effects on three responses, namely the %entrapment efficiency (Y1), vesicle size (Y2), and %cumulative drug release (Y3). Surface morphology and other in vitro tests were used to identify ethosomes containing nimodipine. The preparation of ethosomal gel formulations began with incorporating a single ethosomal formulation (F4) into various concentrations of gelling agents. These studies performed physicochemical characterization, compatibility testing, and in vitro drug release tests on ethosomal gels. In vivo studies involving hypertensive rats were conducted after skin permeation, and ex vivo studies were performed. In order to assess the drug's permeability and deposition, we employed the abdomen skin of rats.

Results: The optimal process parameters resulted in ethosomes with 89.9 ± 0.19 percent entrapment efficiency, a vesicle size of 102.37 ± 5.84 nm, and a cumulative drug release of 98.3 ± 0.13%. pH and drug content measurements were consistent with the homogeneous ethosomal gels. Viscosity was found to increase with the spreadability. The ethosomal gel formulation (G2) met the regulatory standards regarding appearance, spreadability, viscosity, and in vitro release studies. Compared to pure nimodipine, ethosomal suspension (F4) and ethosomal gel (G2) formulations had higher ex vivo permeation, steady-state flux, and drug retention. Rats' mean arterial pressure (146.11 ± 0.84 mmHg) was significantly lower (p < 0.01) after after two hours of the experiment than it had been (p < 0.001) (98.88 ± 0.63 mmHg) after six hours.

Conclusion: To summarize, ethosomal gels have been found to be lipid carriers that enhance skin permeation and extend the anti-hypertensive effect of nimodipine. Compared to plain gel, ex vivo drug permeation through rat abdominal skin in ethosomal gel was enhanced. Gel-based ethosomal transdermal drug delivery formulations of nimodipine can be used to achieve a faster rate and extend the duration of drug delivery by more than 24 hours.