Distribution of amiodarone between lipid nanocapsules and residual micelles: Tangential flow filtration as a purification method and its impact on cytotoxicity

Abstract

Amiodarone (AMD) is an anti-arrhythmic drug prescribed for the treatment of atrial fibrillation. Despite its efficiency, AMD causes several extracardiac side effects due to its highly lipophilic nature, limiting its clinical use. Lipid nanocapsules (LNCs) are a promising approach for encapsulating AMD and altering its whole-body biodistribution. It has been established that during the phase inversion composition process to prepare LNCs loaded with AMD (LNC-AMD), some residual micelles will also be formed. These residual micelles could contain AMD and impact the formulation's cytotoxicity. In this study, we present a scalable tangential flow filtration (TFF) process for the separation of micelles from LNCs. Subsequently, dynamic light scattering and asymmetric flow-field flow fractionation in combination with UV and RI detections are subtly associated with a mass balance to assess the efficiency of TFF in removing free polyethylene glycol and surfactant micelles. An encapsulation efficiency of 91 % in the LNCs was calculated with a drug loading of 7.2 mg per gram of dry matter constituting the LNCs. Finally, the cytotoxicity of the LNC vector and LNC-AMD candidate nanomedicines, both purified and non-purified, was evaluated on H9C2, A549, and HepG2 cell lines. It has been demonstrated that the elimination of free polyethylene glycol and residual surfactant micelles results in a substantial enhancement in cell viability. The cytotoxic results raise questions about the cell-specific uptake and distribution of purified LNCs.

Keywords: Amiodarone; Cytotoxicity; Lipid nanocapsules; Micelles; Tangential flow filtration.