Liposomal formulations, as versatile nanocarrier systems suitable for targeted delivery, have a highly focused role in the therapy development of unmet clinical needs and diagnostic imaging techniques. Formulating nanomedicine with suitable zeta potential is an essential but challenging task. Formulations with a minimum ±30 mV zeta potential are considered stable. The charge of the phospholipid bilayer can be adjusted with membrane additives. The present Quality by Design-derived study aimed to optimise liposomal formulations prepared via the thin-film hydration technique by applying stearylamine (SA) or dicetyl phosphate (DCP) as charge imparting agents. This 3² fractional factorial design-based study determined phosphatidylcholine, cholesterol, and SA/DCP molar ratios for liposomes with characteristics meeting the formulation requirements. The polynomials describing the effects on the zeta potential were calculated. The optimal molar ratios of the lipids were given as 12.0:5.0:5.0 for the SA-PBS pH 5.6 (optimised sample containing stearylamine) and 8.5:4.5:6.5 for the DCP-PBS pH 5.6 (optimised sample containing dicetyl phosphate) particles hydrated with phosphate-buffered saline pH 5.6. The SA-PBS pH 5.6 liposomes had a vesicle size of 108 ± 15 nm, 0.20 ± 0.04 polydispersity index, and +30.1 ± 1.2 mV zeta potential, while these values were given as 88 ± 14 nm, 0.21 ± 0.02, and −36.7 ± 3.3 mV for the DCP-PBS pH 5.6 vesicles. The prepared liposomes acquired the requirements of the zeta potential for stable formulations.

The translation of nanomedicines from the lab level into marketed product faces several challenges, including characterization of physicochemical properties, pharmacodynamics, pharmacokinetics, process control, biocompatibility, and nanotoxicity, scaling-up as well as reproducibility. The challenges of nanomedicine development are in connection with the different requirements from the patient (clinical and therapeutic use), industry (production), and regulatory bodies (authorization process). This paper aims at reviewing the status and regulatory aspects of nano-based drug delivery systems with a focus on the Food and Drug Administration (FDA) and the European Medicine Agency (EMA) regulations. In addition to discussing the risks accompanied by the development of nanomedicine, the potential of following a risk-based methodology from the early stage of the R&D phase is emphasized here to ensure safety and efficacy when developing novel nano-based dosage forms. The R&D of nanomedicines is a complex and multidisciplinary approach, and there are still many challenges in their regulation and legislation. In general, the most critical considerations for nanomedicines are the product quality assessment (physicochemical characteristics, quality control, manufacturing process) and product safety assessment (pharmacokinetics, biodegradation, accumulation, and nanotoxicity). The paper presents a promising paradigm in the development and marketing authorization of nanomedicines, namely the Quality by Design (QbD) approach. Sufficient knowledge on the quality, safety, and efficacy of nanomedicines is necessary to obtain a significant focus on establishing robust, standardized methods for evaluating the critical quality attributes of nanomedicines. The QbD-based submission is highly recommended and required by the regulatory authorities, enabling a smooth clinical translation of the novel nanomedicines.