Microfluidic and hydrothermal preparation of vesicles using sorbitan monolaurate/polyoxyethylene (20) sorbitan monolaurate (Span 20/Tween 20)

Here, we present a method for preparing vesicles by combining hydrothermal emulsification with solvent diffusion (SD). The sorbitan monolaurate/polyoxyethylene (20) sorbitan monolaurate (Span 20/Tween 20) system was used as the target lipid because these lipids are cheap and advantageous for the production scale. The water-in-oil (W/O) emulsion stabilized with lipids was formed under hydrothermal conditions (240 °C under 10 MPa), followed by mixing with water that included lipids to obtain a W/O-in-water (W/O/W) emulsion. The SD for the W/O/W emulsion as a subsequent process yielded vesicles. The optimal preparation conditions were 50:50 wt% Span 20/Tween 20 as a mixing ratio (final lipid concentration 12 mM), octanoic acid as an organic solvent, 240 °C for 4 min during the hydrothermal treatment, and 4 °C for 24 h in the SD process. The diameter of the vesicles obtained was at most 100 nm, which was comparable to that of the W/O/W emulsion before SD. This suggested that the W/O/W emulsion acted as a template for vesicle formation. The number density, diameter, and membrane properties of vesicles depend on the mixing ratio of the water/oil/lipid system. Specifically, the number density of vesicles was low relative to that of vesicles prepared by the conventional method.

Hardly water-soluble drug-loaded gelatin nanoparticles sustaining a slow release: preparation by novel single-step O/W/O emulsion accompanying solvent diffusion

Paclitaxel (PTX)-loaded gelatin nanoparticles (NPs) were prepared, for the first time, by novel O/W/O emulsion with a single-step emulsion process accompanying solvent diffusion, in contrast to the conventional double-step emulsion processes. Linoleic acid was chosen among the natural fatty acids as the exterior medium for the single-step emulsion process accompanying solvent diffusion. The size mean and zeta potential of the PTX-loaded gelatin NPs in their suspension were 164.95 nm (±6.43 nm) distributed with a polydispersity of 0.074 (±0.046) and -23.85 mV (±12.66 mV), respectively. The size of the PTX-loaded gelatin NPs prepared in this study was the smallest among the reported sizes of PTX-loaded gelatin NPs, which would contribute to the enhanced permeability and retention (EPR). In addition, TEM showed that the loaded PTX was located mostly inside the gelatin NPs unlike previous investigations. Accordingly, the conceptual model of the designed PTX-loaded gelatin nanoparticle was introduced. Sustaining a slow PTX release on a day-time scale without an initial burst release into a release medium was observed along with a delay of more than 2 days (i.e., 50 h) before a bursting PTX release from 50 to 70 h despite the addition of a protein degrading enzyme. The observed PTX-loading efficiency was 54.5%. This loading efficiency was greater than that of previous study using gelatin of bloom 75-100 of Lu et al. to prepare PTX-loaded gelatin NPs using a desolvation method.

Development and statistical optimization of nefopam hydrochloride loaded nanospheres for neuropathic pain using Box-Behnken design

Nefopam hydrochloride (NFH) is a non-opioid centrally acting analgesic drug used to treat chronic condition such as neuropathic pain. In current research, sustained release nefopam hydrochloride loaded nanospheres (NFH-NS) were auspiciously synthesized using binary mixture of eudragit RL 100 and RS 100 with sorbitan monooleate as surfactant by quasi solvent diffusion technique and optimized by 35 Box-Behnken designs to evaluate the effects of process and formulation variables. Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetric (DSC) and X-ray diffraction (XRD) affirmed absence of drug-polymer incompatibility and confirmed formation of nanospheres. Desirability function scrutinized by design-expert software for optimized formulation was 0.920. Optimized batch of NFH-NS had mean particle size 328.36 nm ± 2.23, % entrapment efficiency (% EE) 84.97 ± 1.23, % process yield 83.60 ± 1.31 and % drug loading (% DL) 21.41 ± 0.89. Dynamic light scattering (DLS), zeta potential analysis and scanning electron microscopy (SEM) validated size, charge and shape of nanospheres, respectively. In-vitro drug release study revealed biphasic release pattern from optimized nanospheres. Korsmeyer Peppas found excellent kinetics model with release exponent less than 0.45. Chronic constricted injury (CCI) model of optimized NFH-NS in Wistar rats produced significant difference in neuropathic pain behavior (p < 0.05) as compared to free NFH over 10 h indicating sustained action. Long term and accelerated stability testing of optimized NFH-NS revealed degradation rate constant 1.695 × 10-4 and shelf-life 621 days at 25 ± 2 °C/60% ± 5% RH.