Spontaneous In Situ Formation of Liposomes from Inert Porous Microparticles for Oral Drug Delivery

Focused ion beam-scanning electron microscopy provides novel insights of drug delivery phenomena

Scanning electron microscopy (SEM) has long been a standard tool for morphological analyses, providing sub micrometer resolution of pharmaceutical formulations. However, analysis of internal morphologies of such formulations can often be biased due to the introduction of artifacts that originate from sample preparation. A recent advancement in SEM, is the focused ion beam scanning electron microscopy (FIB-SEM). This technique uses a focused ion beam (FIB) to remove material with nanometer precision, to provide virtually sample-independent access to sub-surface structures. The FIB can be combined with SEM imaging capabilities within the same instrumentation. As a powerful analytical tool, electron microscopy and FIB-milling are performed sequentially to produce high-resolution 3D models of structural peculiarities of diverse drug delivery systems or their behavior in a biological environment, i.e. intracellular or -tissue distribution. This review paper briefly describes the technical background of the method, outlines a wide array of potential uses within the drug delivery field, and focuses on intracellular transport where high-resolution images are an essential tool for mechanistical insights.

Hydrogenated phospholipid, a promising excipient in amorphous solid dispersions of fenofibrate for oral delivery: Preparation and in-vitro biopharmaceutical characterization

Amorphous solid dispersions (ASD) represent a viable formulation strategy to improve dissolution and bioavailability of poorly soluble drugs. Our study aimed to evaluate the feasibility and potential role of hydrogenated phospholipid (HPL) as a matrix material and solubilizing additive for binary (alone) or ternary (in combination with polymers) solid dispersions, using fenofibrate (FEN) as the model drug. FEN, incorporated within ASDs by melting or freeze-drying (up to 20% m/m), stayed amorphous during short-term stability studies. The solubility enhancing potential of HPL depended on the dissolution medium. In terms of enhancing in vitro permeation, solid dispersions with HPL were found equally or slightly more potent as compared to the polymer-based ASD. For studied ASD, in vitro permeation was found substantially enhanced as compared to a suspension of crystalline FEN and at least equal compared to marketed formulations under comparable conditions (literature data). Additionally, while the permeation of neat FEN and FEN in binary solid dispersions was affected by the dissolution medium (i.e., the "prandial state"), for ternary solid dispersions the permeation was independent of the "prandial state" (FaSSIF = FeSSIF). This suggests that ternary solid dispersions containing both polymer and HPL may represent a viable formulation strategy to mitigate fenofibrate's food effect.

The processes behind drug loading and release in porous drug delivery systems

Porous materials are ubiquitous and exhibit properties suitable for depositing therapeutic compounds. Drug loading in porous materials can protect the drug, control its release rate, and improve its solubility. However, to achieve such outcomes from porous delivery systems, effective incorporation of the drug in the internal porosity of the carrier must be guaranteed. Mechanistic knowledge of the factors influencing drug loading and release from porous carriers allows rational design of formulations by selecting a suitable carrier for each application. Much of this knowledge exists in research areas other than drug delivery. Thus, a comprehensive overview of this topic from the drug delivery aspect is warranted. This review aims to identify the loading processes and carrier characteristics influencing the drug delivery outcome with porous materials. Additionally, the kinetics of drug release from porous materials are elucidated, and the common approaches to mathematical modeling of these processes are outlined.

Preparation and physicochemical characterization of N-succinyl chitosan-coated liposomes for oral delivery of grape seed extract and evaluation of its effect on pulmonary fibrosis induced by bleomycin in rats

Objectives

This study aimed to develop an oral succinyl chitosan-coated liposomal formulation containing grape seed extract and assess its therapeutic efficacy in rats with bleomycin-induced pulmonary fibrosis.

Materials and Methods

N-succinyl chitosan was synthesized, and the liposomal formulations were prepared and characterized regarding phenolic content assay and morphology. Size, zeta potential, in vitro drug release, and stability. Pulmonary fibrosis was induced by intratracheal bleomycin injection, and hydroxyproline measurements, lung weight, animal body weight, as well as histopathological studies were performed.

Results

Succinyl chitosan increases the physical stability of the formulation, especially in acidic conditions. Drug release studies revealed that 66.27% of the loaded drug was released from CF2 in an acidic medium in 2 hr, but 92.31% of the drug was released in 8 hr in a pH=7 medium. An in vivo study demonstrated that rats exposed to bleomycin significantly lost weight, while those treated with CF2 (400 mg/kg) partially regained weight. Bleomycin treatment increased the mean lung weight and the amount of hydroxyproline in the lungs; these values were significantly decreased in the group treated with 400 mg/kg CF2 (P<0.05). Histopathological examination confirmed that treatment with 400 mg/kg CF2 improved lung fibrosis.

Conclusion

In rats, oral administration of N-succinyl chitosan-coated liposomes containing grape seed extract at the 400 mg/kg dose ameliorates bleomycin-induced pulmonary fibrosis.

Carboxymethyl chitosan coated medium-chain fatty acid nanoliposomes: structure, composition, stability and in vitro release investigation

Medium-chain fatty acids (MCFAs) have been proven as an easy energy source and active ingredient to prevent obesity and other metabolic disorders. However, the inherent hydrophobic nature of MCFAs causes poor aqueous solubility and dissolution in the gastrointestinal (GI) tract, thus limiting their applications in aqueous foods. To address these issues, a nutraceutical carrier system was developed by coating nanoliposomes with carboxymethyl chitosan (CMCS) through a series of well-designed processes, including thin-film hydration, dynamic high pressure microfluidization (DHPM) and surface modification. Electron microscopy investigation reveals an obvious morphology evolution from the uncoated nanoliposomes (UC-LPs) to the final CMCS coated nanoliposomes (CMCS-LPs). Together with the FTIR results, it confirms the successful coating of CMCS. More importantly, the resultant CMCS-LPs have a more negatively charged surface with a ζ-potential value of around -18.5 mV, which helps to increase the stability by avoiding severe particle aggregation. Owing to the above benefits, the encapsulated MCFAs can be safely retained in a long storage period of 90 days at 4 °C and the new carrier system also exhibits a more sustained release of MCFAs in the GI fluid.