Developing a rapid analytical method for simultaneous determination of apigenin and gallic acid: validation and application in a nanoliposomal formulation.

OBJECTIVE: Apigenin and gallic acid are natural compounds that are useful as antioxidant, anti-inflammatory and anticancer agents, especially when used together in combination. Therefore, the development and validation of a simultaneous method of analysis for both compounds in pure form and when encapsulated in an advanced delivery system such as liposomes would be useful. METHODS: Analysis was performed using C18 column under isocratic conditions. The mobile phase was acetonitrile: water containing 0.2% orthophosphoric acid at a ratio of 67:33, flow rate 1 ml/min, and detection wavelength 334 nm for apigenin and 271 nm for gallic acid. RESULTS: The assay method was linear at the concentration range (5-600 µg/mL) with R2 of 1 for both drugs. The method was also shown to be precise and robust with RSD less than 2% with LOD (0.12, 0.1 µg/mL) and LOQ (4.14, 3.58 µg/mL) for apigenin and gallic acid respectively. The method was also applicable for the determination of the entrapment efficiency of both drugs when co-loaded in a nanoliposomal formulation. CONCLUSION: The described HPLC method was shown to be suitable, sensitive, and reproducible for the simultaneous identification and quantification of apigenin and gallic acid. The analytical results were accurate and precise, with good recovery, low limit of detection, and the chromatographic assay was accomplished in less than 3 min, suggesting the suitability of the method for routine analysis of both drugs in pharmaceutical formulations.

Explosomes: A new modality for DEB-TACE local delivery of sorafenib: In vivo proof of sustained release.

The current medical practice in treating Hepatocellular carcinoma (HCC) using Drug Eluting Transarterial chemoembolization (DEB-TACE) technique is limited only to hydrophilic ionizable drugs, that can be attached ionically to the oppositely charged beads. This limitation has forced physicians to subscribe the more hydrophobic, first treatment option drugs, like sorafenib systemically via the oral route, thus flooding the patient system with a very powerful, non-specific, multiple-receptor tyrosine kinase inhibitor that is associated with notorious side effects. In this paper, a new modality is introduced, where highly charged, drug loaded liposomes are added to oppositely charged DEBs in a manner causing them to "explode" and the drug is eventually attached to the beads in the lipid patches covering their surfaces; therefore we call them "Explosomes". After fully describing the preparation process and in vitro characterization, this manuscript delves into an in vivo pharmacokinetic study over 50 New Zealand rabbits, where explosomal loading is challenged vs oral as well as current practice of emulsifying sorafenib in lipiodol. Over 14 days of follow up, and compared to other groups, explosomal loading of SRF on embolic beads proved to cause a slower release pattern with longer Tmax, lower Cmax and less washout to general circulation in healthy animals. This treatment modality opens a new untapped door for local sustained delivery of hydrophobic drugs in catheterized organs.

Nanostructured lipid carriers incorporating prickly pear seed oil for the encapsulation of vitamin A.

BACKGROUND: Solid lipid nanoparticles (SLNs) are dispersions synthesized by replacing liquid lipid in an o/w emulsion with solid lipids. Nanostructured lipid carriers (NLCs) improve on some of the major limitations of the SLNs as NLCs use liquid lipids along with crystalline solid fatty acids to build the core. AIMS: This work aims to investigate the potential advantage of using Prickly Pear (PP) seed oil to develop NLCs for topical delivery of vitamin A. METHODS: Four PP-based NLC formulations with varying composition have been developed using the hot homogenization method and compared with a SLN formulation that is free of PP oil. The effect of this variation on entrapment efficiency, in vitro release behavior, and ex vivo permeation, was investigated. Additionally, particle size and polydispersity index (PDI) upon storage, zeta potential, and thermal behavior were characterized. RESULTS: PP-based NLCs exhibited smaller particle size in the range of 215-244 nm, and PDI <0.3. In contrast, SLN having no PP oil had a larger diameter of 365 nm, with heterogeneous distribution (0.92 PDI). In assessing the in vitro release, an inverse relationship was observed between the diffusion flux and the entrapment efficiency. The changes in the constituting matrix of the NLCs lead to a significant potential variation in their properties, and hence allowing it to be tailored for specific usages. CONCLUSIONS: In all cases, NLCs formulations have shown superior attributes to the SLN carriers. This was linked in most cases to the presence of PP oil, supporting the value of utilizing PP oil in cosmeceutical applications.

Sustained protein release from hydrogel microparticles using layer-by-layer (LbL) technology.

CONTEXT AND OBJECTIVES: Since most of developed therapeutic proteins are intended to treat chronic diseases, patients are prescribed multiple injections for long time periods, and therefore, sustained release formulations are much needed. However, challenges facing these formulations are quite significant. In this context, a model protein, lysozyme (Lys), was loaded on hydrogel microparticles (beads) and the ability of layer-by-layer (LbL) coating to control Lys release and maintain its activity over a one-month period was investigated. METHODS: LbL coating was composed of chondroitin sulfate as a negatively charged polyelectrolyte and a biocompatible, hydrolytically degradable poly ß-aminoester as a positively charged polyelectrolyte. Loading distribution was monitored by fluorescence imaging, and followed by depositing a series of LbL coatings of different thicknesses. Release of Lys from these formulations was studied and activity of released fraction was determined. RESULTS: Lys was loaded effectively on hydrogel beads achieving about 9 mg protein/100 mg wet spheres. LbL coating was proven successful by monitoring the zeta potential of the beads, which was reversed after the addition of each layer. In vitro release studies showed sustained release profiles that depend on the thickness of the deposited coat, with t50 extended from 4.9 to 143.9 h. More importantly, released Lys possessed a high degree of biological activity during the course of release maintaining at least 72% of initial activity. CONCLUSIONS: Successful loading of Lys and extension of its release while maintaining a considerable degree of activity might make this formulation suitable for use with other active therapeutic proteins.

Novel Layer-by-Layer Deposition Technique for the Preparation of Double-Chambered Nanoparticle Formulations.

In this work, we report a novel method of layer-by-layer (LbL) deposition using concentration tubes that enables faster process and less damage to fragile nanocores than previously described methods. Such methods are generally based on continuous cycles of centrifugation/resuspension for long times and at high speeds, which may eventually lead to the aggregation of the deflocculated suspension of nanoparticles into a compact, non-resuspendable cake. The new method was applied to the preparation of a double-chambered nanocarrier system, which was successfully loaded with a fluorescently labeled model protein (lysozyme) and a model small molecule (fluorescein) in two defined and separate compartments, namely the poly lactide-co-glycolide (PLGA) core (∼110 nm) and an outer shell obtained by LbL surface coating. The new method yielded stable suspensions of drug-loaded, LbL-coated PLGA nanoparticles, while centrifugation at high speeds and long time intervals leads to a compact cake of non-resuspendable aggregates. These nanocarriers were taken up by MDCK cells in vitro, where a colocalization of both model compounds was shown by confocal imaging.

Encapsulation of enzymes in Layer-by-Layer (LbL) structures: latest advances and applications.

Layer-by-Layer (LbL) technology has become an active area of research and is currently considered a hot topic with many potential applications, especially in the pharmaceutical and biopharmaceutical fields. This review is providing an overview of current approaches and applications of LbL designs used to immobilize and/or encapsulate various enzymes. One aim was to show the versatility and the potential of this technique in obtaining different designs and architectures fulfilling a wide range of needs and applications. Another important aim was to shed light on the techniques commonly used to characterize LbL structures and to monitor the process of layer deposition. Special attention was given to LbL structures encapsulating multiple enzymes where the function depends on the sequential activities of encapsulated enzymes.