Systemic delivery of the anticancer agent arenobufagin using polymeric nanomicelles

Arenobufagin (ABG) is a major active component of toad venom, a traditional Chinese medicine used for cancer therapy. However, poor aqueous solubility limits its pharmacological studies in vivo due to administration difficulties. In this study, we aimed to develop a polymeric nanomicelle (PN) system to enhance the solubility of ABG for effective intravenous delivery. ABG-loaded PNs (ABG-PNs) were prepared with methoxy poly (ethylene glycol)-block-poly (d,l-lactic-co-glycolic acid) (mPEG-PLGA) using the solvent-diffusion technique. The obtained ABG-PNs were 105 nm in size with a small polydispersity index of 0.08. The entrapment efficiency and drug loading were 71.9% and 4.58%, respectively. Cellular uptake of ABG-PNs was controlled by specific clathrin-mediated endocytosis. In addition, ABG-PNs showed improved drug pharmacokinetics with an increased area under the curve value (a 1.73-fold increase) and a decreased elimination clearance (37.8% decrease). The nanomicelles showed increased drug concentrations in the liver and lung. In contrast, drug concentrations in both heart and brain were decreased. Moreover, the nanomicelles enhanced the anticancer effect of the pure drug probably via increased cellular uptake of drug molecules. In conclusion, the mPEG-PLGA-based nanomicelle system is a satisfactory carrier for the systemic delivery of ABG.

Nanoparticle-Laden Contact Lens for Controlled Ocular Delivery of Prednisolone: Formulation Optimization Using Statistical Experimental Design

Human eye is one of the most accessible organs in the body, nonetheless, its physiology and associated precorneal factors such as nasolacrimal drainage, blinking, tear film, tear turnover, and induced lacrimation has significantly decreased the residence time of any foreign substances including pharmaceutical dosage forms. Soft contact lenses are promising delivery devices that can sustain the drug release and prolong residence time by acting as a geometric barrier to drug diffusion to tear fluid. This study investigates experimental parameters such as composition of polymer mixtures, stabilizer and the amount of active pharmaceutical ingredient on the preparation of a polymeric drug delivery system for the topical ocular administration of Prednisolone. To achieve this goal, prednisolone-loaded poly (lactic-co-glycolic acid) (PLGA) nanoparticles were prepared by single emulsion solvent evaporation method. Prednisolone was quantified using a validated high performance liquid chromatography (HPLC) method. Nanoparticle size was mostly affected by the amount of co-polymer (PLGA) used whereas drug load was mostly affected by amount of prednisolone (API) used. Longer homogenization time along with higher amount of API yielded the smallest size nanoparticles. The nanoparticles prepared had an average particle size of 347.1 ± 11.9 nm with a polydispersity index of 0.081. The nanoparticles were then incorporated in the contact lens mixture before preparing them. Clear and transparent contact lenses were successfully prepared. When the nanoparticle (NP)-loaded contact lenses were compared with control contact lenses (unloaded NP contact lenses), a decrease in hydration by 2% (31.2% ± 1.25% hydration for the 0.2 g loaded NP contact lenses) and light transmission by 8% (unloaded NP contact lenses 94.5% NP 0.2 g incorporated contact lenses 86.23%). The wettability of the contact lenses remained within the desired value (<90 °C) even upon incorporation of the NP. NP alone and NP-loaded contact lenses both displayed a slow invitro drug release of drug over 24 h; where 42.3% and 10.8% prednisolone release were achieved, respectively. Contact lenses can be used as a medicated device to sustain ocular drug delivery and improve patient compliance; nonetheless, patients and healthcare professionals’ acceptability and perceptions of the new formulations entail further investigations.

Recent advancements in mechanical reduction methods: particulate systems

The screening of new active pharmaceutical ingredients (APIs) has become more streamlined and as a result the number of new drugs in the pipeline is steadily increasing. However, a major limiting factor of new API approval and market introduction is the low solubility associated with a large percentage of these new drugs. While many modification strategies have been studied to improve solubility such as salt formation and addition of cosolvents, most provide only marginal success and have severe disadvantages. One of the most successful methods to date is the mechanical reduction of drug particle size, inherently increasing the surface area of the particles and, as described by the Noyes-Whitney equation, the dissolution rate. Drug micronization has been the gold standard to achieve these improvements; however, the extremely low solubility of some new chemical entities is not significantly affected by size reduction in this range. A reduction in size to the nanometric scale is necessary. Bottom-up and top-down techniques are utilized to produce drug crystals in this size range; however, as discussed in this review, top-down approaches have provided greater enhancements in drug usability on the industrial scale. The six FDA approved products that all exploit top-down approaches confirm this. In this review, the advantages and disadvantages of both approaches will be discussed in addition to specific top-down techniques and the improvements they contribute to the pharmaceutical field.

Polylactide nanoparticles containing stably incorporated cyanine dyes for in vitro and in vivo imaging applications

Stably incorporating fluorescent molecules to polymeric nanoparticles (NPs) or micelles can facilitate the prolonged tracking of these drug-delivery vehicles in vitro and in vivo. However, incorporation of fluorescent molecules, usually charged and thereby water-soluble, through the encapsulation strategy to hydrophobic polymer matrices is challenging. The encapsulated fluorescent agents are also subject to rapid release when the polymeric NPs are exposed to biological media. To address this issue, we developed Cy5-conjugated polylactide (Cy5-PLA) NPs through Cy5/(BDI)ZnN(TMS)2 [(BDI) = 2-((2,6-diisopropylphenyl)amido)-4-((2,6-diisopropylphenyl)-imino)-2-pentene]-mediated ring-opening polymerization of lactide (LA) followed by nanoprecipitation. This process allows for covalent conjugation of Cy5 to PLA with quantitative incorporation efficiency and formulation of Cy5-PLA NPs with controlled particles size (approximately 100 nm). As much as 80% of Cy5 was still present in the Cy5-PLA NPs after theses NPs were incubated in PBS at 37 degrees C for 12 days. Cy5-PLA NPs were conjugated to the A10 RNA aptamer that binds to the prostate-specific membrane antigen (PSMA). The resulting Cy5-PLA/aptamer NPs were found to only bind to and get internalized by LNCaP and canine prostate adenocarcinoma cells (PSMA-positive), but not to PC3 cells (PSMA-negative). The Cy5-PLA NPs were administered to balb/c mice intravenously and found to have excellent signals with low-background fluorescence in various organs.