Contrastive Studies of Cytarabine/Daunorubicin Dual-Loaded Liposomes Prepared by pH Gradient and Cu2+ Gradient Method

Research on the preparation process of the cytarabine/daunorubicin dual-encapsulation liposome and its physicochemical properties and performances in vitro/vivo

As the only Food and Drug Administration (FDA)-approved dual-encapsulation liposome injection for treating Acute myeloid leukemia (AML), CPX-351 outperforms the standard chemotherapy treatment "DA 7 + 3″ in terms of clinical effectiveness. Although research on dual-loaded liposomes has increased in recent years, little attention has been paid to their preparation, which can affect their quality, efficacy, and safety. This study explored various preparation processes to create the cytarabine/daunorubicin co-loaded liposome (the Cyt/Daun liposome) and eventually settled on two methods: the sequential loading approach, thin film hydration-extrusion-copper ion gradient, and the simultaneous encapsulation technique, copper ion gradient-concentration gradient. Different preparation methods resulted in different particle sizes and encapsulation efficiencies; the two aforementioned preparation processes generated dual-loaded liposomes with comparable physicochemical properties. The sequential encapsulation technique was selected for the subsequent research owing to its higher encapsulation efficiency prior to purification; the prepared Cyt/Daun liposomes had small and uniform particle size (108.6 ± 1.02 nm, Polydispersity index (PDI) 0.139 ± 0.01), negative charge (-(60.2 ± 1.15) mV), high drug encapsulation efficiency (Cyt 88.2 ± 0.24 %, Duan 94.2 ± 0.45 %) and good plasma stability. To improve its storage stability, the Cyt/Daun liposome was lyophilized (-40 °C for 4 h, maintained for 130 min, and dried for 1200 min) using sucrose-raffinose (mass ratio 7:3; glycolipid ratio 4:1, w/w) as a lyoprotectant. The lyophilized liposomes were purple cakes, redissolved rapidly with insignificant alterations in particle size and encapsulation efficiency, and possessed well storage stability. The pharmacokinetic and tissue distribution studies demonstrated that the Cyt/Daun liposome could achieve long circulation and maintain synergic proportions of drugs within 24 h, increasing the accumulation of drugs at tumor sites. Furthermore, the in vitro/in vivo pharmacodynamic studies confirmed its good anti-tumor activity and safety.

The first nano-cocrystal formulation of marine drug cytarabine with uracil based on cocrystal nanonization strategy for long-acting injection exhibiting enhanced antitumor activity

To emphasize the superiority of uracil (UR) in ameliorating biopharmaceutical characteristics of marine antitumor medicine cytarabine (ARA), thus gaining some innovative opinions for the exploitation of nanococrystal formulation, a cocrystal nanonization strategy is proposed by integrating cocrystallization and nanosize preparation techniques. For one thing, based on UR's unique structural features and natures together with advantages of preferential uptake by tumor cells, cocrystallizing ARA with UR is expected to improve the in vitro/vivo performances. For another, the nanonization procedure is oriented towards maintaining the long-term effective drug level. Along this route, a cocrystal of ARA with UR, viz., ARA-UR, is successfully synthesized and then transformed into nano-cocrystal. The cocrystal structure is precisely confirmed by various methods, demonstrating that a 1:1 ARA and UR in the crystal forms cytosine-UR hydrogen-bonding interactions, thus constructing supramolecular frameworks by strong π-π stacking interplays; while the nano-cocrystal is block-shaped particles of 562.70 nm with zeta potential -33.40 mV. The properties of cocrystal ARA-UR and its nano-cocrystal in vitro/vivo are comparatively explored by theoretical calculations and experimental analyses, revealing that permeability of both is significantly increased than ARA per se. Notably, the meliorative natures of both the cocrystal and nano-cocrystal in vitro bring excellent antitumor activity, but the latter has greater strengths over the former. More notably, the nano-cocrystal can sustain effective concentration for a relatively longer time, causing lengthened retention time and better absorption in vivo. The contribution offers a fire-new dosage form of ARA for long-lasting delivery, thus filling the vacancy in nanococrystal studies about marine drugs.

Nanoparticles loaded with Daunorubicin as an advanced tool for cancer therapy

Nowadays, with the advent of cutting-edge technologies in the field of biotechnology, some highly advanced medical methods are introduced to treat cancers more efficiently. In the chemotherapy processes, anti-cancer drugs can be encapsulated in a stimuli-responsive coating which is capable of being functionalized by diverse ligands to increase the biocompatibility and control drug release behavior in a targeted drug delivery system. Nanoparticles (NPs) are playing an important role as nanocarriers in chemotherapy procedures, recently, numerous novel drug delivery systems have been studied which employed diverse types of NPs with remarkable structural features like porous nanocarriers with active and extended surface areas to enhance the drug loading and delivery efficacy. In this study, Daunorubicin (DAU) as an effective anti-cancer drug for treating various cancers introduced, and its application for novel drug delivery systems either as a single chemotherapy agent or co-delivery alongside other drugs with diverse NPs has been reviewed.

The effects of intermolecular interactions on the stability and in vitro drug release of daunorubicin/cytarabine co-loaded liposome

Various studies were performed on the intermolecular interactions of daunorubicin (DNR) and cytarabine (Ara-C) co-loaded liposome to predict and elucidate its stability and in vitro drug release behavior. Langmuir monolayer and spectroscopy studies showed interactions between its components. The Langmuir monolayer study and blank liposomes stability study illustrated that interactions between lipids could affect their stability, and the DSPC/DSPG/Chol (7/2/1, mol%) mixed system tended to be thermodynamically and physicochemically stable. The interactions between daunorubicin and copper ions were then investigated by ultraviolet-visible (UV-vis) electronic absorption spectroscopy and circular dichroism (CD) spectroscopy, which revealed that the DNR-Cu complex was composed of daunorubicin and copper ions at a molar ratio of 1:1 or 1:2, and its solubility was related to the acidity of the solution. In vitro release experiment of liposomes with different copper gluconate contents illustrated that the interactions between drugs and copper ions were conducive to the retention and synergetic release of drugs. The stability and release studies of the DSPC/DSPG/Chol (7/2/1, mol%) co-loaded liposome illustrated that it had good storage and plasma stability, and the release behaviors of drugs were pH-related, i.e., drugs could be released faster under acidic condition. These studies indicated that intermolecular interactions could affect the stability and release behavior of the liposome, and a certain ratio of components could be conducive to its stability and synergistic release of drugs.

Bifunctional lipids in tumor vaccines: An outstanding delivery carrier and promising immune stimulator

Cancer is still a major threat for human life, and the cancer immunotherapy can be more optimized to prolong life. However, the effect of immunotherapy is not encouraging. In order to achieve outstanding immune effect, it is necessary to strengthen antigens uptake of antigen presenting cells. Adjuvants were added to vaccines to achieve this purpose, which could be divided into two types: as an immunostimulatory molecule, the innate immunities of the body were triggered; or as a delivery carrier, and antigens were cross-delivery through the "cytoplasmic pathway" and released at a specific location. This paper reviewed the relevant research status of tumor vaccine immune adjuvants in recent years. Among the review, the function, combination strategies and derivatives of lipid A were discussed in detail. In addition, some suggestions on the existing problems and research direction of lipids as tumor vaccine adjuvants were put forward.