Ravindra Dhar Dubey

Paclitaxel formulations: challenges and novel delivery options.

Paclitaxel (PTX), a taxane plant product, is one of the most effective broad-spectrum anti-cancer agents and approved for the treatment of a variety of cancers including ovarian, breast, lung, head and neck as well as Kaposis sarcoma. Poor aqueous solubility and serious side effects associated with commercial preparation of PTX (Taxol®) triggered the development of alternative PTX formulations. Over past three decades, plethora of research work has been published towards the development of cremophor free and efficient formulations. Various nanocarrier systems including nanoparticles, liposomes, micelles, bioconjugates and dendrimers have been employed in order to improve PTX solubility and eliminate undesired side effects. These nanocarriers offer the advantage of high degree of encapsulation and cellular uptake, escape from elimination by P-glycoprotein (P-gp) mediated efflux, and can be explored for targeted drug delivery. The potential of these nanocarriers is reflected by the fact that various nanocarriers of PTX are in different stages of clinical trials and a few have already been commercialized including Abraxane®, Lipusu and Genexol PM®. This review focuses on the various challenges associated with PTX formulation development, limitations of existing formulations and novel approaches for the development of alternative formulations for PTX and also highlights the development of novel formulations in clinical settings.

Advances in P-glycoprotein-based approaches for delivering anticancer drugs: pharmacokinetic perspective and clinical relevance

Introduction: P-glycoprotein (P-gp) is a multi-specific efflux transporter belonging to ATP-binding cassette (ABC) transporter family, encoded by the ABCB1 gene, which significantly impacts the pharmacokinetics as well as multidrug resistance of anticancer drugs. Areas covered: This review explores how human P-gp transporters modulate the pharmacokinetics of anticancer drugs and emerging strategies to modulate their function. The key findings in direct modulation by various P-gp inhibitors on pharmacokinetics of various anticancer P-gp substrates are described. The role of pharmaceutical excipients as P-gp inhibitor with the focus on the recent development in novel drug delivery systems to modulate pharmacokinetics of anticancer drugs is also outlined. Expert opinion: The concomitant use of anticancer P-gp substrate and P-gp inhibitor is an effective and safe way to enhance the bioavailability of anticancer drugs. The poor bioavailability and toxicity of anticancer drugs limit their therapeutic efficacy. These characteristics can be improved by using various nanocarriers which exhibited a high potential to bypass this efflux protein. The best combination of P-gp inhibitor and substrate anticancer drug in a single nanocarrier formulation is a future challenge and is still probably some years away from the marketplace.

Development and evaluation of folate functionalized albumin nanoparticles for targeted delivery of gemcitabine

Gemcitabine is one of the most potent anticancer agents acting on a wide range of solid tumors, however, its use is limited by short half life and high dose leading to serious side effects. The present investigation describes the development and characterization of folate functionalized gemcitabine loaded bovine serum albumin nanoparticles (Fa-Gem-BSANPs). The nanoparticles were prepared by desolvation cross-linking technique and characterized for various parameters including morphology, particle size, zeta potential, drug loading and release profile. The particle size of Gem-BSANPs and Fa-Gem-BSANPs was found to be 159.1±5.29 and 208.7±1.80 nm, respectively. DSC and XRD analysis indicated amorphous nature of the drug within the particles. The encapsulated gemcitabine exhibited less hemolytic properties as compared to native drug. The anticancer activity of Fa-Gem-BSANPs was evaluated in folate receptor over expressing cell lines (Ovcar-5 and MCF-7) and folate receptor deficient cell line (MIAPaCa-2). The Fa-Gem-BSANPs showed superior anticancer activity as compared to Gem-BSANPs in Ovcar-5 and MCF-7 cells while no significant difference in cytotoxicity was found with MIAPaCa-2 cells. Confocal microscopy indicated facilitated intracellular uptake of Fa-Gem-BSANPs in MCF-7, which in turn result in a higher potential for apoptosis. Further, Fa-Gem-BSANPs exhibited improved anti-tumor activity in Ehrlich solid tumor model in mice. In conclusion, our study indicates that folate functionalized nanoparticles confer enhance cellular uptake and cytotoxicity for gemcitabine.

Co-formulation of P-glycoprotein Substrate and Inhibitor in Nanocarriers: An Emerging Strategy for Cancer Chemotherapy

Scientific community is striving to understand the role of P-glycoprotein (P-gp) in drug discovery programs due to its impact on pharmacokinetic and multi-drug resistance (MDR) of anticancer drugs. A number of efforts to resolve the crystal structure and understanding the mechanism of P-gp mediated efflux have been made. Several generations of Pgp inhibitors have been developed to tackle this multi-specific efflux protein. Unfortunately, these inhibitors lack selectivity, exhibit poor solubility and severe pharmacokinetic interactions restricting their clinical use. The nanocarrier drug delivery systems (NDDS) are receiving increasing attention for P-gp modulating activity of pharmaceutical excipients which are used in their fabrication. In addition, NDDS can enhance the solubility and exhibited ability to bypass P-gp mediated efflux. The co-formulation of P-gp inhibitors and substrate anticancer drugs in single drug delivery system offers the advantage of bypassing P-gp mediated drug efflux as well as inhibiting the P-gp. Moreover, severe pharmacokinetic interactions between P-gp inhibitor and substrate anticancer drugs could be avoided by using this strategy. In this article we describe the co-formulation strategies using nanocarriers for modulation of pharmacokinetics as well as multi-drug resistance of anticancer drugs along with the challenges in this area.

Development and evaluation of paclitaxel loaded PLGA:poloxamer blend nanoparticles for cancer chemotherapy.

This investigation described the development of novel PLGA:poloxamer blend nanoparticles for intravenous administration of paclitaxel in order to limit the cremophor-associated adverse effects. The developed formulation was well-characterized using various techniques including scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy and differential scanning calorimetry. The nanoparticles had an average particle size around 180nm and zeta potential of -22.7mV. The in vitro release study of nanoparticles exhibited biphasic release pattern. The non-hemolytic potential of the nanoparticles indicated the suitability of the developed formulation for intravenous administration. The PLGA:poloxamer blend nanoparticles showed significantly improved cytotoxicity in cell lines (MCF-7 and Colo-205), as compared to free drug. Further, the developed formulation was stable under the accelerated storage conditions. In conclusion, the results indicated that the developed polymeric formulation is a novel and potential alternative for the paclitaxel delivery.

Reduced toxicological manifestations of cisplatin following encapsulation in folate grafted albumin nanoparticles.

AIMS Cisplatin is one of the most potent chemotherapeutic agents acting against a variety of tumors, however, its use is mainly limited due to the dose limiting toxicities and acquired resistance to cisplatin. Folate functionalized albumin nanoparticles were developed for targeted delivery of drug to limit the adverse effects of cisplatin. MAIN METHODS Cisplatin loaded nanoparticles functionalized with folate (CP-FA-BSA-NPs) were developed and characterized for various parameters. In order to investigate the targeting ability of folate conjugated nanoparticles, in vitro cellular uptake study was performed in folate receptor over expressing cells (MCF-7). Further, blood urea nitrogen (BUN) level, plasma creatinine level, body weight and kidney weight of the mice were measured followed by histopathological examination of various tissues to have an insight into the potential of developed formulation in the reduction of drug associated adverse effects. KEY FINDINGS The cellular uptake studies demonstrated higher internalization of folate conjugated nanoparticles as compared to plain counterpart (CP-BSA-NPs). Following two cycles of cisplatin treatment, a week apart, BUN and plasma creatinine level were found to be significantly higher in case of free cisplatin as compared to saline, CP-BSA-NPs and CP-FA-BSA-NPs treated groups. Body weight and kidney weight of free cisplatin treated mice were significantly reduced as compared to other group. Histopathological examination of kidney from CP-BSA-NPs and CP-FA-BSA-NPs treated groups revealed no kidney damage, however, a sign of nephrotoxicity was observed in the case of free cisplatin. SIGNIFICANCE The results demonstrated the potential of developed formulation in reducing the adverse effects of cisplatin.

Synthesis, characterization and augmented anticancer potential of PEG-betulinic acid conjugate

Betulinic acid (BA), a pentacyclic lupine-type triterpene, is reported to inhibit cell growth in a variety of cancers. However, its efficacy is limited by its poor aqueous solubility and relatively short half-life. In this study, BA-monomethoxy polyethylene glycol (mPEG) conjugate was synthesized by covalent coupling the C-28 carboxylic acid position of BA with amine groups of mPEG, in order to improve its solubility and anticancer efficacy. mPEG-BA conjugate was characterized using various analytical techniques including NMR, FT-IR and MALDI-MS. The mPEG-BA conjugate was cytotoxic, demonstrated internalization and induced cell apoptosis in Hep3B and Huh7 hepatic cancer cells. The western-blot analysis revealed, marked decrease in Bcl-2/Bax ratio, and increase in cleaved-PARP and cleaved-caspase-3 expressions. In vivo studies in Ehrlich ascites tumor (EAT) model following intravenous administration demonstrated significant reduction in tumor volume in case of PEGylated BA as compare to native BA. Furthermore, PEGylated BA treated EAT mice showed no biochemical and histological toxicities. These findings demonstrate the potential of PEGylated BA in cancer therapy, with improved water solubility and efficacy.

PLGA nanoparticles augmented the anticancer potential of pentacyclic triterpenediol in vivo in mice

A pentacyclic triterpenediol (TPD) from Boswellia serrata exhibited a good anticancer potential preclinically, however, it has low aqueous solubility and high lipophilicity, which therefore, necessitate suitable formulation development for in vivo application. In the present study TPD-loaded PLGA nanoparticles (TPD NPs) were prepared by an emulsion–diffusion–evaporation technique which exhibited an average particle size in the order of about 161 nm as confirmed by dynamic light scattering (DLS) and atomic force microscopy (AFM). The thermal analysis confirms that the TPD was entrapped into the NPs in an amorphous form. In vitro cell culture experiments indicated higher cellular cytotoxicity of the TPD-loaded NPs over free TPD in MCF-7 and OVCAR-5 cells. The higher cytotoxicity of TPD NPs was attributed to enhanced cellular apoptosis, loss of membrane potential and generation of high reactive oxygen species (ROS). The TPD-loaded NPs demonstrated a significantly higher in vivo anticancer potential as compared to TPD solution in the Ehrlich ascites tumor (EAT) model following intraperitoneal administration. Furthermore, no hematological and biochemical toxicity in EAT bearing mice was observed after the treatment. The results showed that the developed PLGA-NPs could be a potential option for improved TPD delivery in cancer chemotherapy.

Development and evaluation of long-circulating nanoparticles loaded with betulinic acid for improved anti-tumor efficacy

The clinical application of betulinic acid (BA), a natural pentacyclic triterpenoid with promising antitumor activity, is hampered due to its extremely poor water solubility and relatively short half-life in the systemic circulation. In order to address these issues, herein, we developed betulinic acid loaded polylactide-co-glycolide- monomethoxy polyethylene glycol nanoparticles (PLGA-mPEG NPs). The PLGA-mPEG co-polymer was synthesized and characterized using NMR and FT-IR. BA loaded PLGA-mPEG NPs were prepared by an emulsion solvent evaporation method. The developed nanoparticles had a desirable particle size (∼147nm) and exhibited uniform spherical shape under transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The PLGA-mPEG NPs were able to decrease the uptake by macrophages (i.e. J774A.1 and Raw 264.7 cells) as compared to PLGA nanoparticles. In vitro cytotoxicity in MCF7 and PANC-1 cells demonstrated enhanced cytotoxicity of BA loaded PLGA-mPEG NPs as compared to free BA. The cellular uptake study in both the cell lines demonstrated time dependent uptake behavior. The enhanced cytotoxicity of BA NPs was also supported by increased cellular apoptosis, mitochondrial membrane potential loss, generation of high reactive oxygen species (ROS) and cell cycle arrest. Further, intravenous pharmacokinetics study revealed that BA loaded PLGA-mPEG NPs could prolong the circulation of BA and remarkably enhance half-life by ∼7.21 folds. Consequently, in vivo studies in Ehrlich tumor (solid) model following intravenous administration demonstrated superior antitumor efficacy of BA NPs as compared to native BA. Moreover, BA NPs treated Ehrlich tumor mice demonstrated no biochemical, hematological and histological toxicities. These findings collectively indicated that the BA loaded PLGA-mPEG NPs might serve as a promising nanocarrier for improved therapeutic efficacy of betulinic acid.

Therapeutic applications of betulinic acid nanoformulations

Betulinic acid (BA), a naturally occurring plant‐derived pentacyclic triterpenoid, has gained attention in recent years owing to its broad‐spectrum biological and medicinal properties. Despite the pharmacological activity of BA, it has been associated with some drawbacks, such as poor aqueous solubility and short half‐life in vivo, which limit therapeutic application. To solve these problems, much work in recent years has focused on enhancing BAs aqueous solubility, half‐life, and efficacy by using nanoscale drug delivery systems. Several different kinds of nanoscale delivery systems—including polymeric nanoparticles, magnetic nanoparticles, liposomes, polymeric conjugates, nanoemulsions, cyclodextrin complexes, and carbon nanotubes—have been developed for the delivery of BA. Here, we focus on the recent developments of novel nanoformulations used to deliver BA in order to improve its efficacy.