Rajan Swami

Lymphatic system: a prospective area for advanced targeting of particulate drug carriers.

Introduction: The lymphatic system has a critical role in the immune systems recognition and response to disease and it is an additional circulatory system throughout the entire body. Extensive multidisciplinary investigations have been carried out in the area of lymphatic delivery, and lymphatic targeting has attracted a lot of attention for providing preferential chemotherapy and improving bioavailability of drugs that undergo hepatic first-pass metabolism. Areas covered: This review focuses on progress in the field of lymphatic therapeutics and diagnosis. Moreover, the anatomy and physiology of the lymphatic system, particulate drug carriers and different physicochemical parameters of both modified and unmodified particulate drug carriers and their effect on lymphatic targeting are addressed. Expert opinion: Particulate drug carriers have encouraged lymphatic targeting, but there are still challenges in targeting drugs and bioactives to specific sites, maintaining desired action and crossing all the physiological barriers. Lymphatic therapy using drug-encapsulated lipid carriers, especially liposomes and solid lipid nanoparticles, emerges as a new technology to provide better penetration into the lymphatics where residual disease exists. Size is the most important criteria when designing nanocarriers for targeting lymphatic vessels as the transportation of these particles into lymphatic vessels is size dependent. By increasing our understanding of lymphatic transport and uptake, and the role of lymphatics in various diseases, we can design new therapeutics for effective disease control.

Lactoferrin bioconjugated solid lipid nanoparticles: a new drug delivery system for potential brain targeting.

Abstract Background: Delivery of drugs to brain is a subtle task in the therapy of many severe neurological disorders. Solid lipid nanoparticles (SLN) easily diffuse the blood–brain barrier (BBB) due to their lipophilic nature. Furthermore, ligand conjugation on SLN surface enhances the targeting efficiency. Lactoferin (Lf) conjugated SLN system is first time attempted for effective brain targeting in this study. Purpose: Preparation of Lf-modified docetaxel (DTX)-loaded SLN for proficient delivery of DTX to brain. Methods: DTX-loaded SLN were prepared using emulsification and solvent evaporation method and conjugation of Lf on SLN surface (C-SLN) was attained through carbodiimide chemistry. These lipidic nanoparticles were evaluated by DLS, AFM, FTIR, XRD techniques and in vitro release studies. Colloidal stability study was performed in biologically simulated environment (normal saline and serum). These lipidic nanoparticles were further evaluated for its targeting mechanism for uptake in brain tumour cells and brain via receptor saturation studies and distribution studies in brain, respectively. Results: Particle size of lipidic nanoparticles was found to be optimum. Surface morphology (zeta potential, AFM) and surface chemistry (FTIR) confirmed conjugation of Lf on SLN surface. Cytotoxicity studies revealed augmented apoptotic activity of C-SLN than SLN and DTX. Enhanced cytotoxicity was demonstrated by receptor saturation and uptake studies. Brain concentration of DTX was elevated significantly with C-SLN than marketed formulation. Conclusions: It is evident from the cytotoxicity, uptake that SLN has potential to deliver drug to brain than marketed formulation but conjugating Lf on SLN surface (C-SLN) further increased the targeting potential for brain tumour. Moreover, brain distribution studies corroborated the use of C-SLN as a viable vehicle to target drug to brain. Hence, C-SLN was demonstrated to be a promising DTX delivery system to brain as it possessed remarkable biocompatibility, stability and efficacy than other reported delivery systems.

Adenosine conjugated lipidic nanoparticles for enhanced tumor targeting.

Delivering chemotherapeutics by nanoparticles into tumor is impeded majorly by two factors: nonspecific targeting and inefficient penetration. Targeted delivery of anti-cancer agents solely to tumor cells introduces a smart strategy because it enhances the therapeutic index compared with untargeted drugs. The present study was performed to investigate the efficiency of adenosine (ADN) to target solid lipid nanoparticles (SLN) to over expressing adenosine receptor cell lines such as human breast cancer and prostate cancer (MCF-7 and DU-145 cells), respectively. SLN were prepared by emulsification and solvent evaporation process using docetaxel (DTX) as drug and were characterized by various techniques like dynamic light scattering, differential scanning calorimeter and transmission electron microscopy. DTX loaded SLNs were surface modified with ADN, an adenosine receptors ligand using carbodiimide coupling. Conjugation was confirmed using infrared spectroscopy and quantified using phenol-sulfuric acid method. Conjugated SLN were shown to have sustained drug release as compared to unconjugated nanoparticles and drug suspension. Compared with free DTX and unconjugated SLN, ADN conjugated SLN showed significantly higher cytotoxicity of loaded DTX, as evidenced by in vitro cell experiments. The IC50 was 0.41 μg/ml for native DTX, 0.30 μg/ml for unconjugated SLN formulation, and 0.09 μg/ml for ADN conjugated SLN formulation in MCF-7 cell lines. Whereas, in DU-145, there was 2 fold change in IC50 of ADN-SLN as compared to DTX. IC50 was found to be 0.44 μg/ml for free DTX, 0.39 μg/ml for unconjugated SLN and 0.22 μg/ml for ADN-SLN. Annexin assay and cell cycle analysis assay further substantiated the cell cytotoxicity. Fluorescent cell uptake and competitive ligand-receptor binding assay corroborated the receptor mediated endocytosis pathway indicated role of adenosine receptors in internalization of conjugated particles. Pharmacokinetic studies of lipidic formulations depicted significant improvement in pharmacokinetic parameters than marketed formulation. ADN conjugated SLN proved to be an efficient drug delivery vehicle. Hence, ADN can be used as a potential ligand to target breast and prostate cancer.

Diseases originate and terminate by genes: unraveling nonviral gene delivery

The world is driving in to the era of transformation of chemical therapeutic molecules to biological genetic material therapeutics, and that is where the biological drugs especially “genes” come into existence. These genes worked as “magical bullets” to specifically silence faulty genes responsible for progression of diseases. Viral gene delivery research is far ahead of nonviral gene delivery technique. However, with more advancement in polymer science, new ways are opening for better and efficient nonviral gene delivery. But efficient delivery method is always considered as a bottleneck for gene delivery as success of which will decide the fate of gene in cells. During the past decade, it became evident that extracellular as well as intracellular barriers compromise the transfection efficiency of nonviral vectors. The challenge for gene therapy research is to pinpoint the rate-limiting steps in this complex process and implement strategies to overcome the biological physiochemical and metabolic barriers encountered during targeting. The synergy between studies that investigate the mechanism of breaking in and breaking out of nonviral gene delivery carrier through various extracellular and intracellular barriers with desired characteristics will enable the rational design of vehicles and revolutionize the treatment of various diseases.

p-Aminophenyl-α-D-mannopyranoside engineered lipidic nanoparticles for effective delivery of docetaxel to brain.

Lipidic systems are considered to be the most promising carrier for drug delivery to brain. Metabolic substrates like carbohydrates and amino acids are able to traverse the blood-brain barrier (BBB) by specific carrier-mediated transport systems like glucose transporters present on the both luminal and abluminal side of the BBB. With this objective, the docetaxel (DTX) loaded solid lipidic nanoparticles were formulated and surface modified with a mannose derived ligand p-aminophenyl-α-D-mannopyranoside (MAN) to develop MAN conjugated lipidic nanoparticles for targeting DTX to brain. Lipidic nanoparticles were prepared using emulsification and solvent evaporation method using stearic acid as charge modifying lipid and conjugated with MAN using carbodimide coupling. These lipidic nanoparticles were successfully characterized using various techniques like DLS, TEM, DSC and FTIR spectroscopy. Cytotoxicity and cell uptake unveiled enhanced efficacy of conjugated lipidic nanoparticles. Pharmacokinetic and brain distribution studies demonstrated increased DTX concentrations using lipidic nanoparticles in brain and conjugating MAN on surface of lipidic nanoparticles further augmented the inflow of the drug to brain. Present study revealed the prospective of mannose analog, MAN-conjugated lipidic nanoparticles as efficient vehicle for anticancer drug delivery to brain.

p-Hydroxy benzoic acid-conjugated dendrimer nanotherapeutics as potential carriers for targeted drug delivery to brain: an in vitro and in vivo evaluation

Dendrimers which are discrete nanostructures/nanoparticles are emerging as promising candidates for many nanomedicine applications. Ligand-conjugated dendrimer facilitate the delivery of therapeutics in a targeted manner. Small molecules such as p-hydroxyl benzoic acid (pHBA) were found to have high affinity for sigma receptors which are prominent in most parts of central nervous system and tumors. The aim of this study was to synthesize pHBA-dendrimer conjugates as colloidal carrier for site-specific delivery of practically water insoluble drug, docetaxel (DTX) to brain tumors and to determine its targeting efficiency. pHBA, a small molecule ligand was coupled to the surface amine groups of generation 4-PAMAM dendrimer via a carbodiimide reaction and loaded with DTX. The conjugation was confirmed by 1HNMR and FT-IR spectroscopy. In vitro release of drug from DTX-loaded pHBA-conjugated dendrimer was found to be less as compared to unconjugated dendrimers. The prepared drug delivery system exhibited good physico-chemical stability and decrease in hemolytic toxicity. Cell viability and cell uptake studies were performed against U87MG human glioblastoma cells and formulations exerted considerable anticancer effect than plain drug. Conjugation of dendrimer with pHBA significantly enhanced the brain uptake of DTX which was shown by the recovery of a higher percentage of the dose from the brain following administration of pHBA-conjugated dendrimers compared with unconjugated dendrimer or formulation in clinical use (Taxotere®). Therefore, pHBA conjugated dendrimers could be an efficient delivery vehicle for the targeting of anticancer drugs to brain tumors.

Polymer–Drug Conjugate in Focal Drug Delivery

The area of polymer–drug conjugates is expanding spectacularly in recent years. From macromolecular prodrugs of established anticancer agents to novel targeted polymeric drug conjugate systems, their application has expanded exponentially. Delivery of new anticancer agents, combination therapies, treatment of diseases other than cancer, and novel polymer architectures are highly exciting and promising areas. It is hoped that in the next decade, some of these new approaches will reach clinical evaluation and few will see the light of marketing phase. The successful development of first-generation polymer–drug conjugates in the mid-1980s and 1990s has inspired more recent studies assessing their potential as drug delivery platforms for combination therapy. These early works unveiled unexpected therapeutic benefits but raised new issues, in particular in relation to “system design.” A better understanding of how drug combinations impact on cellular and molecular mechanisms is needed to rationally design new therapeutics. In nutshell it is to be believed that the interdisciplinary scientific approach to the applications of polymer–drug conjugate (PDC) will result in their translation into the clinic within this decade.

ε-Poly-L-Lysine/Plasmid DNA nanoplexes for efficient gene delivery in-vivo

&NA; The present work addresses the development and characterization of &egr;‐Poly‐L‐Lysine/pDNA polyplexes and evaluation for their improved transfection efficacy and safety as compared to polyplexes prepared using Poly‐L‐Lysine and SuperFect®. Self‐assembling polyplexes were prepared by varying the N/P ratio to obtain the optimum size, a net positive zeta potential and gel retardation. The stability in presence of DNase I and serum was assured using gel retardation assay. Their appreciable uptake in MCF‐7 and 3.5, 3.79 and 4.79‐fold higher transfection compared to PLL/pDNA polyplexes and 1.60, 1.53 and 1.79‐fold higher transfection compared to SuperFect®/pDNA polyplexes in MCF‐7, HeLa and HEK‐293 cell lines respectively, affirmed the enhanced transfection of &egr;‐PLL/pDNA polyplexes which was well supported with in vivo transfection and gene expression studies. The <8% in vitro hemolysis and >98% viability of MCF‐7, HeLa and HEK‐293 cells in presence of &egr;‐PLL/pDNA polyplexes addressed their safety, which was also ensured using in vivo toxicity studies, where hemocompatibility, unaltered levels of biochemical markers and histology of vital organs confirmed &egr;‐PLL to be an effective and safer alternative for non‐viral genetic vectors.

Amphotericin B Loaded Chitosan Nanoparticles: Implication of Bile Salt Stabilization on Gastrointestinal Stability, Permeability and Oral Bioavailability

Through current investigation, we presented a lucrative way to formulate amphotericin B loaded bile salt stabilized carbohydrate polymer i.e. chitosan nanoparticles (NPs) for enhancing gastrointestinal stability of NPs thereby increasing the oral bioavailability of the drug. NPs were prepared using ionic gelation method, and stabilized using bile salt to provide gastric pH stability to chitosan NPs. NPs were optimized on different parameters such as particle size, encapsulation efficiency and estimated for their in vitro and in vivo performance. Developed NPs presented a higher stability in gastrointestinal milieu, reduced haemolytic toxicity and significantly higher uptake in Caco-2 cell lines followed by increased bioavailability as compared to naive drug, marketed formulation i.e. Fungizone® and uncoated chitosan NPs. Biochemical parameters and histology further substantiated the lower toxicity. In nutshell, the present research explored the bioadhesive and higher uptake potential of cationic carbohydrate polymer at the same time along with bile salts for stabilization of NPs in gastric milieu.

Improved Oral Bioavailability, Therapeutic Efficacy, and Reduced Toxicity of Tamoxifen-Loaded Liquid Crystalline Nanoparticles

Present investigation deals with formulation and evaluation of tamoxifen (TMX)-loaded liquid crystalline nanoparticles (TMX-LCNPs) for improving oral bioavailability and safety of the existing treatment. Hexagonal Glyceryl monooleate-based TMX-LCNPs (GLCNPs) and Phytantriol-based TMX-LCNPs (PLCNPs) were prepared by dilution-through-hydrotrope method for oral administration. Oleic acid was incorporated in the lipid matrix to enhance the drug loading in the LCNPs. Optimized LCNPs displayed small particle size with a narrow distribution, sustained drug release and high gastrointestinal stability. TMX-LCNPs were found to be considerably higher cytotoxic to MCF-7 cells as compared to free TMX. Substantial fold enhancement in oral bioavailability (~7- and ~5-folds with TMX-GLCNPs and TMX-PLCNPs, respectively) was evident followed by significant reduction in tumor burden with lesser hepatotoxicity. Out of the two LCNP formulations, PLCNPs were found to be better in convalescing the disease.