Current Drug Delivery - Volume 11, Issue 6, 2014

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 Kaposi’s 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.

Osteomyelitis is characterized by progressive inflammatory bone degeneration. In the management of chronic osteomyelitis, it is necessary to remove the infected bone tissue followed by implantation of an antibiotic releasing biomaterial that can release antibiotic locally for long periods of time. The main carrier used in clinics for this application is polymethylmethacrylate (PMMA) (Eg. Septopal beads). However, major drawback is the need of an additional surgery to remove the beads after therapy, as PMMA is not biodegradable. This necessitates the requirement of biodegradable carrier systems that can release antibiotics and simultaneously support debrided bone formation. This review summarizes biodegradable carrier systems that have been reported for the localised treatment and prophylaxis of osteomyelitis.

Motivated by the success and exhaustive research on carbon nanotubes (CNTs) based drug delivery, graphene, a two-dimensional; honey-comb crystal lattice has emerged as the rising star in recent years. Graphene is a flat monolayer of carbon atoms that holds many promising properties such as unparalleled thermal conductivity, remarkable electronic properties, and most intriguingly higher planar surface and superlative mechanical strength, which are attractive in biotechnological applications. Delivery of anti-cancer drugs using graphene and its derivatives has sparked major interest in this emerging field. The anti-cancer therapies often pose a limitation of insolubility, administration problems and cellpenetration ability. In addition, systemic toxicity caused by lack of selective targeting towards cancer cells and inefficient distribution limits its clinical applications. Graphene nanocomposite is a promising tool to address these drawbacks. This review will focus on various synthesis and functionalization of graphene and graphene oxide for providing better solubility and targeted drug delivery at cancer cells. A more advanced and ‘smart’ graphene hybrid nanostructures that have several functionalities such as stimulus-response mediated delivery, imaging at release sites as well as transfection into cancer cells are also presented. A brief description on the challenges and perspectives for future research in this field is also discussed.

Dental disorders, such as caries, periodontal and endodontic diseases are major public health issues worldwide. In common, they are biofilm-dependent oral diseases, and the specific conditions of oral cavity may develop infectious foci that could affect other physiological systems. Efforts have been made to develop new treatment routes for the treatment of oral diseases, and therefore, for the prevention of some systemic illnesses. New drugs and materials have been challenged to prevent and treat these conditions, especially by means of bacteria elimination. “Recent progresses in understanding the etiology, epidemiology and microbiology of the microbial flora in those circumstances have given insight and motivated the innovation on new therapeutic approaches for the management of the oral diseases progression”. Some of the greatest advances in the medical field have been based in nanosized systems, ranging from the drug release with designed nanoparticles to tissue scaffolds based on nanotechnology. These systems offer new possibilities for specific and efficient therapies, been assayed successfully in preventive/curative therapies to the oral cavity, opening new challenges and opportunities to overcome common diseases based on bacterial biofilm development. The aim of this review is to summarize the recent nanotechnological developments in the drug delivery field related to the prevention and treatment of the major biofilm-dependent oral diseases and to identify those systems, which may have higher potential for clinical use.

Mucosal administration of vaccines is one of the most popular approaches to induce desired immunity against various types of antigen and microbial in central as well as peripheral blood and in most external mucosal surfaces. The oral route is a preferred choice over parenteral route for this purpose mainly due to an ease of administration and therefore, for the possibility of covering large population for mass immunization. Different strategies of mucosal vaccination aimed to prevent colony formation and infection by pathogens and block its development. But a major concern with these vaccines is the degradation of protein components in stomach due to physiological conditions and gastric enzymes. Therefore, surface modified nanoparticles offer a better and stable alternative for efficient delivery and better activation of required immune responses. Natural and synthetic polymers are used to prepare nanoparticulate carrier systems for the development of oral mucosal vaccines. Amongst these, biodegradable polymers based nano-particulate carriers have been explored extensively for the development of delivery systems. Present review summarizes possible approaches and mechanisms for the systemic immunization by oral vaccines and critically discusses various polymers used, different strategies of surface modification to achieve targeting of antigen loaded nanoparticulate carrier at cellular level that are essentially required for a successful mucosal vaccination approach, and future prospects of nanoparticulate system as adjutants in oral mucosal vaccination.

Antimicrobial therapy of infections caused by M. tuberculosis is a challenge due to poor response to therapy and recurrent infections. Under in vitro conditions, antibiotics effectively kill M. tuberculosis within the first two weeks. However, an extended treatment time of 6-9 months is required to eradicate M. tuberculosis infection, mainly due to the intracellular survival of this pathogen and poor penetration of the antibiotics into the intracellular compartment of the host cells. Recent advances in the field of drug delivery have led to the use of different antibiotic incorporated nano- and micro- formulations such as liposomes, polymeric particles, mesoporous silica particles and particulate suspensions for targeted drug delivery applications into the intracellular compartment of the macrophages. The drug incorporated nano- and micro-particles are prone to be easily internalized, which leads to preferential delivery of the drugs into the tissues and organs of interest. Other advantages of these nano- and micro-particles over the free drugs are their comparatively higher stability and bioavailability. This review highlights the current strategies and challenges in treatment, the different antibiotics available, their modes of action, generation and mechanism of drug resistance and recent advances in the intracellular drug delivery using nanoparticles for the treatment of tuberculosis.

Sertaconazole nitrate is a broad spectrum imidazole antifungal agent with antibacterial and anti-inflammatory properties. However, its lipophilic nature and very poor aqueous solubility limit its use in the clinic. The aim of this study was to develop and characterize poly(ethylene glycol)-block-poly(ε-caprolactone) (PEG-b-PCL) polymeric nanomicelles for the solubilization and enhancement of sertaconazole antifungal activity. Sertaconazole was incorporated into PEG-b- PCL polymeric nanomicelles by a co-solvent evaporation method and micelle size, drug loading capacity and drug release properties were determined. The antifungal properties of nanomicelle-loaded drug were evaluated in Fusarium miscanthi, Microsporum canis, and Trichophyton mentagrophytes isolated, respectively from fungal keratitis, ringworm, and tinea corporis. PEG-b-PCL formed nanomicelles in aqueous solution with a diameter ranging from 40-80 nm, depending on the polymer composition and level of drug loading. Drug loading properties of the nanomicelles were dependent on the PCL block molecular weight and drug/polymer weight feed ratio. Drug encapsulation efficiency of up to 85% was achieved and this resulted in more than 80-fold enhancement in sertaconazole aqueous solubility at polymer concentration of 0.2%. Drug release studies showed an initial burst release followed by sustained drug release for 72 hours. In vitro antimycotic studies showed that nanomicelle-incorporated sertaconazole inhibited fungal growth in a concentration dependent manner. Further, it was more effective than the free drug in inhibiting the growth of Fusarium miscanthi and Microsporum canis. These results confirm the utility of PEG-b-PCL nanomicelles in enhancing the aqueous solubility and antifungal activity of sertaconazole or other similar antifungal drugs.

The purpose of this study was to prepare and characterize levocetirizine hydrochloride loaded liposome of by film hydration technique followed by sonication. Sorbitol was added to facilitate the hydration of dried liposome into vesicles or to prepare rehydration system. The liposomes were characterized for size, shape, entrapment efficiency, invitro drug release and stability. The morphology of liposomes was characterized through a phase-contrast microscope and transmission electron microscope. The percent entrapment efficiency and particle size varied between 55.6±0.21 to 81.2±0.52 and 15.73±0.99 to 24.52±0.97 μm, respectively. The drug release increased at higher concentration of phospholipids. On the other hand, the drug release was decreased at higher concentration of cholesterol. The preliminary results of this study suggest that the developed multi-lamellar vesicles containing levocetirizine hydrochloride could enhance drug entrapment efficiency, reduce the initial burst release and modulate the drug release.

Development of colloidal delivery systems has opened new avenues/frontiers for improving drug delivery. Solid lipid nanoparticles have come up as the latest development in the arena of lipid based colloidal delivery systems after nanoemulsion and liposomes ever since their introduction in the early 1990s. In this review, the authors have made efforts to bring forth the essential and practically relevant aspects of SLNs. This review gives an overview of the preparation methods of solid lipid nanoparticles while mainly focussing on their biological applications including their projected applications in drug delivery. This review critically examines the influential factors governing the formation of SLNs and then discussing in detail the several techniques being utilized for their characterization. This review discusses the drug loading and drug release aspects of SLNs as these are useful biocompatible carriers of lipophilic and to a certain extent hydrophilic drugs. An updated list of drugs encapsulated into various lipids to prepare SLN formulations has been provided. Other relevant aspects pertaining to the clinical use of SLN formulations like their sterilization and storage stability have also been explained. A unique facet of this review is the discussion on the challenging issues of in vivo applications and recent progresses in overcoming these challenges which follows in the end.

Curcumin diferuloylmethane is a main yellow bioactive component of turmeric, possess wide spectrum of biological actions. It was found to have anti-inflammatory, antioxidant, anticarcinogenic, antimutagenic, anticoagulant, antifertility, antidiabetic, antibacterial, antifungal, antiprotozoal, antiviral, antifibrotic, antivenom, antiulcer, hypotensive and hypocholesteremic activities. However, the benefits are curtailed by its extremely poor aqueous solubility, which subsequently limits the bioavailability and therapeutic effects of curcumin. Nanotechnology is the available approach in solving these issues. Therapeutic efficacy of curcumin can be utilized effectively by doing improvement in formulation properties or delivery systems. Numerous attempts have been made to design a delivery system of curcumin. Currently, nanosuspensions, micelles, nanoparticles, nano-emulsions, etc. are used to improve the in vitro dissolution velocity and in vivo efficiency of curcumin. This review focuses on the methods to increase solubility of curcumin and various nanotechnologies based delivery systems and other delivery systems of curcumin.

The objective of the present study was to fabricate and evaluate a multiparticulate oral gastroretentive dosage form of baclofen characterized by a central large cavity (hollow core) promoting unmitigated floatation with practical applications to alleviate the signs and symptoms of spasticity and muscular rigidity. Solvent diffusion and evaporation procedure were applied to prepare floating microspheres with a central large cavity using various combinations of ethylcellulose (release retardant) and HPMC K4M (release modifier) dissolved in a mixture of dichloromethane and methanol (2:1). The obtained microspheres (700-1000 µm) exhibit excellent floating ability (86±2.00%) and release characteristics with entrapment efficiency of 95.2±0.32%. Microspheres fabricated with ethylcellulose to HPMC K4M in the ratio 8.5:1.5 released 98.67% of the entrapped drug in 12 h. Muscle relaxation caused by baclofen microspheres impairs the rotarod performance for more than 12 h. Abdominal X-ray images showed that the gastroretention period of the floating barium sulfate- labeled microspheres was no less than 10 h. The buoyant baclofen microspheres provide a promising gastroretentive drug delivery system to deliver baclofen in spastic patients with a sustained release rate.

Purpose: To develop controlled release osmotic pump tablets (COPT) of glipizide (GZ) solid dispersion (SD). Methods: In elementary osmotic pump (EOP) tablets, an osmotic core with the drug is surrounded by a semi-permeable membrane which is drilled with a delivery orifice. COPT tablets eliminate the need of drilling process as controlled release can be achieved by the presence of osmogen in the coating. Poorly water soluble drug molecule cannot give satisfactory drug release hence GZ solid dispersion was prepared in the present study. The SDs having different ratio of drug to Poloxamer (PXM) 188 were prepared by hot melt method and optimized by solubility study, drug content estimation and in vitro dissolution study. Effect of two independent variables, amount of osmogen (potassium chloride) and hydrophilic polymer (polyethylene oxide WSR 303), were investigated using 32 factorial design. Core and coated tablets were evaluated for pharmacotechnical parameters. In-vitro drug release profiles of COPT tablets were compared with marketed with push-pull osmotic pump tablet, Glucotrol XL. Results: Prepared core and coated tablets showed acceptable pharmacotechnical parameters. Drug release was directly proportional to initial level of hydrophilic polymer, but inversely related to the osmogen, confirming osmotic mechanism. Zero order drug release pattern was achieved which was comparable to marketed product. Conclusion: Novel oral controlled release of glipizide was successfully achieved by incorporating glipizide solid dispersion into osmotic system.