Studies on biodegradable polymeric nanoparticles of risperidone: in vitro and in vivo evaluation

Insights on Development Aspects of Polymeric Nanocarriers: The Translation from Bench to Clinic

Scientists are focusing immense attention on polymeric nanocarriers as a prominent delivery vehicle for several biomedical applications including diagnosis of diseases, delivery of therapeutic agents, peptides, proteins, genes, siRNA, and vaccines due to their exciting physicochemical characteristics which circumvent degradation of unstable drugs, reduce toxic side effects through controlled release, and improve bioavailability. Polymers-based nanocarriers offer numerous benefits for in vivo drug delivery such as biocompatibility, biodegradability, non-immunogenicity, active drug targeting via surface modification, and controlled release due to their pH-and thermosensitive characteristics. Despite their potential for medicinal use, regulatory approval has been achieved for just a few. In this review, we discuss the historical development of polymers starting from their initial design to their evolution as nanocarriers for therapeutic delivery of drugs, peptides, and genes. The review article also expresses the applications of polymeric nanocarriers in the pharmaceutical and medical industry with a special emphasis on oral, ocular, parenteral, and topical application of drugs, peptides, and genes over the last two decades. The review further examines the practical, regulatory, and clinical considerations of the polymeric nanocarriers, their safety issues, and directinos for future research.

Design and physico-mechanical evaluation of fast-dissolving valsartan polymeric drug delivery system by electrospinning method

Objective(s):

Chronic hypertension is a pervasive morbidity and the leading risk factor for cardiovascular diseases. Valsartan, as an antihypertensive drug, has low solubility and bioavailability. The application of orodispersible films of valsartan is suggested to improve its bioavailability. With this dosage form, the drug dissolves rapidly in saliva and is absorbed readily without the need for water.

Materials and Methods:

For this purpose, valsartan with polyvinylpyrrolidone (PVPK90) polymer were exposed to the electrospinning technique to construct orodispersible nanofilms. The optimum obtained nanofiber, selected by Design-Expert software, was evaluated in terms of mechanical strength for evaluation of the flexibility and fragility of the nanofibers. The drug content, wettability, and disintegration tests, as well as the release assessment of the nanofibers, were performed followed by DSC, FTIR, and XRD assays.

Results:

The uniform nanofibers’ diameter increased with the increase of the polymer concentration. The tensile test verified a stress reduction at the yield point as the polymer concentration increased. Then, the 492 nm nanofiber with above 90% drug encapsulation, containing 8% polymer and 18% valsartan made below 9 kV, was selected. The wetting time was less than 30 sec and over 90% of the drug was released in less than 2 min. The XRD and DSC studies also confirmed higher valsartan solubility due to the construction alternations in nanofibers. The FTIR examination indicated the chemical bonding between the drug and the polymer.

Conclusion:

The selected nanofibers of valsartan present the essential drug feature and acceptable drug release for further investigations.

Applications of innovative technologies to the delivery of antipsychotics

Psychosis is a high-incidence pathology associated with a profound alteration in the perception of reality. The limitations of drugs available on the market have stimulated the search for alternative solutions to achieve effective antipsychotic therapies. In this review, we evaluate innovative formulations of antipsychotic drugs developed through the application of modern pharmaceutical technologies, including classes of micro and nanocarriers, such as lipid formulations, polymeric nanoparticles (NPs), solid dispersions, and cyclodextrins (CDs). We also consider alternative routes of administration to the oral and parenteral ones currently used. Improved solubility, stability of preparations, and pharmacokinetic (PK) and pharmacodynamic (PD) parameters confirm the potential of these new formulations in the treatment of psychotic disorders.

Formulation design, optimization and in vivo evaluation of oral co-encapsulated resveratrol-humic acid colloidal polymeric nanocarriers

The study aims at formulation and optimization of resveratrol and humic acid co-encapsulated colloidal polymeric nanocarriers to improve stability, oral bioavailability, and antiradical activity of water-insoluble, resveratrol. The eudragit E100 polymeric material was used to fabricate resveratrol and humic acid co-encapsulated oral colloidal polymeric nanocarriers (Res-HA-co-CPNs) using emulsification-diffusion-evaporation method. Taguchi orthogonal array design was employed to check the effect of formulation factors on in vitro physicochemical characteristics. The optimized formulation was further evaluated for oral bioavailability as well as for antiradical potential. Optimized Res-HA-co-CPNs demonstrated spherical and smooth surface including mean particle size, 120.56 ± 18.8 nm; polydispersity index, 0.122; zeta potential, +38.25 mV; and entrapment efficiency, 82.37 ± 1.49%. Solid-state characterization confirmed the amorphous characteristic of optimized Res-HA-co-CPNs. In vitro release profile of Res-HA-co-CPNs showed sustained release behavior up to 48 h and CPNs were found to remain stable at the refrigerated condition for 6 months. In vivo pharmacokinetic studies revealed significant (p < 0.05) improvement of ∼62.76-fold in oral bioavailability. The radical-scavenging activity was found to be increased with time and after 72 h, it was analogous to pure Res. IC₅₀ values were reported to be decreased with time. Henceforth, developed Res-HA-co-CPNs was proven to be a proficient dosage form to increase stability, oral bioavailability, and antiradical activity of resveratrol.HighlightsResveratrol-humic acid co-encapsulated colloidal polymeric nanocarriers (Res-HA-co-CPNs) were fabricated by emulsification-diffusion-evaporation method and optimized by Taguchi orthogonal array design.The Res-HA-co-CPNs revealed favorable mean particle size and percent encapsulation efficiency with a spherical and smooth surface.The Res-HA-co-CPNs showed diffusion-controlled release of Res and were found to be stable at the refrigerated condition for 6 months.The optimized Res-HA-co-CPNs demonstrated significantly (p < 0.05) higher oral bioavailability with respect to pure Res and PM.The optimized Res-HA-co-CPNs demonstrated higher radical-scavenging activity with respect to time.

Nanomedicine against Alzheimer's and Parkinson's Disease

Alzheimer's and Parkinson's are the two most rampant neurodegenerative disorders worldwide. Existing treatments have a limited effect on the pathophysiology but are unable to fully arrest the progression of the disease. This is due to the inability of these therapeutic molecules to efficiently cross the blood-brain barrier. We discuss how nanotechnology has enabled researchers to develop novel and efficient nano-therapeutics against these diseases. The development of nanotized drug delivery systems has permitted an efficient, site-targeted, and controlled release of drugs in the brain, thereby presenting a revolutionary therapeutic approach. Nanoparticles are also being thoroughly studied and exploited for their role in the efficient and precise diagnosis of neurodegenerative conditions. We summarize the role of different nano-carriers and RNAi-conjugated nanoparticle-based therapeutics for their efficacy in pre-clinical studies. We also discuss the challenges underlying the use of nanomedicine with a focus on their route of administration, concentration, metabolism, and any toxic effects for successful therapeutics in these diseases.

Amazonia Products in Novel Lipid Nanoparticles for Fucoxanthin Encapsulation

Lipid nanoparticles (LNs) are traditional systems able to effectively increase skin hydration. However, due to its reduced viscosity, LNs suspensions are less attractive for skin administration. To overcome this disadvantage, the LN were incorporated in the semi-solid formulation is easy manipulation. This study demonstrated that it is possible to obtain novel LN-loaded fucoxanthin (LN-FUCO) for topical administration containing a combination of bacuri butter and tucumã oil prepared by high shear homogenization for improved stability. The particle size was found to be 243.0 nm and the entrapment efficiency up to 98% of FUCO was incorporated and achieved the suitability of formula. The LN-FUCO hydrogel characteristics of slight acidity, drug content near 100%, and nanometric mean size assure to this formulation high compatibility to dermal application. Photostability assay by UVA, LN-FUCO, and LN-FUCO hydrogel improved photostability and conferred greater protection against FUCO degradation. The results obtained from in vitro skin permeation studies presented a significant difference between LN-FUCO hydrogel and FUCO (p < 0.05), with no detection of the drug in the receptor medium. Therefore, high shear homogenization is demonstrated to be a simple, available, and effective method to prepare high-quality LN-FUCO hydrogel for topical application.

A window into the brain: Tools to assess pre-clinical efficacy of biomaterials-based therapies on central nervous system disorders

Therapeutic conveyance into the brain is a cardinal requirement for treatment of diverse central nervous system (CNS) disorders and associated pathophysiology. Effectual shielding of the brain by the blood-brain barrier (BBB) sieves out major proportion of therapeutics with the exception of small lipophilic molecules. Various nano-delivery systems (NDS) provide an effective solution around this obstacle owing to their small size and targeting properties. To date, these systems have been used for several pre-clinical disease models including glioma, neurodegenerative diseases and psychotic disorders. An efficacy screen for these systems involves a test battery designed to probe into the multiple facets of therapeutic delivery. Despite their wide application in redressing various disease targets, the efficacy evaluation strategies for all can be broadly grouped into four modalities, namely: histological, bio-imaging, molecular and behavioural. This review presents a comprehensive insight into all of these modalities along with their strengths and weaknesses as well as perspectives on an ideal design for a panel of tests to screen brain nano-delivery systems.

Topical phenytoin nanostructured lipid carriers: design and development

Phenytoin (PHT) is an antiepileptic drug that was reported to exhibit high wound healing activity. Nevertheless, its limited solubility, bioavailability, and inefficient distribution during topical administration limit its use. Therefore, this study aims to develop, characterize nanostructured lipid carriers (NLCs), and evaluate their potential in topical delivery of PHT to improve the drug entrapment efficiency and sustained release. The NLCs were prepared by hot homogenization followed by ultra sonication method using 2³ factorial design. NLC formulations were characterized regarding their particle size (PS), zeta potential (ZP), entrapment efficiency percent (%EE), surface morphology, physicochemical stability, and in vitro release studies. The optimized NLC (F7) was further incorporated in 1%w/v carbopol gel and then characterized for appearance, pH, viscosity, stability, and in vitro drug release. The prepared NLCs were spherical in shape and possessed an average PS of 121.4-258.2 nm, ZP of (-15.4)-(-32.2) mV, and 55.24-88.80 %EE. Solid-state characterization revealed that the drug is dispersed in an amorphous state with hydrogen bond interaction between the drug and the NLC components. NLC formulations were found to be stable at 25 °C for six months. The stored F7-hydrogel showed insignificant changes in viscosity and drug content (p>.05) up to six months at 25 °C that pave a way for industrial fabrication of efficient PHT products. In vitro release studies showed a sustained release from NLC up to 48 h at pH 7.4 following non-Fickian Higuchi kinetics model. These promising findings encourage the potential use of phenytoin loaded lipid nanoparticles for future topical application.

Development and statistical optimization of nefopam hydrochloride loaded nanospheres for neuropathic pain using Box-Behnken design

Nefopam hydrochloride (NFH) is a non-opioid centrally acting analgesic drug used to treat chronic condition such as neuropathic pain. In current research, sustained release nefopam hydrochloride loaded nanospheres (NFH-NS) were auspiciously synthesized using binary mixture of eudragit RL 100 and RS 100 with sorbitan monooleate as surfactant by quasi solvent diffusion technique and optimized by 35 Box-Behnken designs to evaluate the effects of process and formulation variables. Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetric (DSC) and X-ray diffraction (XRD) affirmed absence of drug-polymer incompatibility and confirmed formation of nanospheres. Desirability function scrutinized by design-expert software for optimized formulation was 0.920. Optimized batch of NFH-NS had mean particle size 328.36 nm ± 2.23, % entrapment efficiency (% EE) 84.97 ± 1.23, % process yield 83.60 ± 1.31 and % drug loading (% DL) 21.41 ± 0.89. Dynamic light scattering (DLS), zeta potential analysis and scanning electron microscopy (SEM) validated size, charge and shape of nanospheres, respectively. In-vitro drug release study revealed biphasic release pattern from optimized nanospheres. Korsmeyer Peppas found excellent kinetics model with release exponent less than 0.45. Chronic constricted injury (CCI) model of optimized NFH-NS in Wistar rats produced significant difference in neuropathic pain behavior (p < 0.05) as compared to free NFH over 10 h indicating sustained action. Long term and accelerated stability testing of optimized NFH-NS revealed degradation rate constant 1.695 × 10-4 and shelf-life 621 days at 25 ± 2 °C/60% ± 5% RH.

Oral nanomedicine approaches for the treatment of psychiatric illnesses

Psychiatric illnesses are a leading cause of disability and morbidity globally. However, the preferred orally dosed pharmacological treatment options available for depression, anxiety and schizophrenia are often limited by factors such as low drug aqueous solubility, food effects, high hepatic first-pass metabolism effects and short half-lives. Furthermore, the discovery and development of more effective psychotropic agents has stalled in recent times, with the majority of new drugs reaching the market offering similar efficacy, but suffering from the same oral delivery concerns. As such, the application of nanomedicine formulation approaches to currently available drugs is a viable option for optimizing oral drug delivery and maximizing treatment efficacy. This review focuses on the various delivery challenges encountered by psychotropic drugs, and the ability of nanomedicine formulation strategies to overcome these. Specifically, we critically review proof of concept in vitro and in vivo studies of nanoemulsions/microemulsions, solid lipid nanoparticles, dendrimers, polymeric micelles, nanoparticles of biodegradable polymers and nanosuspensions, and provide new insight into the various mechanisms for improved drug performance. The advantages and limitations of current oral nanomedicine approaches for psychotropic drugs are discussed, which will provide guidance for future research directions and assist in fostering the translation of such delivery systems to the clinical setting. Accordingly, emphasis has been placed on correlating the in vitro/in vivo performance of these nanomedicine approaches with their potential clinical outcomes and benefits for patients.

Parameters and characteristics governing cellular internalization and trans-barrier trafficking of nanostructures

Cellular internalization and trans-barrier transport of nanoparticles can be manipulated on the basis of the physicochemical and mechanical characteristics of nanoparticles. Research has shown that these factors significantly influence the uptake of nanoparticles. Dictating these characteristics allows for the control of the rate and extent of cellular uptake, as well as delivering the drug-loaded nanosystem intra-cellularly, which is imperative for drugs that require a specific cellular level to exert their effects. Additionally, physicochemical characteristics of the nanoparticles should be optimal for the nanosystem to bypass the natural restricting phenomena of the body and act therapeutically at the targeted site. The factors at the focal point of emerging smart nanomedicines include nanoparticle size, surface charge, shape, hydrophobicity, surface chemistry, and even protein and ligand conjugates. Hence, this review discusses the mechanism of internalization of nanoparticles and ideal nanoparticle characteristics that allow them to evade the biological barriers in order to achieve optimal cellular uptake in different organ systems. Identifying these parameters assists with the progression of nanomedicine as an outstanding vector of pharmaceuticals.

Targeting of eugenol-loaded solid lipid nanoparticles to the epidermal layer of human skin

Aim: The purpose of this study was to formulate carbopol hydrogels containing eugenol-loaded solid lipid nanoparticles (EG–SLNs) for epidermal targeting to treat fungal infections in skin. Materials & methods: EG–SLNs were incorporated into carbopol hydrogels and the physiochemical characteristics of EG–SLN in hydrogels were investigated by dynamic light scattering, transmission electron microscopy and atomic force microscopy. Rheological behavior and mechanical properties of hydrogels were also studied before and after incorporation of EG–SLNs. The epidermal-targeting ability of EG–SLN-enriched hydrogels was evaluated by estimation of eugenol in the epidermis of human cadaver skin. An occlusion (hydration) study was also performed to elucidate the mechanism of epidermal targeting of EG–SLN-enriched hydrogels. Results: The particle size (d90) and morphology of EG–SLNs were not significantly changed after incorporation into the hydrogel. EG–SLN of stearic acid-enriched hydrogels follow the Carreau model that describes pseudoplastic flow. The hydrogel containing EG–SLN of stearic acid and of Compritol® (Gattefose, Mumbai, India) showed significantly greater accumulation of eugenol in the epidermis (62.65 ± 4.35 and 52.86 ± 3.76 µg/cm2, respectively) than that of eugenol–hydroxypropyl-β–cyclodextrin complex in hydrogel (9.77 ± 1.16 µg/cm2) and almond oil solution of eugenol (3.45 ± 0.6 µg/cm2). The occlusion study demonstrated greater hydration of human cadaver skin treated with EG–SLN-enriched hydrogel compared with that of hydrogel and intact skin. Conclusion: Hydrogels containing EG–SLNs could be a promising formulation for epidermal targeting to treat fungal infections in skin.

Original submitted 26 March 2012; Revised submitted 29 January 2013

Targeting of diacerein loaded lipid nanoparticles to intra-articular cartilage using chondroitin sulfate as homing carrier for treatment of osteoarthritis in rats

Targeted delivery of antiosteoarthritic drug diacerein to articular tissue could be a major achievement and soluble polysaccharide chondroitin sulfate (ChS) may be a suitable agent for this. Therefore, diacerein loaded solid lipid nanoparticles modified with ChS (ChS-DC-SLN) were prepared for synergistic effect of these agents to combat multidimensional pathology of osteoarthritis (OA). Prepared formulation were of size range 396±2.7nm, showed extended release up to 16h and increased bioavailability of diacerein by 2.8 times. ChS-DC-SLN were evaluated for their effect on histopathology of femoro-tibial joint of rat knee and amount of ChS and rhein (an active metabolite of diacerein) at targeted site. Concentration of rhein was significantly higher in case of ChS-DC-SLN (7.8±1.23μg/ml) than that of drug dispersion (2.9±0.45μg/ml). It can be stated that ChS served as homing to articular cartilage for targeting of drug. Thus, ChS-DC-SLN have great potential to enhance the overall efficacy of treatment for OA.

FROM THE CLINICAL EDITOR

This study demonstrates the feasibility of targeted delivery of diacerein to articular tissue using soluble polysaccharide chondroitin sulfate as the targeting vector. This approach has the potential to significantly increase anti-arthritic drug concentration in joints without leading to systemic toxicity.

A comparison between use of spray and freeze drying techniques for preparation of solid self-microemulsifying formulation of valsartan and in vitro and in vivo evaluation

The objective of the present study was to develop self micro emulsifying formulation (SMEF) of valsartan to improve its oral bioavailability. The formulations were screened on the basis of solubility, stability, emulsification efficiency, particle size and zeta potential. The optimized liquid SMEF contains valsartan (20% w/w), Capmul MCM C8 (16% w/w), Tween 80 (42.66% w/w) and PEG 400 (21.33% w/w) as drug, oil, surfactant and co-surfactant, respectively. Further, Liquid SMEF was adsorbed on Aerosol 200 by spray and freeze drying methods in the ratio of 2 : 1 and transformed into free flowing powder. Both the optimized liquid and solid SMEF had the particle size <200 nm with rapid reconstitution properties. Both drying methods are equally capable for producing stable solid SMEF and immediate release of drug in in vitro and in vivo conditions. However, the solid SMEF produced by spray drying method showed high flowability and compressibility. The solid state characterization employing the FTIR, DSC and XRD studies indicated insignificant interaction of drug with lipid and adsorbed excipient. The relative bioavailability of solid SMEF was approximately 1.5 to 3.0 folds higher than marketed formulation and pure drug. Thus, the developed solid SMEF illustrates an alternative delivery of valsartan as compared to existing formulations with improved bioavailability.

Trastuzumab-conjugated vitamin E TPGS liposomes for sustained and targeted delivery of docetaxel

OBJECTIVES

In this study, the authors developed D-α-tocopheryl polyethylene glycol 1000 succinate (vitamin E TPGS or simply TPGS) liposomes and further conjugated them to trastuzumab for controlled and targeted delivery of docetaxel (DTX) as a model hydrophobic drug.

METHODS

DTX- or coumarin-6-loaded liposomes were prepared by solvent injection method and characterized for size and size distribution, surface charge, surface chemistry and drug encapsulation efficiency and drug release profile. SK-BR-3 cells were employed as an in vitro model for HER2-positive breast cancer and assessed for their cellular uptake and cytotoxicity of the two liposomal formulations. In vivo pharmacokinetics (PK) was investigated in Sprague-Dawley rats.

RESULTS

The IC(50) value was found to be 20.23 ± 1.95, 3.74 ± 0.98, 0.08 ± 0.4 μg/ml for the marketed preparation of DTX, TPGS liposomes and trastuzumab-conjugated TPGS liposomes, respectively after 24 h incubation with SK-BR-3 cells. In vivo PK experiments showed that i.v. administration of trastuzumab-conjugated liposomes achieved 1.9 and 10 times longer half-life, respectively than PEG-coated liposomes and DTX. The area under the curve (AUC) was increased by 3.47- and 1.728-fold, respectively.

CONCLUSION

The trastuzumab-conjugated vitamin E TPGS-coated liposomes showed greater potential for sustained and targeted chemotherapy in the treatment of HER2 overexpressing breast cancer.

Vitamin E TPGS coated liposomes enhanced cellular uptake and cytotoxicity of docetaxel in brain cancer cells

The aim of this work was to develop a drug delivery system of liposomes, which are coated with D-alpha-tocopheryl polyethylene glycol 1000 succinate (TPGS), a PEGylated vitamin E, with docetaxel as a model drug for enhanced treatment of brain tumour in comparison with the nude liposomes as well as with the so-called stealth liposomes, i.e. those coated with polyethylene glycol (PEG), which have been intensive investigated in the literature. Docetaxel or coumarin-6 loaded liposomes were prepared by the solvent injection method and characterized for their particle size, polydispersity, zeta potential and drug encapsulation efficiency. C6 glioma cells were employed as an in vitro model to access cellular uptake and cytotoxicity of the drug or coumarin-6 loaded liposomes. The particle size of the PEG or TPGS coated liposomes was ranged between 126 and 191nm. High-resolution field-emission transmission electron microscopy (FETEM) confirmed the coating of TPGS on the liposomes. The IC50 value, which is the drug concentration needed to kill 50% cells in a designated time period, was found to be 37.04±1.05, 31.04±0.75, 7.70±0.22, and 5.93±0.57μg/ml for the commercial Taxotere(®), the nude, PEG coated and TPGS coated liposomes, respectively after 24h culture with C6 glioma cells. The TPGS coated liposomes showed great advantages in vitro than the PEG coated liposomes.

Biodegradable Polymers Induce CD54 on THP-1 Cells in Skin Sensitization Test

Currently, nonanimal methods of skin sensitization testing for various chemicals, biodegradable polymers, and biomaterials are being developed in the hope of eliminating the use of animals. The human cell line activation test (h-CLAT) is a skin sensitization assessment that mimics the functions of dendritic cells (DCs). DCs are specialized antigen-presenting cells, and they interact with T cells and B cells to initiate immune responses. Phenotypic changes in DCs, such as the production of CD86 and CD54 and internalization of MHC class II molecules, have become focal points of the skin sensitization test. In this study, we used h-CLAT to assess the effects of biodegradable polymers. The results showed that several biodegradable polymers increased the expression of CD54, and the relative skin sensitizing abilities of biodegradable polymers were PLLG (75 : 25) < PLLC (40 : 60) < PLGA (50 : 50) < PCG (50 : 50). These results may contribute to the creation of new guidelines for the use of biodegradable polymers in scaffolds or allergenic hazards.

Effect of lipid matrix on repaglinide-loaded solid lipid nanoparticles for oral delivery

Aim: To study the effect of different types of lipid on the entrapment efficiency (EE) and physical stability of repaglinide (RG)-loaded solid lipid nanoparticles (SLNs). RG-loaded SLNs were prepared by modified solvent injection method using stearic acid (RSA), glycerol monosteratae (RGM), glyceryl behenate (RGB) and tristearin (RTS). Poloxamer F68 was used as a stabilizer. Results: SLNs were characterized by particle size, zeta-potential, EE, in vitro release, solid-state properties (differential scanning calorimetry, transmission electron microscopy and electron diffraction) and stability at 30°C/65% relative humidity for 3 months. The mean particle size and zeta-potential of RG-loaded SLNs prepared with different lipids in varying concentrations ranged from 150 to 355 nm and -21.04 ± 3.10 to -30.54 ± 2.76 mV, respectively. Conclusion: EE was found to vary with lipids in the following order: RSA < RGM < RGB < RTS. Tristearin-prepared SLNs showed a significant prolonged drug release up to 24 h. Differential scanning calorimetry and electron diffraction microphotograph results indicated that RG entrapped in the SLNs existed in an amorphous or molecular state. SLNs prepared with stearic acid, glycerol monostearate and glyceryl behenate after storage showed significant increases in particle size, polydispersity index and EE. The SLNs prepared with tristearin were stable.

Surface modifications of nanocarriers for effective intracellular delivery of anti-HIV drugs

A variety of nanocarriers such as bioconjugates, dendrimers, liposomes, and nanoparticles have been widely evaluated as potential targeted drug delivery systems. Passive targeting of nanoscale carriers is based on a size-flow-filtration phenomenon that is usually limited to tumors, the reticular endothelial system, and possibly lymph nodes (LNs). In fact, targeting the delivery of drugs to pivotal physiological sites such as the lymph nodes has emerged as a promising strategy in treating HIV disease. Ligands for specific cell surface receptors can be displayed on nanocarriers in order to achieve active targeting. The approach has been extensively used preclinically in cancer where certain receptors are over-expressed at various stages of the disease. Unfortunately, markers of HIV infection are lacking and latently infected cells do not show any signs of infection on their surface. However, the disease naturally targets only a few cell types. The HIV receptor CD4, coreceptors (CCR5 and CXCR4), and some receptors relatively specific for macrophages provide potentially valuable surface targets for drug delivery to all susceptible cells in patients infected by HIV. This review focuses on nanoscale targeting with an emphasis on surface modifications of drug delivery nanocarriers for active targeting. A number of related issues, including HIV biology, targets, pharmacokinetics, and intracellular fate as well as literature-cited examples of emerging surface-modified targeted carrier systems are discussed.

Stimulus-responsive targeted nanomicelles for effective cancer therapy

Emerging nanotechnology has already developed various innovative nanomedicines. Nanomicelles, self-assemblies of block copolymers, are promising nanomedicines for targeted drug delivery and imaging. Stimulus-responsive targeted nanomicelles are designed to release drugs based on stimuli such as pH, temperature, redox potential, magnetism and ultrasound. This article will focus on recent advancements in the design of stimulus-responsive targeted nanomicelles loaded with anticancer drugs to fulfill the challenges associated with cancer cells (e.g., multidrug resistance) for the effective treatment of cancer. The significant toxicity issues and a possible future perspective associated with nanomicelles are also discussed here.

PLGA nanoparticle formulations of risperidone: preparation and neuropharmacological evaluation

The aim of this work was to develop extended-release poly(d,l-lactide-co-glycolide) (PLGA) nanoparticles of risperidone and thermal-responsive in situ gel containing risperidone nanoparticles for parenteral (subcutaneous) delivery and to reduce the dose-dependent extrapyramidal side effects of risperidone. PLGA nanoparticles of risperidone were designed by nanoprecipitation method using polymeric stabilizer (Poloxamer 407). The prepared nanoparticles were characterized for particle size by photon correlation spectroscopy and atomic force microscopy. Poloxamer 407-based in situ gel containing PLGA nanoparticles of risperidone was prepared by modified cold method to control the initial rapid release from the nanoparticles. The in vivo efficacy (antipsychotic effect) of prepared formulations (nanoparticles and in situ gel containing nanoparticles) was studied by administering them subcutaneously to mice. Extrapyramidal side effects of the formulations were also studied. The particle size of the prepared nanoparticles ranged between 85 and 219 nm. About 89% to 95% drug encapsulation efficiency was achieved when risperidone was loaded at 1.7% to 8.3% by weight of the polymer. During in vivo studies prepared risperidone formulations showed an antipsychotic effect that was significantly prolonged over that of risperidone solution for up to 72 hours with fewer extrapyramidal side effects. The prolonged effect of risperidone was obtained from the risperidone formulations administered subcutaneously, and this may improve the treatment of psychotic disorders by dose reduction.

FROM THE CLINICAL EDITOR

The development of extended-release poly(d,l-lactide-co-glycolide) (PLGA) nanoparticles of risperidone is reported in this paper, along with the development of thermal-responsive in situ gel containing risperidone nanoparticles for parenteral (subcutaneous) delivery and to reduce the dose-dependent extrapyramidal side effects. In vivo studies showed a significantly prolonged antipsychotic effect with fewer extrapyramidal side effects.

Targeted nanomedicines: effective treatment modalities for cancer, AIDS and brain disorders

Novel technology in the nanomedicine field is expected to develop innovative products as targeted drug-delivery approaches. Targeted drug delivery of various drugs for the treatment of cancer, AIDS and brain disorders is the primary research area in which nanomedicines have a major role and need. This review is concerned with emerging targeted nanomedicines (polymeric nanoparticles, solid lipid nanoparticles, polymeric micelles, dendrimers, liposomes, gold nanoparticles and magnetic nanoparticles) and multifunctional carriers capable of combining targeted drug delivery and imaging (polymeric micelles, dendrimers and magnetic nanoparticles) in the field of pharmaceutical applications. The significant toxicity issues associated with these nanomedicines are also explored here.