Generation dependent safety and efficacy of folic acid conjugated dendrimer based anticancer drug formulations.

PURPOSE: Folate conjugated poly(propyleneimine) (PPI) dendrimer (FPPI) mediated anticancer therapy is being extensively discovered throughout the world. The present investigation was aimed at exploring the targeting potential of Melphalan loaded FPPI of different generations (MP-FPPI) for effective management of cancer. METHODS: The MP-FPPI formulations were compared for drug entrapment efficiency, in vitro release profile, toxicology, folate receptor blockage assay, cell uptake assay, stability studies, and in vivo studies. RESULTS: Upon increasing the dendrimer generation from fourth to fifth, the drug delivery parameters improved negligibly except the toxicological profile that improved exponentially. MTT assay in case of MCF-7 cells depicted the IC 50 values of 8 ± 0.15, 0.9 ± 0.02, 0.2 ± 0.01 and 10 ± 0.17 µM, respectively in case of MP-FPPI3, MP-FPPI4, MP-FPPI5, and free Melphalan suggesting folate based targeting to be the efficacious approach to kill cancer cells. The median survival time for tumor bearing mice treated with MP-FPPI3, MP-FPPI4, MP-FPPI5 and free drug was found to be 23, 59, 62 and 26 days, respectively. CONCLUSIONS: The study concludes fourth generation PPI dendrimer to be superior carrier for folate based tumor targeting compared to third and fifth generation based formulations. This work is expected to provide a significant clue in the selection of "dendrimer generation" for folate mediated cancer targeting therapy.

Glycyrrhizin Conjugated Dendrimer and Multi-Walled Carbon Nanotubes for Liver Specific Delivery of Doxorubicin.

The purpose of the present investigation was to investigate the drug targeting potential of glycyrrhizin (GL) conjugated dendrimers (GL-PPI) and multi walled carbon nanotubes (GL-MWCNTs) towards liver targeting of a model anti-cancer agent, doxorubicin (DOX). The synthesis was confirmed by FTIR, 1H-NMR and morphology analysis. Higher DOX loading was observed in case of GL-PPI-DOX and GL-MWCNT-DOX (43.02 ± 0.64% and 87.26 0.57%, respectively) than parent nanocarriers. GL attachment considerably reduced the haemolytic toxicity of DOX by 12.38 ± 1.05 and 7.30 ± 0.63% by GL-PPI-DOX and GL-MWCNT-DOX, respectively. MTT cytotoxicity studies, flow cytometry and cell morphology assessment was done in HepG2 cell. The IC50 of DOX was reduced from 4.19±0.05 µM to 2.0±0.01 and 2.7±0.03 µM, respectively by GL-PPI-DOX and GL-MWCNT-DOX, respectively. Flow cytometry and phase contrast microscopy confirmed GL conjugated formulations to be significantly dragging higher cancer cell number of cells in early apoptosis as well as in early apoptotic phase.

The development, characterization and in vivo anti-ovarian cancer activity of poly(propylene imine) (PPI)-antibody conjugates containing encapsulated paclitaxel.

Mesothelin, protein is frequently expressed in ovarian cancers. However, a full understanding of the biological functions of mesothelin is lacking. Here, we investigate the drug targeting potential of antibody conjugated modified half-generation poly (propylene imine) dendrimers i.e. immunodendrimers toward ovarian cancer with a model anti-cancer agent, paclitaxel (PTX). The synthesized plain 4.5G dendrimers as well as immunodendrimers were characterized by FT-IR, (1)H-NMR, TEM, and flow cytometry. Immunodendrimers exhibited considerably reduced hemolytic-, hepato- and nephrotoxicity. MTT cytotoxicity, flow cytometry and cell morphology studies were conducted in OVACAR-3 and A-431 cell. We demonstrate that PTX loaded immunodendrimers reduced the tumor volume significantly. The biodistribution studies further confirmed the targeting efficiency and higher biodistribution of immunodendrimers into the mesothelin protein expressing ovarian cancer cells. The results concluded that the developed immunodendrimers have potential to deliver significantly higher amount of the bioactive and have improved therapeutic outcome.

One platform comparison of solubilization potential of dendrimer with some solubilizing agents.

OBJECTIVE: To compare various solubilizing agents for their solubilizing propensity as well as effect of pH, concentration and time on solubility of a highly hydrophobic drug. MATERIALS AND METHODS: Dendrimers were synthesized by divergent method. Solubilization studies were carried out at different pH, concentration and time using Paclitaxel (PTX) as model drug. Hemolytic toxicity study was also performed. RESULTS: The solubility of PTX was increased with increasing concentration of solubilizing agents and the order of solubility enhancement effect of different solubilizing agents was found to be in the following order: fifth generation (5.0 G) poly(propylene imine) (PPI) dendrimers > ß-CD > Tween 80 > polyethylene glycol 6000. The solubility of PTX was found to be highest at pH 5.0 followed by pH 7.4 than pH 9.2. The result of hemolytic toxicity studies displayed that when these solubilizing agents are given in combination with PTX, the toxicity was found to be reduced as compare to plain drug. CONCLUSIONS: The solubility of PTX was found to be significantly higher in the presence of 5.0 G PPI dendrimers as compared to the other solubilizing agents. It is also concluded that 5.0 G PPI dendrimers not only enhanced the solubility of PTX many folds but also reduced the toxicity of PTX.

Enteric-coated epichlorohydrin crosslinked dextran microspheres for site-specific delivery to colon.

Enteric-coated epichlorohydrin crosslinked dextran microspheres containing 5-Fluorouracil (5-FU) for colon drug delivery was prepared by emulsification-crosslinking method. The formulation variables studied includes different molecular weights of dextran, volume of crosslinking agent, stirring speed, time and temperature. Dextran microspheres showed mean entrapment efficiencies ranging between 77 and 87% and mean particle size ranging between 10 and 25 µm. About 90% of drug was released from uncoated dextran microspheres within 8 h, suggesting the fast release and indicated the drug loaded in uncoated microspheres, released before they reached colon. Enteric coating (Eudragit-S-100 and Eudragit-L-100) of dextran microspheres was performed by oil-in-oil solvent evaporation method. The release study of 5-FU from coated dextran microspheres was complete retardation in simulated gastric fluid (pH 1.2) and once the coating layer of enteric polymer was dissolved at higher pH (7.4 and 6.8), a controlled release of the drug from the microspheres was observed. Further, the release of drug was found to be higher in the presence of dextranase and rat caecal contents, indicating the susceptibility of dextran microspheres to colonic enzymes. Organ distribution and pharmacokinetic study in albino rats was performed to establish the targeting potential of optimized formulation in the colon.

A Novel Neuroimaging Phenotype in the X-Linked Intellectual Disability with a Missense Mutation of CNKSR2 Gene.

Background: Mental retardation, X-linked, syndromic, Houge type (MRXSHG) is a form of mental retardation characterized by intellectual disability, speech and language impairments, and early-onset seizures. It has been recently recorded in Online Mendelian Inheritance in Man (OMIM), and only 10 cases have been reported in the literature so far. Objective: To highlight the novel neuroimaging findings in the pediatric X-linked intellectual disability with a missense mutation of connector enhancer of kinase suppressor of RAS2 (CNKSR2) gene. Material and Methods: We present a case of intellectual disability, refractory epilepsy, speech and language delay with subtle dysmorphism, and behavioral issues in an 11-year-old boy with novel neuroimaging findings in a CNKSR2 gene with missense mutation. Results: Brain MRI revealed involvement of the basal ganglia, predominantly the neostriatum, and along with the subependymal aspects with focal cavitations involving, especially the bilateral caudate heads. There was relative sparing of the globus pallidi and posterior putamina bilaterally. Whole-exome sequencing identified a hemizygous missense pathogenic variant in the CNKSR2 gene. The mother was found to be an asymptomatic carrier. Conclusion: This case report highlights the rare missense mutation in the CNKSR2 gene and abnormal neuroimaging findings, which further provide information about the phenotypic characteristics of X-linked syndromic intellectual disability.

Cancer targeting potential of some ligand-anchored poly(propylene imine) dendrimers: a comparison.

The present investigation was aimed at developing and comparing the cancer-targeting potential of ligand-anchored dendrimers. Folate-, dextran-, and galactose-anchored poly(propylene imine) dendrimers were synthesized and characterized. Dendritic formulations were evaluated for ex vivo cytotoxicity on HeLa and SiHa cell lines. Flow cytometry studies were performed on the HeLa cell line. An ex vivo MTT assay on HeLa cells indicated IC(50) values of 0.05, 0.2, 0.8, and 0.08 µM for folate, dextran, and galactose formulations, and for free paclitaxel (PTX), respectively. An analogous observation was carried out in SiHa cells, where IC(50) values of 0.6, 0.8, 10, and 6 µM were observed by folate, dextran, and galactose formulations, and free PTX, respectively. The outcome of the MTT assay and flow cytometry suggested the order of targeting potential of various ligands under investigation as folate > dextran > galactose. The outcome is deemed to be of scientific value and is believed to assist drug delivery scientists during selection of targeting ligands. FROM THE CLINICAL EDITOR: The cancer targeting potential of folate, dextran and galactose functionalized polypropyleneimine (PPI) dendrimers was studied by this group of investigators, reporting the order of targeting potential as folate > dextran > galactose.

Evaluation of solid lipid nanoparticles as carriers for delivery of hepatitis B surface antigen for vaccination using subcutaneous route.

PURPOSE: Solid lipid nanoparticles (SLN) have emerged as carriers for therapeutic peptides, proteins, antigens and bioactive molecules. We have explored the potential of SLN as carrier for Hepatitis B surface antigen (HBsAg) by surface modifications to enhance their loading efficiency and the cellular uptake, using subcutaneous route. METHODS: Four different formulations of SLN were prepared by solvent injection method and characterized for various physical properties: particle size, surface morphology, shape, zeta potential, polydispersity, X-ray diffraction analysis, release profile and entrapment efficiency. HBsAg loaded SLN were studied for their functional characteristics, in vitro cellular uptake and internalization studies by human dendritic cells, macrophages and fibroblasts, T cell proliferation and TH1/TH2 response. Humoral immune response elicited by subcutaneously administered HBsAg containing SLN formulations were studied in vivo in mice. RESULTS: Compared to soluble HBsAg; SLN, particularly the mannosylated formulation, showed better cellular uptake, lesser cytotoxicity and induction of greater TH1 type of immune response. They also showed better immunological potential by producing sustained antibody titer. CONCLUSION: Mannosylated SLN appears to be promising as carrier for vaccine delivery against hepatitis B as ascertained by in vitro and in vivo studies, however further investigations on humans are required to establish their potential as vaccines against hepatitis B infection.

Development and characterization of triazine based dendrimers for delivery of antitumor agent.

In the present study we developed the novel kind of triazine dendrimers by utilizing differential reactivity of the cyanuric chloride (triazine trichloride) which overcome the limitations associated with the others classes of dendrimers like toxicity, low yield, high synthesis cost etc. Triazine dendrimers were synthesized by divergent method using triazine trichloride as core and diethanolamine as branching unit to avoid the use of protecting group and functional group interconversion up to third generation. These hydroxyl terminated dendrimers were characterized by FTIR, 1HNMR, 13CNMR, ES mass spectroscopy, and by elemental analysis. The yield of pure G3 dendrimers was 63%. This novel dendrimers increases the aqueous solubility of hydrophobic drug Paclitaxel up to 0.562 mg/ml as well as showed control release behavior. Hemolytic and toxicology studies of this dendrimer in mice showed no adverse toxicity to the kidneys and the liver up to 200 mg/kg dose (i.p). Triazine being a hydrophobic compound, the core of this dendrimer is hydrophobic and supposed to easily incorporate the hydrophobic guest while presence of hydroxyl group on periphery increases its water solubility and reduces its toxicity; and thus it is useful in various fields like gene delivery, MRI contrasting agents, vaccines or as solubilization tool.

Comparative evaluation of hepatitis B surface antigen-loaded elastic liposomes and ethosomes for human dendritic cell uptake and immune response.

The aim of the present study was to evaluate two vesicular carrier systems, ethosomes and elastic liposomes loaded with hepatitis B surface antigen, for in vitro qualitative and quantitative uptake by human dendritic cells (DCs) and ability to stimulate T lymphocytes. Quantitative uptake of antigen-loaded carriers was documented by flow cytometry, and internalization of the systems by the DCs was studied using spectral bioimaging. Ability of antigen-pulsed DCs to stimulate autologous peripheral blood lymphocytes and levels of TH1/TH2 cytokines were also examined using flow cytometry. Both vesicular carrier systems as antigen delivery modules and DCs as antigen-presenting cells were able to generate a protective immune response. However, ethosomes were found to have higher internalizing ability and immunogenicity in comparison with elastic liposomes. These properties of ethosomes coupled with their skin-navigating potential, make it an attractive vehicle for development of a transcutaneous vaccine against hepatitis B in preference to elastic liposomes. FROM THE CLINICAL EDITOR: Two carrier systems for more potent vaccine administration - ethosomes and elastic liposomes loaded with hepatitis B surface antigen - are compared. Ethosomes demonstrated higher internalizing ability and immunogenicity. Due to their known skin-navigating potential, ethosomes may represent an attractive vehicle for development of a transcutaneous vaccine against hepatitis B.

Dendrimer nanocarriers as versatile vectors in gene delivery.

The successful delivery of nucleic acids to particular target sites is the challenge that is being addressed using a variety of viral and nonviral delivery systems, both of which have distinct advantages and disadvantages. Nonviral vectors offer the advantage of safety and flexibility over viral vectors, although they lack efficiency. Dendrimers are novel, three-dimensional polymers that have the ability to interact with various forms of nucleic acids such as plasmid DNA, antisense oligonucleotides, and RNA to form complexes that protect the nucleic acid from degradation. The interaction between the dendrimers and the nucleic acids is purely electrostatic where the cationic dendrimer condenses the anionic nucleic acids. Because cell membranes are negatively charged, the net positive charge of the dendrimer nucleic acid complex determines the transfection efficiency, although highly cationic systems are also cytotoxic. The nature of the dendrimer nucleic acid complex depends on various factors like stoichiometry, concentration of dendrimer-amines and nucleic acid-phosphates, as well as bulk solvent properties like pH, salt concentration, buffer strength, and dynamics of mixing. This article aims to review the role of dendrimers as novel gene delivery vectors both in vitro and in vivo. Dendrimer-based transfection reagents have become routine tools for in vitro transfection, but in vivo delivery of therapeutic nucleic acids remains a challenge. FROM THE CLINICAL EDITOR: This review discusses the role of dendrimers as novel gene delivery vectors both in vitro and in vivo. Dendrimer based transfection reagents have become routine tools for in vitro transfection but in vivo delivery of therapeutic nucleic acids remains a challenge.

Preparation, characterization and evaluation of targeting potential of amphotericin B-loaded engineered PLGA nanoparticles.

PURPOSE: The objective of present work was to develop a mannose-anchored, engineered nanoparticulate system for efficient delivery of amphotericin B to macrophages. Furthermore, the effect of spacer on macrophage targeting was also evaluated. METHODS: PLGA was conjugated to mannose via direct coupling (M-PLGA) and via PEG spacer (M-PEG-PLGA), and engineered PLGA nanoparticles (M-PNPs and M-PEG-PNPs) were prepared from respective conjugates. These prepared engineered PNPs were characterized for size, polydispersity index (PDI), surface charge, and drug entrapment efficiency (% DEE). Transmission electron microscopy (TEM) and atomic force microscopy (AFM) were employed to study the shape and surface morphology of engineered PNPs. Macrophage targeting was evaluated via cellular uptake, ex vivo antileishmanial activity and in vivo biodisposition pattern of engineered PNPs in macrophage-rich organs. RESULTS: The developed engineered PNPs were found to be of nanometric size (<200 nm) and to have low PDI (<0.162) and good entrapment efficiency (%DEE >53.0%). AFM and TEM revealed that both M-PNPs and M-PEG-PNPs had smooth surface and spherical topography. Engineered PNPs with spacer showed enhanced uptake, potential antileishmanial activity and higher disposition in macrophage-rich organs, suggesting improved macrophage targeting. CONCLUSIONS: The results suggest that engineering of nanoparticles could lead to development of efficient carrier for macrophage targeting.

Dendrimers as therapeutic agents: a systematic review.

OBJECTIVES: Dendrimers by virtue of their therapeutic value have recently generated enormous interest among biomedical scientists. This review describes the therapeutic prospects of the dendrimer system. KEY FINDINGS: Their bioactivity suggests them to be promising therapeutic agents, especially in wound healing, bone mineralisation, cartilage formation and tissue repair, and in topical treatments to prevent HIV transmission. Findings also demonstrate their potential as anti-prion, anti-Alzheimer's, anticoagulant, antidote, anti-inflammatory and anticancer agents. One of the dendrimer-based formulations with activity against herpes simplex virus (VivaGel from Starpharma) has successfully completed phase I clinical trials and is expected to be available on the market soon. SUMMARY: All reports cited in this review demonstrate the use of dendrimers as medical therapeutics in different ailments. The review focuses on the current state of therapeutic potential of the dendrimer system.

Carbohydrate-conjugated multiwalled carbon nanotubes: development and characterization.

This work presents a novel cascade of chemical functionalization of multiwalled carbon nanotubes (MWCNTs) through chemical modification by a carbohydrate, D-galactose. Galactose-conjugated or galactosylated MWCNTs were synthesized involving the sequential steps of carboxylation, acylation, amine modification, and finally, galactose conjugation. The modification of MWCNTs with galactose was investigated by elemental analysis, x-ray diffraction analysis, Fourier transform-infrared spectroscopy, Raman spectroscopy, and zeta potential measurements, at every sequential step of functionalization. Size and surface characteristics of chemically modified MWCNTs were monitored by transmission electron microscopy and scanning electron microscopy. That galactosylation improved the dispersibility of MWCNTs in aqueous solvents was confirmed by investigation of their dispersion characteristics at different pH values. Thus, the galactosylated MWCNTs as developed could be used for delivery of different bioactive(s) as well as active ligand (galactose)-based targeting to hepatic tissue. FROM THE CLINICAL EDITOR: This work presents a novel cascade of functionalization of multiwalled carbon nanotubes (MWCNTs) through chemical modification by a carbohydrate. Galactosylation improves the dispersibility of MWCNTs in aqueous solvents. The galactosylated MWCNTs could be used for delivery of different bioactive(s) as well as active ligand-based targeting to hepatic tissue.

Targeting potential and anti-HIV activity of lamivudine loaded mannosylated poly (propyleneimine) dendrimer.

T-lymphocytes, dendritic cells and macrophages are the target cells for HIV. The infected macrophages are considered as reservoirs for spreading the virus. Treatment of HIV infection therefore must reach these cells in addition to the organs like brain, liver and bone marrow. Lectin receptors, which act as molecular targets for sugar molecules, are found on the surface of these cells of the phagocytic system. The purpose of the present study is to investigate the targeting potential and anti HIV activity of lamivudine (3TC) loaded mannosylated fifth generation Poly (propyleneimine) dendrimers (MPPI). The entrapment efficiency of 3TC loaded MPPI and 5th generation poly(propyleneimine) dendrimer (PPI) were found to be 43.27+/-0.13% and 35.69+/-0.2% respectively. The in vitro drug release profile shows that while PPI releases the drug by 24 h, the MPPI slows down and hence prolongs the release up to 144 h (96.89+/-1.8% in case of MPPI). The results of in vitro ligand agglutination assay indicated that even after conjugation with PPI, mannose displayed binding specificity towards Con A. The subtoxic concentrations of free 3TC, blank PPI, blank MPPI, drug loaded PPI and drug loaded MPPI, determined on MT2 cells, were found to be 0.625, 0.039, 0.156, 0.039 and 0.156 nM/ml respectively. Significant increase in cellular uptake of 3TC was observed when MPPI was used, which was 21 and 8.3 times higher than that of free drug (p<0.001) and PPI (p<0.001) at 48 h respectively. Antiretroviral activity was determined using MT2 cell lines by estimating p24 antigen by ELISA. 3TC loaded PPI and MPPI formulations were found to possess higher anti-HIV activity at a concentration as low as 0.019 nM/ml, as compared to that of free drug, which was found to be extremely significant (p<0.001). The significantly higher anti-HIV activity of PPI and MPPI is due to the enhanced cellular uptake of 3TC in formulation as compared to that of free drug Results suggest that the proposed carrier hold potential to increase the efficacy and reduce the toxicity of antiretroviral therapy.

Folate and folate-PEG-PAMAM dendrimers: synthesis, characterization, and targeted anticancer drug delivery potential in tumor bearing mice.

Ligand-mediated targeting of drugs especially in anticancer drug delivery is an effective approach. Dendrimers, due to unique surface topologies, can be a choice in this context. In the present study, PAMAM (polyamidoamine) dendrimers up to fourth generation were synthesized and characterized through infrared (IR), nuclear magnetic resonance (NMR), electrospray ionization (ESI) mass spectrometric, and transmission electron microscopic (TEM) techniques. Primary amines present on the dendritic surface were conjugated through folic acid and folic acid-PEG (poly(ethylene glycol))-NHS (N-hydroxysuccinimide) conjugates. Tumor in mice was induced through the use of KB cell culture. Prepared dendritic conjugates were evaluated for the anticancer drug delivery potential using 5-FU (5-fluorouracil) in tumor-bearing mice. Approximately 31% of 5-FU was loaded in folate-PEG-dendritic conjugates. Results indicated that folate-PEG-dendrimer conjugate was significantly safe and effective in tumor targeting compared to a non-PEGylated formulation. Tailoring of dendrimers via PEG-folic acid reduced hemolytic toxicity, which led to a sustained drug release pattern as well as highest accumulation in the tumor area.

Clarithromycin- and omeprazole-containing gliadin nanoparticles for the treatment of Helicobacter pylori.

The aim of the present work was to prepare and evaluate the oral mucoadhesive sustained release nanoparticles of clarithromycin and omeprazole in order to improve patient compliance by improving its therapeutic effect and reducing its dose-related side effects. The clarithromycin- and omeprazole-containing gliadin nanoparticles were prepared by the desolvation method using Pluronic F-68 as a stabilizing agent. The results showed that this method is reproducible, easy, and leads to the efficient entrapment of drug as well as formation of spherical particles ranging from 400 to 650 nm. The maximum percentage of drug entrapment for clarithromycin and omeprazole was 81.7 +/- 2.2 and 73.7 +/- 3.9%, respectively, whereas the percentage of yield of the system was 85.1 +/- 1.9%. The sustained release behavior of gliadin nanoparticles was evaluated in phosphate-buffered saline (pH 7.4) and simulated gastric fluid (pH 1.2), at 37 +/- 1 degrees C. Their mucoadhesive properties were determined by in vitro and in vivo methods. In vitro antibacterial activity of the formulations was performed on isolated culture of Helicobacter pylori, which showed greater eradication effect of dual therapy entrapped formulations when compared with single therapy containing formulations and plain drugs.

Targeting of efavirenz loaded tuftsin conjugated poly(propyleneimine) dendrimers to HIV infected macrophages in vitro.

HIV infected macrophages are considered as reservoirs for spreading the virus in AIDS patients. Tuftsin not only binds specifically to the mononuclear phagocytic cells but also enhances their natural killer activity. The purpose of this study is to explore the targeting potential and anti-HIV activity of efavirenz (EFV) loaded, tuftsin conjugated 5th generation poly(propyleneimine) dendrimers (TuPPI) in vitro. Tuftsin was chemically conjugated to 5th generation poly(propyleneimine) dendrimers (PPI). The entrapment efficiency of PPI and TuPPI were found to be 37.43+/-0.3% and 49.31+/-0.33%, respectively. TuPPI was found to slow down and prolong the in vitro release of EFV upto 144h against PPI, which releases the drug completely within 24 h. TuPPI possessed negligible cytotoxicity as compared to that of PPI. The cellular uptake of TuPPI was found to be 34.5 times higher than that of the free drug in first 1 h and was significantly higher in HIV infected macrophages than that of uninfected cells. TuPPI was found to reduce the viral load by 99% at a concentration of 0.625 ng/ml, which is due to the enhanced cellular uptake, reduced toxicity and the inherent anti-HIV activity of TuPPI.

Radiolabeling, pharmacoscintigraphic evaluation and antiretroviral efficacy of stavudine loaded 99mTc labeled galactosylated liposomes.

The study was aimed to optimize radiolabeling with 99mTc, to determine the antiretroviral activity and to study the biodistribution of 99mTc labeled galactosylated liposomes loaded with stavudine. Liposomes were prepared using reverse-phase evaporation method followed by extrusion through 200nm polycarbonate membranes. The galactosylated liposomes were assessed for in vitro ligand-specific activity and the aggregation of galactosylated liposomes was found to increase as lectin concentration was increased from 5microg/ml to 30microg/ml. Free stavudine and stavudine loaded plain and galactosylated liposomes were radiolabeled with 99mTc by direct labeling method using stannous chloride as a reducing agent. Labeling method was optimized for stannous chloride quantity to achieve maximum labeling efficiency >95%. Antiretroviral activity was determined using human immunodeficiency virus-1 (HIV) infected MT2 cell line. A dose-dependent inhibition of p24 production was observed upon treatment of HIV-1 infected MT2 cells with stavudine loaded liposomes and galactosylated liposomes. Scintigraphic imaging and quantitative biodistribution of 99mTc labeled drug and liposomes showed that liposomal formulations were better taken up by the liver and spleen. Free drug solution was cleared from the blood. Further, a significantly higher (P<0.05) liver and spleen retention was observed over a period of 24h in case of galactosylated liposomes as compared to free drug and plain liposomes. Reduced uptake of the galactosylated liposomes in bone and higher and prolonged accumulation in mononuclear phagocyte system (MPS)-rich organs indicates the excellent potential of this formulation in the treatment of HIV infection.

Con-A conjugated mucoadhesive microspheres for the colonic delivery of diloxanide furoate.

The aim of the research work was to develop cyst-targeted novel concanavalin-A (Con-A) conjugated mucoadhesive microspheres of diloxanide furoate (DF) for the effective treatment of amoebiasis. Eudragit microspheres of DF were prepared using emulsification-solvent evaporation method. Formulations were characterized for particle size and size distribution, % drug entrapment, surface morphology and in vitro drug release in simulated gastrointestinal (GI) fluids. Eudragit microspheres of DF were conjugated with Con-A. IR spectroscopy and DSC were used to confirm successful conjugation of Con-A to Eudragit microspheres while Con-A conjugated microspheres were further characterized using the parameters of zeta potential, mucoadhesiveness to colonic mucosa and Con-A conjugation efficiency with microspheres. IR studies confirmed the attachment of Con-A with Eudragit microspheres. All the microsphere formulations showed good % drug entrapment (78+/-5%). Zeta potential of Eudragit microspheres and Con-A conjugated Eudragit microspheres were found to be 3.12+/-0.7mV and 16.12+/-0.5mV, respectively. Attachment of lectin to the Eudragit microspheres significantly increases the mucoadhesiveness and also controls the release of DF in simulated GI fluids. Gamma scintigraphy study suggested that Eudragit S100 coated gelatin capsule retarded the release of Con-A conjugated microspheres at low pH and released microspheres slowly at pH 7.4 in the colon.