Does 99mTc-tilmanocept, as next generation radiotracer, meet with the requirements for improved sentinel node imaging?

INTRODUCTION AND OBJECTIVES: To evaluate the migration of 99mTc-tilmanocept from the injection site (IS) as well as the uptake in sentinel nodes (SNs) and non-SNs for lymphatic mapping in patients with breast cancer and melanoma, scheduled for SN biopsy after interstitial tracer administration. MATERIALS AND METHODS: For 29 primary tumours in 28 patients (mean age: 62y, range: 45-81y) scheduled for SN biopsy planar images were acquired 10 and 120min after administration of 74MBq 99mTc-tilmanocept, in order to evaluate lymphatic drainage as well as uptake ratios between injection site (IS), SN and non-SN. SPECT-CT was performed immediately after delayed planar images to enable anatomical lymph node localization. RESULTS: SNs were visualized in all patients (100%) with drainage to 34 basins. Uptake in non-SNs was perceived in 16 basins (47%). Number of SNs was concordant between early and delayed images in all basins excepting five (86%). In 24 patients tracer migrated to one lymph node basin (LNB), in three to 2 and in one to 4. When IS was included (N=29) on image, IS/SN ratio could be measured per LNB. The IS/SN ratio at 2h compared to 15min decreased with an average of 66% (range: 15-96%). SN/non-SN 2h ratio in LNBs with visible non-SNs averaged 6.6 (range: 2.3-15.6). In 9 patients with two SNs SN1/SN2 ratio averaged 1.9 on delayed images. At histopathology, SNs were found to be tumour positive in 7 basins (20%). CONCLUSION: 99mTc-tilmanocept appears to meet the requirements for improved SN imaging in breast cancer and melanoma on the basis of early and persistent SN visualization frequently accompanied by no or markedly less non-SN uptake. This is associated to rapid migration from the injection site together with increasing SN uptake and retention as expressed by decreasing IS/SN and persistently high SN/non-SN ratios. Further head-to-head comparison of 99mTc-tilmanocept with standard SN radiotracers in larger series of patients is necessary.

Formulation development and in-vitro evaluation of gastroretentive drug delivery system of loxoprofen sodium: A natural excipients based approach.

The limitations of conventional type delivery systems to retain drug (s) in the stomach has resulted in the development of novel gastroretentive drug delivery system. We developed single-layer effervescent floating tablets of loxoprofen sodium for prolong delivery in the stomach using natural polymers xanthan gum, guar gum and semisynthetic polymer HPMCK4M. All the formulations (F1-F9) were developed by varying concentrations of xanthan gum and HPMCK4M while guar gum concentration was kept constant. Two gas generating agent (s) incorporated were sodium bicarbonate and citric acid. All compendial pre and post-compression tests results were in the acceptable limits. FTIR analysis confirmed drug-polymer compatibility. The in-vitro drug release in simulated conditions i.e., 0.1 N HCl for 12 h revealed orderly increase in total floating time, i.e., less than 6 h for F1 over 12 h for F9. Formulations F1 to F4 were not capable to retard drug release up to 12 h, whereas F5-F7 for 12 h, while F8 and F9 for more than 12 h. Data fitting in various kinetic models showed that drug release best fit in first order kinetic model and F9 in zero order. Based on results data, F7 was the best among all.

Delivering Antisense Oligonucleotides across the Blood-Brain Barrier by Tumor Cell-Derived Small Apoptotic Bodies.

The blood-brain barrier (BBB) is the most restrictive and complicated barrier that keeps most biomolecules and drugs from the brain. An efficient brain delivery strategy is urgently needed for the treatment of brain diseases. Based on the studies of brain-targeting extracellular vesicles (EVs), the potential of using small apoptotic bodies (sABs) from brain metastatic cancer cells for brain-targeting drug delivery is explored. It is found that anti-TNF-α antisense oligonucleotide (ASO) combined with cationic konjac glucomannan (cKGM) can be successfully loaded into sABs via a transfection/apoptosis induction process and that the sABs generated by B16F10 cells have an extraordinarily high brain delivery efficiency. Further studies suggest that ASO-loaded sABs (sCABs) are transcytosed by b. End3 (brain microvascular endothelial cells, BMECs) to penetrate the BBB, which is mediated by CD44v6, and eventually taken up by microglial cells in the brain. In a Parkinson's disease (PD) mouse model, sCABs dramatically ameliorate PD symptoms via the anti-inflammatory effect of ASO. This study suggests that sABs from brain metastatic cancer cells are excellent carriers for brain-targeted delivery, as they have not only an extraordinary delivery efficiency but also a much higher scale-up production potential than other EVs.

Carboxymethyl fenugreek galactomannan-g-poly(N-isopropylacrylamide-co-N,N'-methylene-bis-acrylamide)-clay based pH/temperature-responsive nanocomposites as drug-carriers.

The current study dealt with the synthesis and characterization of carboxymethyl fenugreek galactomannang-g-poly(N-isopropylacrylamide-co-N,N'-methylene-bis-acrylamide)-bentonite [CFG-g-P(NIPA-co-MBA)-BEN] based nanocomposites (NCs) as erlotinib (ERL)-delivery devices for lung cancer cells to suppress excessive cell proliferation. The blank NCs exhibited outstanding biodegradability and pH/temperature-dependent swelling profiles, which were significantly influenced by their BEN contents (0-20%). The molar mass (M¯c) between the crosslinks of these NCs was declined with temperature. The composite architecture of these scaffolds was confirmed by XRD, FTIR, TGA, DSC and SEM analyses. The corresponding ERL-loaded matrices (F-1-F-3) portrayed outstanding drug encapsulation efficiency (DEE, 93-100%) with zeta potential between -8 and -16 mV and diameter between 615 and 1258 nm. These formulations demonstrated sustained ERL elution profiles (Q8h, 62-98%) with an initial burst release of drug. The drug dissolution pattern of the optimized matrices (F-3) obeyed first-order kinetic model and was driven by Fickian diffusion. The mucin adsorption behavior of F-3 was best fitted to Freudlich isotherms. The ERL-loaded formulation suppressed A549 cell proliferation and promoted apoptosis to a greater extent than the pristine drug, as detected by cellular uptake analysis, MTT cytotoxicity test and AO/EB staining assay.

Controlled release of silver ions from AgNPs using a hydrogel based on konjac glucomannan and chitosan for infected wounds.

Konjac glucomannan is a biocompatible polysaccharide with high medicinal potential. In this study, we prepared a hydrogel using an optimized crosslinking konjac glucomannan and chitosan. Silver nanoparticles (AgNPs) were incorporated into the hydrogel to enhance its antimicrobial property. This nanocomposite hydrogel could absorb wound exudates due to its swelling ability, and showed self-healing property that enabled structure stability. Moreover, as a carrier, the hydrogel could modulate the release of silver ions burst, thereby reducing AgNPs cytotoxicity. Rats models with infected skin defects were used to assess wound healing. The results indicated that AgNPs hydrogels dressing could promote wound healing and reduce inflammatory response, exhibiting great clinical application potentials.

Poly(hydroxybutyrate-co-hydroxyvalerate) microparticles embedded in κ-carrageenan/locust bean gum hydrogel as a dual drug delivery carrier.

A novel composite hydrogel was prepared as a dual drug delivery carrier. Poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) microparticles were prepared to encapsulate simultaneously ketoprofen and mupirocin, as hydrophobic drug models. These microparticles were embedded in a physically crosslinked hydrogel of κ-carrageenan/locust bean gum. This composite hydrogel showed for both drugs a slower release than the obtained release from microparticles and hydrogel separately. The release of both drugs was observed during a period of 7 days at 37 °C. Different kinetic models were analyzed and the results indicated the best fitting to a Higuchi model suggesting that the release was mostly controlled by diffusion. Also, the drug loaded microparticles were spherical with average mean particle size of 1.0 µm, mesoporous, and distributed homogeneously in the hydrogel. The composite hydrogel showed a thermosensitive swelling behavior reaching 183% of swelling ratio at 37 °C. The composite hydrogel showed the elastic component to be higher than the viscous component, indicating characteristics of a strong hydrogel. The biocompatibility was evaluated with in vitro cytotoxicity assays and the results indicated that this composite hydrogel could be considered as a potential biomaterial for dual drug delivery, mainly for wound healing applications.

Preparation of 99mTc-Labeled Mannan-S-Cysteine and Effect of Molecular Size of Mannan on Its Biodistribution.

Macrophage mannose receptor (MMR/CD206) is a promising target for the detection and identification of sentinel lymph node (SLN). MMR-targeting probes have been developed using mannosylated dextran, however, impairment of efficient targeting of SLN was often caused because of retention of injection site in which macrophages and dendritic cells exist. In this study, we prepared new MMR-targeting probes from yeast mannan (85 kDa), and its bioditribution was investigated. In-vivo evaluation showed that 11.9% of injected dose of 99mTc-labeled mannan-S-cysteines (99mTc-MSCs) was accumulated in popliteal lymph node (the SLN in this model), however, significant level of radioactivity (approximately 80%) was remained in injection site. Interestingly, 99mTc-labeled low molecular weight mannan-S-cysteine mannan (99mTc-LSC) prepared from 50 and 25 kDa mannan showed a decreased specific accumulation of 99mTc-LSC in the popliteal lymph node, while the radioactivity at the injection site remained unchanged. These results suggest that the molecular size, or nature/shape of the sugar chain is important for the specific accumulation of 99mTc-MSC in popliteal lymph node.

Complex coacervation of carboxymethyl konjac glucomannan and chitosan and coacervate characterization.

Carboxymethyl konjac glucomannan (CMKGM) shows potential in the construction of colon-targeted delivery systems through electrostatic interaction-based techniques. Its coacervation with chitosan (CHI) was investigated as a function of degree of substitution (DS). CMKGMs displayed the same optimum coacervation conditions of pH 6.5 and mass ratio 1:1 with CHI, but the coacervate yield was positively related to their DS. The coacervation was weakened by the presence of NaCl, but was not affected in temperatures 25-75 °C and total biopolymer concentrations 0.05-0.15% (w/v). Both electrostatic interaction and hydrogen bonding were involved in the coacervation and a higher DS contributed a denser network structure, a smaller particle size, and greater elasticity. The coacervates maintained their structures in simulated gastrointestinal fluids, but could be degraded by the ß-mannanase in simulated colonic fluid. Hence, CMKGMs could be used in colon-targeted and enzyme-triggered delivery systems and the delivery performance could be tailored by varying their DS.

In-vitro and In-vivo Pharmacokinetic Evaluation of Guar Gum-Eudragit® S100 Based Colon-targeted Spheroids of Sulfasalazine Co-administered with Probiotics.

BACKGROUND: Polysaccharide based delivery systems have been successfully used to target drugs to colon. In some recent reports, the superiority of concomitant administration of probiotics with such systems has been established. However, the pharmacokinetics of such symbiotic therapy remain unexplored hitherto. METHODS: This study deciphers the pharmacokinetic parameters of guar gum based colon targeted spheroids of sulfasalazine with co-administration of probiotics in experimental rats. Thirty rats were divided into five groups using Latin square design. These were subjected to treatment with delayed release formulation, uncoated spheroids, coated spheroid and coated spheroids along with probiotics. RESULTS: In case of delayed release formulation, negligible presence of sulfasalazine in plasma was observed in first 2h, followed by significant increase in sulfasalazine concentration after 3h. Higher plasma concentrations of sulfasalazine were detected for uncoated spheroids with and without probiotics. Negligible release of drug upto 5h and delayed Tmax in case of guar-gum coated sulfasalazine spheroids with or without probiotics clearly indicated successful formulation of colon targeted spheroids. Further, for coated spheroids (both with and without probiotics), the value of Tmax is found to be significantly higher than those with the other treatments. CONCLUSION: Colon targeted spheroids were therefore, found to reduce absorption of drug which, in turn, is expected to reduce the side effects as only local action in colon is required for treatment of colitis. This is the first report on pharmacokinetic study of a colon targeted delivery system co-administered with probiotics.

Faster in vivo clearance of human embryonic kidney than Chinese hamster ovary cell derived protein: Role of glycan mediated clearance.

This investigation used in vivo and in vitro tools to study pharmacokinetics and glycosylation of two monomeric antibodies produced either transiently by HEK293 cells or stably by Chinese hamster ovary cells, and demonstrated that higher in vivo clearance of human embryonic kidney antibody was due to higher glycosylation, thus higher mannose receptor mediated uptake.

Locust bean gum safety in neonates and young infants: an integrated review of the toxicological database and clinical evidence.

Locust bean gum (LBG) is a galactomannan polysaccharide used as thickener in infant formulas with the therapeutic aim to treat uncomplicated gastroesophageal reflux (GER). Since its use in young infants below 12weeks of age is not explicitly covered by the current scientific concept of the derivation of health based guidance values, the present integrated safety review aimed to compile all the relevant preclinical toxicological studies and to combine them with substantial evidence gathered from the clinical paediatric use as part of the weight of evidence supporting the safety in young infants below 12weeks of age. LBG was demonstrated to have very low toxicity in preclinical studies mainly resulting from its indigestible nature leading to negligible systemic bioavailability and only possibly influencing tolerance. A standard therapeutic level of 0.5g/100mL in thickened infant formula is shown to confer a sufficiently protective Margin of Safety. LBG was not associated with any adverse toxic or nutritional effects in healthy term infants, while there are limited case-reports of possible adverse effects in preterms receiving the thickener inappropriately. Altogether, it can be concluded that LBG is safe for its intended therapeutic use in term-born infants to treat uncomplicated regurgitation from birth onwards.

Atherosclerotic imaging using 4 types of superparamagnetic iron oxides: new possibilities for mannan-coated particles.

PURPOSE: We used magnetic resonance imaging (MRI) and histologic techniques to compare the uptake by the rabbit atherosclerotic wall of 4 types of superparamagnetic iron oxide (SPIO) particles, i.e. SPIO, mannan-coated SPIO (M-SPIO), ultrasmall SPIO (USPIO), and mannan-coated USPIO (M-USPIO). MATERIALS AND METHODS: All experimental protocols were approved by our institutional animal experimentation committee. We intravenously injected 12 Watanabe heritable hyperlipidemic rabbits with one of the 4 types of SPIO (0.8 mmol Fe/kg). Two other rabbits served as the control. The rabbits underwent in vivo contrast-enhanced magnetic resonance angiography (MRA) before- and 5 days after these injections; excised aortae were subjected to in vitro MRI. In the in vivo and in vitro studies we assessed the signal intensity of the vessels at identical regions of interest (ROI) and calculated the signal-to-noise ratio (SNR). For histologic assessment we evaluated the iron-positive regions in Prussian blue-stained specimens. RESULTS: There were significant differences in iron-positive regions where M-USPIO>USPIO, M-SPIO>SPIO, USPIO>SPIO (p<0.05) but not between M-USPIO and M-SPIO. The difference between the pre- and post-injection SNR was significantly greater in rabbits treated with M-USPIO than USPIO and in rabbits injected with M-SPIO than SPIO (p<0.05). On in vitro MRI scans SNR tended to be lower in M-USPIO- and M-SPIO- than USPIO- and SPIO-treated rabbits (p<0.1). CONCLUSION: Histologic and imaging analysis showed that mannan-coated SPIO and USPIO particles were taken up more readily by the atherosclerotic rabbit wall than uncoated SPIO and USPIO.

Hydrolyzed galactomannan-modified nanoparticles and flower-like polymeric micelles for the active targeting of rifampicin to macrophages.

Inhalable nanocarriers that are uptaken by macrophages represent an appealing approach for the targeting of antibiotics to the tuberculosis reservoir. In the present work, we report on the development of rifampicin (RIF)-loaded nanoparticles and flower-like polymeric micelles surface-modified with hydrolyzed galatomannan (GalM-h), a polysaccharide of mannose and galactose, two sugars that are recognized by lectin-like receptors. Initially, pure or GalM-h-associated chitosan nanoparticles (NPs) were produced by ionotropic gelation. Despite the composition, NPs displayed positive zeta potential values between +18.0 and +24.5 mV and a size ranging between 263 and 340 nm. In addition, RIF payloads were approximately 1.0% w/w. To increase the encapsulation efficiency, a more complex nanocarrier based on poly(epsilon-caprolactone)-b-poly(ethylene-glycol)-b-poly(epsilon-caprolactone) flower-like polymeric micelles (PMs) coated with chitosan or GalM-h/chitosan were engineered. These polymeric micelles displayed a bimodal size distribution with a positive zeta potential between +6.7 and +8.1 mV. More importantly, the drug encapsulation capacity was increased 12.9-fold with respect to the NPs. An agglutination assay with concanavalin A confirmed the presence of GalM-h on the surface. Qualitative uptake studies by fluorescence microscopy revealed that GalM-h-modified systems were taken-up by RAW 264.7 murine macrophages. Finally, the intracellular/cell associated levels of RIF following the incubation of cells with free or encapsulated drug indicated that while chitosan hinders the uptake, GalM-h leads to a significant increase of the intracellular concentration.

Preparation and characterization of cross-linked guar gum microspheres: optimization using factorial design.

In the present work cross-linked guar gum microspheres were prepared for colon specific delivery of ornidazole. Development and optimization of guar gum microspheres for colonic drug delivery was carried out using a 2(4) factorial design based on four independent variables. Microspheres were prepared by emulsification method using glutaraldehyde as cross-linking agent. Morphology and surface characteristics of the formulations were determined by scanning electron microscopy. Particle size of the guar gum microspheres was determined by particle size analyzer. In vitro drug-release studies were performed in conditions simulating stomach-to-colon transit in the presence and absence of rat cecal contents. Only a small fraction of drug was released at acidic pH; however, the release of drug was found to be higher in the presence of rat cecal contents, indicating the susceptibility of guar gum matrix to colonic enzymes released from rat cecal contents. The significance of differences was evaluated by analysis of variance (ANOVA). Differences were considered statistically significant at p<0.05.

pH-enzyme di-dependent chronotherapeutic drug delivery system of theophylline for nocturnal asthma.

The purpose of this research work was to develop and evaluate a chronotherapeutic based colon-targeted drug delivery system of theophylline (THEO) exploiting pH-enzyme sensitive property for the prevention of episodic attack of asthma in early morning. Guar gum microspheres of theophylline were prepared by emulsification technique. Coating of microspheres was performed using solvent evaporation method with pH sensitive Eudragit(®) polymers. The particle size and surface morphology, entrapment efficiency and degree of swelling of microspheres were examined. The in vitro drug release studies were performed in pH progression medium and also in the presence of 2% rat caecal content. Theophylline was efficiently microencapsulated in guar gum microspheres at different polymer concentrations (1-4%). Fourier transform infrared (FT-IR)-spectroscopy confirmed the intermolecular interactions between guar gum and glutaraldehyde. Coating of guar gum microspheres by Eudragit led to decelerate the in vitro drug release of THEO. Moreover in vitro drug release studies also performed with 2% rat caecal content showed marked increment in drug release. The controlled release of THEO after a lag time was achieved with developed formulation for chronotherapeutic delivery. The pH dependent solubility behavior of Eudragit and gelling properties of guar gum are found to be responsible for delaying the release.

Fast 18F labeling of a near-infrared fluorophore enables positron emission tomography and optical imaging of sentinel lymph nodes.

We combine a novel boronate trap for F(-) with a near-infrared fluorophore into a single molecule. Attachment to targeting ligands enables localization by positron emission tomography (PET) and near-infrared fluorescence (NIRF). Our first application of this generic tag is to label Lymphoseek (tilmanocept), an agent designed for receptor-specific sentinel lymph node (SLN) mapping. The new conjugate incorporates (18)F(-) in a single, aqueous step, targets mouse SLN rapidly (1 h) with reduced distal lymph node accumulation, permits PET or scintigraphic imaging of SLN, and enables NIRF-guided excision and histological verification even after (18)F decay. This embodiment is superior to current SLN mapping agents such as nontargeted [(99m)Tc]sulfur colloids and Isosulfan Blue, as well as the phase III targeted ligand [(99m)Tc]SPECT Lymphoseek counterpart, species that are visible by SPECT or visible absorbance separately. Facile incorporation of (18)F into a NIRF probe should promote many synergistic PET and NIRF combinations.

Sentinel lymph node accumulation of Lymphoseek and Tc-99m-sulfur colloid using a "2-day" protocol.

Lymphoseek is a receptor-binding radiopharmaceutical specifically designed for sentinel lymph node (SLN) mapping. We conducted a clinical trial which measured the injection site clearance and sentinel lymph node accumulation after a single intradermal injection of Lymphoseek or unfiltered [(99m)Tc]sulfur colloid (TcSC) using a "2-day" protocol for SLN mapping of breast cancer. Eleven patients with breast cancer participated in this study. Five patients received an intradermal administration of 1.0 nmol of (99m)Tc-labeled Lymphoseek; SLN mapping was performed on four subjects within 19 to 27 h. Six subjects received an intradermal administration of TcSC; SLN mapping was performed on five subjects within 18 to 26 h. Lymphoseek exhibited a significantly (P<.001) faster injection site clearance than TcSC. The mean Lymphoseek clearance half-time was 2.18+/-1.09 h compared to 57.4+/-92.8 h for TcSC. The mean sentinel lymph node uptake of Lymphoseek (1.5+/-1.7%) and TcSC (3.5+/-3.1%) was statistically equivalent (P=.213). When an intradermal injection is employed, Lymphoseek demonstrated faster injection site clearance than unfiltered [(99m)Tc]sulfur colloid and persistent SLN accumulation for at least 24 h.

[Studies on in vivo release of berberine hydrochloride from carboxymethyl konjac glucomannan pellets in rats].

OBJECTIVE: To observe the absorption and concentration of berberine hydrochloride (BH) in gastric, entric, colonic tissue after intragastric administration of BH-containing carboxymethyl konjac glucomannan pellets for evaluating colon-specific drug delivery characteristics of the pellets. METHOD: BH-containing carboxymethyl konjac glucomannan pellets (pellets group) and BH-containing carboxymethyl cellulose suspension (control group) were intragastric administrated to rats at the dose of 50 mg x kg(-1), respectively. A high performance liquid chromatography method determinated BH concentration in rat plasma and tissue. Drug delivery index (DDI) was calculated. RESULT: The range of BH in plasma and tissue in rats were 0.025 2-2.52 mg x L(-1) (r = 0.999 2) and 0.126-25.22 mg x L(-1) (R > 0.99),respectively. The detection of BH in plasma and tissue were 10 microg x L(-1) and 8 microg x L(-1), respectively. The area under the curve (AUC(0 --> infinity)) in the plasma samples of pellets group was 0.477 times that of the control group; in the gastric, entric, colonic tissue, the AUC(0 --> infinity) of pellets group was as much as 0.187, 0.228, 2.00 times that of the control group, respectively. The DDI of the pellets was 0.392 4, 0.478 6, 4.193 in the gastric, entric, colonic tissue of the rat, respectively. CONCLUSION: Carboxymethyl konjac glucomannan pellets may be a useful carrier of BH for colon-specific delivery.

Sentinel lymph node mapping of breast cancer via intradermal administration of Lymphoseek.

Lymphoseek is a molecular imaging agent specifically designed for sentinel lymph node (SLN) mapping. We conducted a Phase I trial which measured the injection site clearance and SLN accumulation after a single intra dermal injection of Lymphoseek or [99mTc]sulfur colloid protocol. Ten patients with breast cancer participated in this study. Five patients received an intradermal administration of 1.0 nmol of 99mTc-labeled Lymphoseek and five patients received an intradermal administration of filtered [99mTc]sulfur colloid (fTcSC). Lymphoseek exhibited a significantly (P<.001) faster injection site clearance than fTcSC. The mean Lymphoseek clearance half-time was 2.61+/-0.72 h compared to 24.1+/-17.7 h for fTcSC. The mean SLN uptake of Lymphoseek (1.1+/-.5%) and fTcSC (2.5+/-4.9%) was statistically equivalent (P=.28). When an intra dermal injection was employed, Lymphoseek demonstrated faster injection site clearance than fTcSC.