Acylated chitosan anchored paclitaxel loaded liposomes: Pharmacokinetic and biodistribution study in Ehrlich ascites tumor bearing mice.

Acylated chitosan (Myristoyl and Octanoyl) coated paclitaxel-loaded liposomal formulation was developed with an aim to overcome the cremophor EL related toxicities. They were evaluated for drug entrapment, in vitro drug release, and cytotoxicity and cell uptake behavior using A549 cells. The 99mTc radio-labeled formulations were also evaluated in vivo in Ehrlich Ascites Tumor (EAT) bearing mice for biodistribution and tumor uptake. The mean particle size of both coated and uncoated liposomal formulations was found to be in the range of 180-200 nm with high drug entrapment efficiency (>90% in case of uncoated liposomes and 80 ±â€¯5% in case of coated liposomes). The uncoated liposomes displayed negative zeta potential (-10.5 ±â€¯4.9 mV) whereas coated liposomes displayed positive zeta potential in the range of +21 to +27 mV. Slower drug release was observed in case of liposomes coated with acylated chitosans as compared to uncoated and native chitosan coated liposomes. All liposomal formulations were found less cytotoxic than paclitaxel injection (Celtax™, Celon Labs, India). In vitro cell uptake and intracellular distribution studies confirmed the cytosolic delivery of uncoated and coated liposomes. The myristoyl chitosan coated liposomal system (LMC) exhibited improved pharmacokinetic, biodistribution and tumor uptake characteristics over other formulations. These obtained results confirmed the potential application of acylated chitosn coated liposomal delivery systems (LMC) in tumor targeting of paclitaxel and other drugs.

Anxiolytic actions of Nardostachys jatamansi via GABA benzodiazepine channel complex mechanism and its biodistribution studies.

Nardostachys jatamansi has profound applications against pharmacological interventions and is categorized as a hypno-sedative drug according to Ayurveda. In the present study probable mechanism of anxiolytic action of Nardostachys jatamansi extract (NJE) was studied using behavioral anxiolytic tests (Elevated plus maze, Open field test, Light dark box test, and Vogel's conflict test) in mice. Mice were treated orally with NJE (250 mg/kg) for 3, 7 and 14 days or diazepam (1 mg/kg) followed by behavioral assessment and estimation of monoamine neurotransmitters, GABA, and antioxidant enzymes. Treatment of mice for 7 days caused an increase in time spent in open arms in elevated plus maze, number of line crossings in open field test, increased time spent in lit compartment of light-dark box test, an increase in number of licks made and shocks accepted in Vogel's conflict test, with results comparable to diazepam and this treatment also caused a significant increase in monoamine neurotransmitters and GABA in brain and tissue antioxidant parameters. Co-treatment of NJE with flumazenil (GABA-benzodiazepine antagonist; 0.5 mg/kg i.p) or picrotoxin (GABAA gated chloride channel blocker; 1 mg/kg i.p) caused a blockage/antagonised anxiolytic actions of NJE by causing a significant reduction in time spent in open arms of elevated plus maze, an decrease in number of line crossing in open field test and also number of shocks and licks accepted in Vogel's conflict test. Further, NJE was radiolabelled with technetium99m at their hydroxyl groups following which purity as well as in vivo and in vitro stability of radiolabelled formulations was evaluated. The blood kinetics and in vivo bio-distribution studies were carried out in rabbits and mice respectively. Labeled formulation was found to be stable in vitro (96 to 93% stability) and in vivo (96 to 92% stability). The labeled compound was cleared rapidly from blood (within 24 h) and accumulated majorly in kidneys (11.65 ± 1.33), liver (6.07 ± 0.94), and blood (4.03 ± 0.63) after 1 h. However, a small amount was observed in brain (0.1 ± 0.02) probably because of its inability to cross blood-brain barrier. These results highlight biodistribution pattern of NJE, and also indicated that a 7-day treatment with NJE produced significant anxiolytic effects in mice and also a significant increase in brain monoamine and GABA neurotransmitter levels and suggests that anxiolytic effects of NJE are primarily and plausibly mediated by activating GABAergic receptor complex.

Preclinical Study of Ibuprofen Loaded Transnasal Mucoadhesive Microemulsion for Neuroprotective Effect in MPTP Mice Model.

Ibuprofen, a non-steroidal anti-inflammatory drug (NSAID), showed very promising neuroprotection action, but it suffers from high first pass metabolism and limited ability to cross blood brain barrier. Severe gastric toxicity following oral administration further limits its utility. Hence, the aim of this study was to investigate whether ibuprofen loaded mucoadhesive microemulsion (MMEI) could enhance the brain uptake and could also protect the dopaminergic neurons from MPTP-mediated neural inflammation. In this work, ibuprofen loaded polycarbophil based mucoadhesive microemulsion (MMEI) was developed by using response surface methodology (RSM). Male C57BL/6 mice were intranasally given 2.86 mg ibuprofen/kg/day for 2 consecutive weeks, which were pre-treated with four MPTP injections (20 mg/kg of body weight) at 2 h interval by intraperitoneal route and immunohistochemistry was performed. Globule size of optimal MMEI was 46.73 nm ± 3.11 with PdI value as 0.201 ± 0.19. Histological observation showed that optimal MMEI was biocompatible and suitable for nasal application. The result showed very significant effect (p < 0.05) of all three independent variables on the responses of the developed MMEI. Noticeable improvement in motor performance with spontaneous behavior was observed. TH neurons count in substantia nigra with the density of striatal dopaminergic nerve terminals after MMEI administration. Results of this study confirmed neuroprotection action of ibuprofen through intranasal MMEI against MPTP induced inflammation in dopaminergic nerves in animal model and hence, MMEI can be useful for prevention and management of Parkinson disease (PD).

Bivalent Approach for Homodimeric Estradiol Based Ligand: Synthesis and Evaluation for Targeted Theranosis of ER(+) Breast Carcinomas.

The synthesis of estradiol based bivalent ligand [(EST)2DT] is reported and its potential for targeted imaging and therapy of ER(+) tumors has been evaluated. For the purpose, ethinylestradiol was functionalized with an azidoethylamine moiety via click chemistry. The resultant derivative was reacted in a bivalent mode with DTPA-dianhydride to form the multicoordinate chelating agent, (EST)2DT which displayed capability to bind (99m)Tc. The radiolabeled complex, (99m)Tc-(EST)2DT was obtained in >99% radiochemical purity and 20-48 GBq/µmol of specific activity. RBA assay revealed ∼15% binding with estrogen receptor. Evaluation of ligand on ER(+)-cell line (MCF-7) suggested enhanced and ER-mediated uptake. In vivo assays displayed early tracer accumulation in MCF-7 xenografts with tumor to muscle ratio ∼6 in 2 h and negligible uptakes in nontargeted organs. MTT assay performed on ER(+) and ER(-) cell lines displayed selective inhibition of ER(+) cancer cell growth with IC50 = 14.3 µM which was comparable to tamoxifen. The anticancer activity of the ligand is possibly due to the increase in ERß and suppression of ERα protein levels in gene transcription. The studies reveal the potential of (EST)2DT as diagnostic imaging agent with the additional benefits in therapy.

Luteinizing hormone-releasing hormone peptide tethered nanoparticulate system for enhanced antitumoral efficacy of paclitaxel.

AIM: Paclitaxel (PTX) is an effective anticancer agent used in the therapy of a wide variety of cancers. However, the drug is difficult to formulate due to its low solubility, and therefore, it is administered under slow infusion with castor oil/ethanol solution as surfactant that causes serious side effects. This investigation investigates leutinizing hormone releasing hormone (LHRH)-tethered nanparticulate system as modality for cancer-specific delivery of PTX and therefore minimizing the adverse effects. MATERIALS & METHODS: LHRH-tethered poly(lactic-co-glycolic acid) copolymer with poly ethylene glycol side chain was synthesized, characterized and employed to formulate PTX-loaded nanoparticulate system. RESULTS & CONCLUSION: The developed nanoparticulate appears to be proficient in carrying as well as targeted delivery of PTX with improved therapeutic efficacy and better safety.

Synthesis, Characterization, and Preclinical Evaluation of (99m)Tc-Labeled Macrobicyclic and Tricyclic Chelators as Single Photon Emission Computed Tomography Tracer.

The novel tetraaza macrobicyclic chelator 3,6,9,15-tetraazabicyclo[9.3.1]pentadeca-1(15),11,13-triene-2,10-dione (TBPD) and pentaaza macrotricyclic chelator 9-oxa-3,6,12,15,21-pentaazatricyclo[15,3,2,1]trieicos-1(21),17,19-triene-2,7,11,16-tetradione (OPTT) were synthesized, characterized, and radiolabeled with (99m)Tc to produce (99m)Tc-TBPD and (99m)Tc-OPTT. These radiolabeled complexes were prepared with high radiolabeling yield, radiochemical purity, and good in vitro stability up to 24 h. The labeling efficiency of (99m)Tc-TBPD and (99m)Tc-OPTT was found 98% and 97%. In vitro serum stability of (99m)Tc-TBPD was found to be 95.2%, while that of (99m)Tc-OPTT 94.2% up to 24 h. Blood kinetics experiments of (99m)Tc-labeled complexes showed biphasic pattern of blood clearance. About 99.57 ± 0.89% activity of (99m)Tc-TBPD and 99.42 ± 0.88% activity of (9m)Tc-OPTT were cleared off blood stream at 24 h postadministration. The biological half-life of (99m) Tc-TBPD was observed: t1/2(F) 1 h 5 min and t1/2(S) 12 h and biological half-life of (99m)Tc-OPTT was observed: t1/2(F) 1 h 10 min and t1/2(S) 9 h 50 min, respectively. The biodistribution studies revealed that maximum uptake of (99m)Tc-TBPD was found in liver, concluded that excretory pathway is hepatobiliary, while that of (99m)Tc-OPTT was renal as well as hepatobiliary. The negligible activity observed in stomach confirming the stability of radiolabeled complex in biological milieu. In vitro cytotoxicity study of TBPD and OPTT did not show any considerable antiproliferative activity against cancer cells of human cervical SW756, HeLa, and glioblastoma U-87, U373 cell lines.

Design and evaluation of mucoadhesive microemulsion for neuroprotective effect of ibuprofen following intranasal route in the MPTP mice model.

BACKGROUND: The present study is to investigate the neuroprotective effect of ibuprofen by intranasal administration of mucoadhesive microemulsion (MMEI) against inflammation-mediated by dopaminergic neurodegeneration in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) model of Parkinson's disease (PD). METHODS: Ibuprofen-loaded polycarbophil-based MMEI was developed by using response surface methodology (RSM). Ibuprofen with dose of 2.86 mg/kg/day was administered intranasally to male C57BL/6 mice for two consecutive weeks which were pre-treated with four intraperitoneal injections of MPTP (20 mg/kg of body weight) at 2 h intervals. Immunohistochemistry was performed. RESULTS: Optimal MMEI was stable and non-ciliotoxic with 66.29 ± 4.15 nm as average globule size and -20.9 ± 3.98 mV as zeta potential. PDI value and transmission electron microscopy result showed the narrow globule size distribution of MMEI. The result showed that all three independent variables had a significant effect (p < 0.05) on the responses. Rota-rod and open-field test findings revealed the significant improvement in motor performance and gross behavioral activity of the mice. The results from in vivo study and immunohistochemistry showed that nasal administration of Ibuprofen significantly reduced the MPTP-mediated dopamine depletion. Furthermore TH neurons count in the substantia nigra and the density of striatal dopaminergic nerve terminals were found to be significant higher for ibuprofen treated groups. CONCLUSION: Findings of the investigation revealed that Ibuprofen through developed MMEI was shown to protect neurons against MPTP-induced injury in the Substantia nigra pars compacta (SNpc) and striatum and hence, could be a promising approach for brain targeting of Ibuprofen through intranasal route to treat PD.

Preclinical Evaluation of DMA, a Bisbenzimidazole, as Radioprotector: Toxicity, Pharmacokinetics, and Biodistribution Studies in Balb/c Mice.

Radiotherapy, a therapeutic modality of cancer treatment, nonselectively damages normal tissues as well as tumor tissues. The search is ongoing for therapeutic agents that selectively reduce radiation-induced normal tissue injury without reducing tumoricidal effect, thereby increasing the therapeutic ratio of radiation therapy. Our laboratory established 5-(4-methylpiperazin-1-yl)-2-[2'-(3,4-dimethoxyphenyl)-5'benzimidazolyl] benzimidazole (DMA) as noncytotoxic radioprotector in mammalian cells. DMA showed an excellent radioprotection in mice at single nontoxic oral dose by a dose-reduction factor of 1.28. An oxygen radical absorbing capacity assay confirmed its free-radical quenching ability. Single bolus dose and 28-days of repeated administration of DMA in mice for toxicity studies determined an LD50 of >2000 mg/kg body weight (bw) and 225 mg/kg bw, respectively, suggesting DMA is safe. Histopathology, biochemical parameters, and relative organ weight analysis revealed insignificant changes in the DMA-treated animals. The pharmacokinetic study of DMA at oral and intravenous doses showed its C(max) = 1 hour, bioavailability of 8.84%, elimination half-life of 4 hours, and an enterohepatic recirculation. Biodistribution study in mice with Ehrlich ascites tumors showed that (99m)Tc-DMA achieved its highest concentration in 1 hour and was retained up to 4 hours in the lungs, liver, kidneys, and spleen, and in a low concentration in the tumor, a solicited property of any radioprotector to protect normal cells over cancerous cells. We observed that the single-dose treatment of tumor-bearing mice with DMA 2 hours before 8 Gy total body irradiation showed an impressive rescue of radiation-induced morbidity in terms of weight loss and mortality without a change in tumor response.

Preclinical Evaluation of a Potential GSH Ester Based PET/SPECT Imaging Probe DT(GSHMe)2 to Detect Gamma Glutamyl Transferase Over Expressing Tumors.

Gamma Glutamyl Transferase (GGT) is an important biomarker in malignant cancers. The redox processes ensuing from GGT-mediated metabolism of extracellular GSH are implicated in critical aspects of tumor cell biology. Reportedly, Glutathione monoethyl ester (GSHMe) is a substrate of GGT, which has been used for its rapid transport over glutathione. Exploring GGT to be an important target, a homobivalent peptide system, DT(GSHMe)2 was designed to target GGT-over expressing tumors for diagnostic purposes. DT(GSHMe)2 was synthesized, characterized and preclinically evaluated in vitro using toxicity, cell binding assays and time dependent experiments. Stable and defined radiochemistry with 99mTc and 68Ga was optimized for high radiochemical yield. In vivo biodistribution studies were conducted for different time points along with scintigraphic studies of radiolabeled DT(GSHMe)2 on xenografted tumor models. For further validation, in silico docking studies were performed on GGT (hGGT1, P19440). Preclinical in vitro evaluations on cell lines suggested minimal toxicity of DT(GSHMe)2 at 100 µM concentration. Kinetic analysis revealed transport of 99mTc-DT(GSHMe)2 occurs via a saturable high-affinity carrier with Michaelis constant (Km) of 2.25 µM and maximal transport rate velocity (Vmax) of 0.478 µM/min. Quantitative estimation of GGT expression from western blot experiments showed substantial expression with 41.6 ± 7.07 % IDV for tumor. Small animal micro PET (Positron Emission Tomography)/CT(Computed Tomography) coregistered images depicted significantly high uptake of DT(GSHMe)2 at the BMG-1 tumor site. ROI analysis showed high tumor to contra lateral muscle ratio of 9.33 in PET imaging studies. Avid accumulation of radiotracer was observed at tumor versus inflammation site at 2 h post i.v. injection in an Ehrlich Ascites tumor (EAT) mice model, showing evident specificity for tumor. We propose DT(GSHMe)2 to be an excellent candidate for prognostication and tumor imaging using PET/SPECT.

Preclinical evaluation of (99m)Tc labeled gefitinib as a potential scintigraphic probe for the detection of tumors expressing epidermal growth factor receptors.

In the present study, we successfully radiolabeled gefitinib with (99m)Tc by direct labeling method. The radio-ligand had radiolabeling efficiency of >95.0% and in vitro stability of >80.0% at 24h. The radiotracer cleared from blood bi-exponentially. Animal organ biodistribution data indicated hepato-renal excretion of the radiotracer. Scintigraphy carried out in tumor bearing mice (induced by EGFR expressing EAT cell lines) demonstrated that the radiotracer accumulated in the tumor site with T/NT ratio of 3.3±0.2 at 1h.

Metal based imaging probes of DO3A-Act-Met for LAT1 mediated methionine specific tumors: synthesis and preclinical evaluation.

PURPOSE: Tumor cells are known to have an elevated requirement for methionine due to increased protein synthesis and trans-methylation reactions. A methionine based macrocyclic tumor imaging system, DO3A-Act-Met, has been designed to provide a novel platform for tumor imaging via modalities, PET/MRI using metal ions, (68)Ga and (157)Gd. METHODS: Synthesis of DO3A-Act-Met was confirmed through NMR and mass spectrometric techniques. Cytotoxicity of complexes was evaluated using MTT assay whereas receptor binding and trans-stimulation studies were performed on EAT and U-87 MG cell lines. Tumor targeting was assessed through imaging and biodistribution experiments on U-87 MG xenograft model. RESULTS: DO3A-Act-Met was synthesized and radiolabeled with (68)Ga in high radiochemical purity (85-92%). The receptor binding assay on EAT cells predicted high binding affinity with Kd of 0.78 nM. Efflux of (35)S-L-methionine trans-stimulated by extracellular DO3A-Act-Met on U-87MG cells suggested an L-system transport. MR studies revealed a longitudinal relaxivity of 4.35 mM(-1) s(-1) for Gd-DO3A-Act-Met and a 25% signal enhancement at tumor site. The biodistribution studies in U-87MG xenografts validated tumor specificity. CONCLUSION: DO3A-Act-Met, a methionine conjugated probe is a promising agent for targeted molecular imaging, exhibiting high specificity towards tumor owing to its essential role in proliferation of cancer cells mediated through LAT1.

Mucoadhesive microemulsion of ibuprofen: design and evaluation for brain targeting efficiency through intranasal route

This study aimed at designing mucoadhesive microemulsion gel to enhance the brain uptake of Ibuprofen through intranasal route. Ibuprofen loaded mucoadhesive microemulsion (MMEI) was developed by incorporating polycarbophil as mucoadhesive polymer into Capmul MCM based optimal microemulsion (MEI) and was subjected to characterization, stability, mucoadhesion and naso-ciliotoxicity study. Brain uptake of ibuprofen via nasal route was studied by performing biodistribution study in Swiss albino rats. MEI was found to be transparent, stable and non ciliotoxic with 66.29 ± 4.15 nm, -20.9 ± 3.98 mV and 98.66 ± 1.01% as average globule size, zeta potential and drug content respectively. Transmission Electron Microscopy (TEM) study revealed the narrow globule size distribution of MEI. Following single intranasal administration of MMEI and MEI at a dose of 2.86 mg/kg, uptake of ibuprofen in the olfactory bulb was around 3.0 and 1.7 folds compared with intravenous injection of ibuprofen solution (IDS). The ratios of AUC in brain tissues to that in plasma obtained after nasal administration of MMEI were significantly higher than those after intravenous administration of IDS. Findings of the present investigation revealed that the developed mucoadhesive microemulsion gel could be a promising approach for brain targeting of ibuprofen through intranasal route.

O objetivo deste trabalho foi planejar microemulsão/mucoaesiva em gel a fim de melhorar a captação cerebral de ibuprofeno por via intranasal. A microemulsão para mucoadesão com ibuprofeno (MMEI) foi desenvolvida pela incorporação de policarbofil como polímero mucoadesivo em microemulsão otimizada (MEI) com base em Capmul (MCM) e foi submetida à caracterização, estabilidade, mucoadesão e naso-ciliotoxicidade. A captação cerebral de ibuprofeno pela via nasal foi estudada por meio de estudo de biodistribuição em ratos albinos suíços. MEI se mostrou transparente, estável e não ciliotóxica, com 66,29 ± 4,15 nm, -20,9 ± 3,98 mV e 98,66 ± 1,01%, respectivamente, de tamanho médio dos glóbulos, potencial zeta e conteúdo do fármaco. O estudo revelou o estreita distribuição do tamanho dos glóbulos de MEI. Após administração intranasal única de MMEI e MEI, em dose de 2,86 mg/kg, a captação de ibuprofeno no bulbo olfativo foi em torno de 3,0 e 1,7 vezes maior, comparativamente, à injeção endovenosa de ibuprofeno (IDS). As taxas de ASC em tecido cerebral em relação ao plasma, obtidas após administração da MMEI nasal, foram, significativamente, mais elevadas do que aquelas observadas após a administração intravenosa de IDS. Os resultados do presente estudo mostraram que a microemulsão/mucoadesiva em gel poderia ser uma abordagem promissora para o direcionamento cerebral de ibuprofeno por via intranasal.

LAT-1 based primary breast cancer detection by [99m]Tc-labeled DTPA-bis-methionine scintimammography: first results using indigenously developed single vial kit preparation.

OBJECTIVE: To evaluate the diagnostic utility of a single vial ready to label with [99m]Tc kit preparation of DTPA-bis-methionine (DTPA-bis-MET) for the detection of primary breast cancer. METHODS: The conjugate (DTPA-bis-MET) was synthesized by covalently conjugating two molecules of methionine to DTPA and formulated as a single vial ready to label with [99m]Tc lyophilized kit preparations. Thirty female patients (mean age=47.5±11.8 years; range=21-69 years) with radiological/clinical evidence of having primary breast carcinoma were subjected to [99m]Tc-methionine scintigraphy. The whole body (anterior and posterior) imaging was performed on all the patients at 5 minutes, 10 minutes, 1 hour, 2 hours, and 4 hours following an intravenous administration of 555-740 MBq radioactivity of [99m]Tc-methionine. In addition, scintimammography (static images; 256×256 matrix) at 1, 2, and 4 hours was also performed on all the patients. RESULTS: The resultant radiolabel, that is, [99m]Tc-DTPA-bis-MET, yielded high radiolabeling efficiency (>97.0%), radiochemical purity (166-296 MBq/µmol), and shelf life (>3 months). The radiotracer primarily gets excreted through the kidneys and localizes in the breast cancer lesions with high target-to-nontarget ratios. The mean±SD ratios on the scan-positive lesions acquired at 1, 2, and 4 hours postinjection were 3.6±0.48, 3.10±0.24, and 2.5±0.4, respectively. [99m]Tc-methionine scintimammography demonstrated an excellent sensitivity and positive predictive value of 96.0% each for the detection of primary breast cancer. CONCLUSION: Ready to label single vial kit formulations of DTPA-bis-MET can be easily synthesized as in-house production and conveniently used for the scintigraphic detection of breast cancer and other methionine-dependent tumors expressing the L-type amino acid transporter-1 receptor. The imaging technique thus could be a potential substitute for the conventional single-photon emission computed tomography (SPECT)-based tumor imaging agents, especially for tracers with nonspecific mitochondrial uptake. However, the diagnostic efficacy of [99m]Tc-methionine needs to be evaluated in a large cohort of patients through further multicentric trials.

Solid-nanoemulsion preconcentrate for oral delivery of paclitaxel: formulation design, biodistribution, and γ scintigraphy imaging.

Aim of present study was to develop a solid nanoemulsion preconcentrate of paclitaxel (PAC) using oil [propylene glycol monocaprylate/glycerol monooleate, 4:1 w/w], surfactant [polyoxyethylene 20 sorbitan monooleate/polyoxyl 15 hydroxystearate, 1:1 w/w], and cosurfactant [diethylene glycol monoethyl ether/polyethylene glycol 300, 1:1 w/w] to form stable nanocarrier. The prepared formulation was characterized for droplet size, polydispersity index, and zeta potential. Transmission electron microscopy (TEM), differential scanning calorimetry (DSC), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) were used to assess surface morphology and drug encapsulation and its integrity. Cumulative drug release of prepared formulation through dialysis bag and permeability coefficient through everted gut sac were found to be remarkably higher than the pure drug suspension and commercial intravenous product (Intaxel), respectively. Solid nanoemulsion preconcentrate of PAC exhibited strong inhibitory effect on proliferation of MCF-7 cells in MTT assay. In vivo systemic exposure of prepared formulation through oral administration was comparable to that of Intaxel in γ scintigraphy imaging. Our findings suggest that the prepared solid nanoemulsion preconcentrate can be used as an effective oral solid dosage form to improve dissolution and bioavailability of PAC.

(68)Ga based probe for Alzheimer's disease: synthesis and preclinical evaluation of homodimeric chalcone in ß-amyloid imaging.

In an attempt to explore use of PET radioisotope, (68)Ga, in the diagnosis of Alzheimer's disease, a metal-based homodimeric ligand exhibiting high affinity towards Aß aggregates was designed by conjugating two chalcone units with the chelating system, diethylenetriaminepentaacetic acid. Bischalcone derivative, 5,8-bis(carboxymethyl)-13-(4-((E)-3-(4-(dimethylamino)phenyl)acryloyl)phenoxy)-2-(2-(2-(4-((E)-3-(4-(dimethylamino)phenyl)acryloyl)phenoxy)ethylamino)-2-oxoethyl)-10-oxo-2,5,8,11-tetraazatridecane-1-carboxylic acid, DT(Ch)2 was synthesized in 95% yield with high purity. It was radiolabelled with (68)Ga under mild conditions with 85.4% efficiency and 9.5-10 MBq nmol(-1) specific activity. An in vitro binding assay on Aß42 aggregates displayed high binding affinity of (68)Ga-DT(Ch)2 and inhibition constant of 4.18 ± 0.62 nM. The fluorescent properties of the ligand with peaks of absorption/emission at 410/540 nm exhibited a blue shift with 5.5-fold increase in emission intensity on binding with Aß aggregates. Blood kinetics of the complex performed on normal rabbit exhibited fast clearance (t1/2(F) = 24 ± 0.08 min; t1/2(S) = 2 h 40 ± 0.04 min). Ex vivo biodistribution analysis demonstrated blood-brain barrier penetration with brain uptake of 1.24 ± 0.31% ID g(-1) at 2 min p.i. and rapid washout with negligible activity (0.36% ID g(-1)) left at 30 min p.i. These preliminary studies reveal that the bivalent approach of synthesis had minimal effect on binding affinity, signifying that the developed (68)Ga-complex, (68)Ga-DT(Ch)2, may offer a new perspective in generator produced PET imaging probes for Alzheimer's disease.

Topical delivery of fluorescence (6-Cf) labeled and radiolabeled (99m-Tc) cisplatin and imiquimod by a dual drug delivery system.

The present investigation deals with the development of topical (top.) formulation for co-delivery of cisplatin and imiquimod to enhance the antitumor efficacy of the drug for skin-cited malignancies even in immune compromised patient. Cisplatin (CDDP) and imiquimod-loaded protransfersome gel (CDDP-Imi-Pts gel) formulation was characterized for entrapment efficiency, pH, and viscosity. Further, fluorescence-labeled (6-carboxyfluorescin) and radiolabeled ((99m) technetium) drug-loaded formulations were compared with respect to biodistribution and pharmacokinetic studies. Gamma scintigraphy of mice following radiolabeled formulation administrations was performed to accomplish the localization of drugs in various organs. The percentage entrapment efficiency of cisplatin and imiquimod in the protransfersome gel formulations were found to be 36.22 ± 6.41 and 63.11 ± 3.73. The skin/blood localization ratio of 1.096, 120.13, 0.174, and 349.88 was found for intraperitoneal radiolabeled drug solution ((99m-)Tc-CDDP-Imi-Sol), top. radiolabeled drug-loaded protransfersome gel formulation ((99m-)Tc-CDDP-Imi-Pts gel), intraperitoneal 6-carboxyfluorescin labeled drug solution (6-Cf-CDDP-Imi-Sol), top. 6-carboxyfluorescin labeled drug-loaded protransfersome gel formulation (6-Cf-CDDP-Imi-Pts gel), respectively after 0.5h of administration. CDDP-Imi-Pts gel has a potential for site specific delivery and reduces the systemic toxicity of anti cancer drugs. These findings suggest that the cisplatin-imiquimod co-delivery offers an attractive, novel approach for treatment of skin-cited malignancies.

Bis(methylpyridine)-EDTA derivative as a potential ligand for PET imaging: synthesis, complexation, and biological evaluation.

A novel transitional metal ligand derivatized from EDTA-conjugated 2-amino-4-methyl pyridine, an acyclic vehicle (EDTA-Mepy2 ) was designed, synthesized, and characterized for PET imaging with 68Ga. The drug likeliness and appropriate lipophilicity were first analyzed by molecular docking studies which shows interactive property of ligand with serum albumin protein (HSA: PDB 1E78), at Lys199, Arg257, and His242 residues, which make it more appropriate in transportation as a specific ligand for PET imaging. As a confirmation, binding constant of the ligand with human serum albumin was calculated at λex = 350 nm which was found to be 4.9 × 10³ m⁻¹. The pharmacokinetics of (68) Ga-EDTA-Mepy2 was analyzed by blood kinetics (t(1/2) slow: 3 h 56 min and t(1/2) fast: 32 min) and biodistribution (maximum % ID/g was found in kidney at 1 h). Further the capability of this ligand was analyzed as optical marker also, by recording λex = 380 nm, RFU = 8000; 710 nm, RFU = 1000 units at fixed λem = 280 nm. Additionally, in physiological conditions where its stability was calculated, suggests 15-20 times selectivity over the endogenously present metal ions (KG aL /KZ nL = 14.3, KG aL /KC uL = 18.1).

In situ gelling dorzolamide loaded chitosan nanoparticles for the treatment of glaucoma.

The most important risk associated with glaucoma is the onset and progression of intraocular pressure. The objective of this study was to formulate in situ gel of chitosan nanoparticles to enhance the bioavailability and efficacy of dorzolamide in the glaucoma treatment. Optimized nanoparticles were spherical in shape (particle size: 164 nm) with a loading efficiency of 98.1%. The ex vivo release of the optimized in situ gel nanoparticle formulation showed a sustained drug release as compared to marketed formulation. The gamma scintigraphic study of prepared in situ nanoparticle gel showed good corneal retention compared to marketed formulation. HET-CAM assay of the prepared formulation scored 0.33 in 5 min which indicates the non-irritant property of the formulation. Thus in situ gel of dorzolamide hydrochloride loaded nanoparticles offers a more intensive treatment of glaucoma and a better patient compliance as it requires fewer applications per day compared to conventional eye drops.

Potential carriers of chemotherapeutic drugs: matrix based nanoparticulate polymeric systems.

In this work matrix based nanoparticulate polymer systems have been designed using the diacrylate derivative of the well-known biocompatible polymer, poly(ethylene glycol) (PEG). This has been crosslinked using bifunctional (ethyleneglycol dimethacrylate) and tetrafunctional (pentaerythritol tetraacrylate) crosslinkers in varied concentrations (10-90%) to result in a polymeric network. The crosslinked polymers thus obtained were characterized by spectroscopic techniques (NMR and FTIR) and then prepared nanoparticles by the nanoprecipitation technique. Particle size analysis showed sizes of ~150 nm (PDI < 1) (with tetrafunctional crosslinker) and ~300 nm (with bifunctional crosslinker). Both the systems however showed unimodal narrow particle size distributions with negative zeta potential values of -15.6 and -7.3 respectively. Cytotoxicity of these formulations was evaluated by MTT assay showing non-cytotoxic nature of these carrier systems. In vitro drug loading and release studies were carried out using a model chemotherapeutic drug, methotrexate(MTX). These MTX loaded nanoformulations have also been evaluated biologically with the help of in vivo studies using radiolabeling techniques (with 99mTc radionuclide). The blood kinetics profile of the formulations was studied on New Zealand Albino rabbits while the biodistribution studies were performed on balb/c mice (with EAT tumours), which revealed a hepatobiliary mode of elimination. These preliminary studies clearly demonstrated the ability of these multifunctional crosslinkers to result in tight nanosized networks with biocompatible polymers such as PEG and their potential to carry chemotherapeutic drugs.

Intranasal delivery of streptomycin sulfate (STRS) loaded solid lipid nanoparticles to brain and blood.

Factors like unreliable and poor oral absorption, including an active Pgp-efflux point towards a compromised oral bioavailability (BA) of streptomycin sulfate (STRS). Latter instigates its parenteral use (i.m.) only. Furthermore, its chronic use leads to serious side effects like nephrotoxicity and ototoxicity. In the present study, we propose to develop streptomycin sulfate (STRS) loaded solid lipid nanoparticles (STRS-SLNs) for non-invasive intranasal (IN) delivery. STRS-SLNs were prepared using patented nanocolloidal aqueous dispersion technique (Indian Patent application 3093/DEL/2012). Small particle size (140.1±7.0 nm) and significant entrapment efficiency (54.83±2.1%) was achieved. Biodistribution studies using (99m)Tc showed a 3.15 and 11.0 times higher concentrations in the brain and blood of mice, respectively, on IN administration of STRS-SLNs in comparison to free (F)-STRS. Lower concentrations (3.3 times) in kidneys implicate lower nephrotoxicity. Similarly a 12 and 4 times lower levels of drug in liver and spleen, respectively upon administration of STRS-SLNs as compared to F-STRS also indicate its lesser accumulation in these reticuloendothelial system organs. Lipophillic enclosure imparted to STRS, coupled with small particle size, and its purported ability to inhibit Pgp-efflux due to the presence of tween 80, is considered to be responsible for a better BA shown by STRS upon incorporation into SLNs. This is predicted to result in an effective treatment of all types of tuberculosis including cerebral tuberculosis as indicated by high relative distribution to brain in comparison to free-STRS.