Targeting anticancer drugs to the brain: II. Physiological pharmacokinetic model of oxantrazole following intraarterial administration to rat glioma-2 (RG-2) bearing rats

Green synthesis, characterization, enhanced functionality and biological evaluation of silver nanoparticles based on Coriander sativum

The present study focused on the green synthesis of silver nanoparticles from Coriander sativum (CS) containing structural polymers, phenolic compounds and glycosidic bioactive macromolecules. Plant phenolic compounds can act as antioxidants, lignin, and attractants like flavonoids and carotenoids. Henceforth, silver nanoparticles (AgNPs) were prepared extracellularly by the combinatorial action of stabilizing and reduction of the CS leaf extract. The biologically synthesized CS-AgNPs were studied by UV-spectroscopy, zeta potential determination, scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) analysis to characterize and confirm the formation of crystalline nanoparticles. The synthesized nanoparticles demonstrated strong antimicrobial activity against all microbial strains examined with varying degrees. The scavenging action on free radicals by CS-AgNPs showed strong antioxidant efficiency with superoxide and hydroxyl radicals at different concentrations as compared with standard ascorbic acid. The presence of in vitro anticancer effect was confirmed at different concentrations on the MCF-7 cell line as revealed with decrease in cell viability which was proportionately related to the concentration of CS-AgNPs illustrating the toxigenic nature of synthesized nanoparticles on cancerous cells.

Multifarious Pharmacological Applications of Green Routed Eco-Friendly Iron Nanoparticles Synthesized by Streptomyces Sp. (SRT12)

A simple, eco-friendly, green routine co-precipitation method was experimented to synthesize iron nanoparticles (Fe-NPs) using the cell-free supernatant of actinobacteria. The biosynthesized nanoparticles were characterized by UV-Vis spectroscopy, X-ray diffractometer (XRD), energy-dispersive X-ray (EDX), scanning electron microscopy (SEM), atomic force microscopy (AFM), zeta potential analyser and Fourier transform infrared (FTIR) spectroscopy. The synthesized nanoparticles were crystalline, quasi-spherical in shape and their average size ranged from 65.0 to 86.7 nm. In our radical scavenging assays, the nanoparticles have revealed a strong antioxidant activity with respective standard ascorbic acid. The nanoparticles also exhibited a wide bactericidal action on pathogens namely Bacillus subtilis, Staphylococcus aureus, Klebsiella pneumoniae, Shigella flexneri and Escherichia coli. At 75 μg/ml concentration, the nanoparticles showed the highest inhibition against S. aureus (16.2 ± 0.45 mm), the lowest zone of inhibition was seen against K. pneumoniae (12.3 ± 0.50 mm) and moderate inhibition on other strains. Further, its cytotoxicity was seen as effective against DU145 and PC3 cells. The morphological changes caused in the prostate cell lines due to antiproliferative effect were observed through DAPI and AO/EB staining. This synthesis method specifies a new route for biosynthesis of Fe-NPs and the accomplished results illustrates that it can be used for a wide range of biomedical applications.

Pharmaceutical Applications of Iron-Oxide Magnetic Nanoparticles

Advances of nanotechnology led to the development of nanoparticulate systems with many advantages due to their unique physicochemical properties. The use of iron-oxide magnetic nanoparticles (IOMNPs) in pharmaceutical areas increased in the last few decades. This article reviews the conceptual information about iron oxides, magnetic nanoparticles, methods of IOMNP synthesis, properties useful for pharmaceutical applications, advantages and disadvantages, strategies for nanoparticle assemblies, and uses in the production of drug delivery, hyperthermia, theranostics, photodynamic therapy, and as an antimicrobial. The encapsulation, coating, or dispersion of IOMNPs with biocompatible material(s) can avoid the aggregation, biodegradation, and alterations from the original state and also enable entrapping the bioactive agent on the particle via adsorption or covalent attachment. IOMNPs show great potential for target drug delivery, improving the therapy as a consequence of a higher drug effect using lower concentrations, thus reducing side effects and toxicity. Different methodologies allow IOMNP synthesis, resulting in different structures, sizes, dispersions, and surface modifications. These advantages support their utilization in pharmaceutical applications, and getting suitable drug release control on the target tissues could be beneficial in several clinical situations, such as infections, inflammations, and cancer. However, more toxicological clinical investigations about IOMNPs are necessary.

Synthesis and surface engineering of iron oxide nanoparticles for biomedical applications

Superparamagnetic iron oxide nanoparticles (SPION) with appropriate surface chemistry have been widely used experimentally for numerous in vivo applications such as magnetic resonance imaging contrast enhancement, tissue repair, immunoassay, detoxification of biological fluids, hyperthermia, drug delivery and in cell separation, etc. All these biomedical and bioengineering applications require that these nanoparticles have high magnetization values and size smaller than 100 nm with overall narrow particle size distribution, so that the particles have uniform physical and chemical properties. In addition, these applications need special surface coating of the magnetic particles, which has to be not only non-toxic and biocompatible but also allow a targetable delivery with particle localization in a specific area. To this end, most work in this field has been done in improving the biocompatibility of the materials, but only a few scientific investigations and developments have been carried out in improving the quality of magnetic particles, their size distribution, their shape and surface in addition to characterizing them to get a protocol for the quality control of these particles. Nature of surface coatings and their subsequent geometric arrangement on the nanoparticles determine not only the overall size of the colloid but also play a significant role in biokinetics and biodistribution of nanoparticles in the body. The types of specific coating, or derivatization, for these nanoparticles depend on the end application and should be chosen by keeping a particular application in mind, whether it be aimed at inflammation response or anti-cancer agents. Magnetic nanoparticles can bind to drugs, proteins, enzymes, antibodies, or nucleotides and can be directed to an organ, tissue, or tumour using an external magnetic field or can be heated in alternating magnetic fields for use in hyperthermia. This review discusses the synthetic chemistry, fluid stabilization and surface modification of superparamagnetic iron oxide nanoparticles, as well as their use for above biomedical applications.

Tissue distribution of terbinafine in rats

Terbinafine is an allylamine antifungal agent that is highly lipophilic and keratophilic. The aim of this study was to investigate terbinafine distribution in peripheral and visceral tissues after intravenous administration to rats. Terbinafine, 6 mg/kg, was administered to 33 male Sprague-Dawley rats via a jugular vein cannula over 30 s. Groups of 3 rats were sacrificed at each of 11 time points (up to 24 h), and plasma and tissues were dissected, sampled, and analyzed by high-performance liquid chromatography. Terbinafine plasma concentrations declined in a triexponential fashion, with an estimated elimination half-life of 10 h. The estimated clearance of terbinafine in rats was 2 L/h/kg and the volume of distribution at steady state was 6 L/kg. The tissue-to-plasma partition coefficient (K(p)) of terbinafine for different tissues was calculated using the ratio of the area under the curve of concentration-time for tissues (AUC(tissue)) to that for plasma (AUC(plasma)), by parametric and semiparametric approaches. There was good agreement between K(p) estimates determined by different approaches. The preferential distribution of terbinafine to adipose and skin (K(p) = 49 and 45, respectively) was consistent with the lipophilicity of the drug. Uptake of terbinafine into brain (K(p) = 1.3) and muscle (K(p) = 1.0) was significantly lower. In conclusion, terbinafine displays extensive uptake to peripheral tissues, which contributes to the long elimination half-life of this drug.

Rat brain tumor models in experimental neuro-oncology: the 9L, C6, T9, F98, RG2 (D74), RT-2 and CNS-1 gliomas

Rat brain tumor models have been widely used in experimental neuro-oncology for almost three decades. The present review, which will be selective rather than comprehensive, will focus entirely on seven rat brain tumor models and their utility in evaluating the efficacy of various therapeutic modalities. Although no currently available animal brain tumor model exactly simulates human high grade brain tumors, the rat models that are currently available have provided a wealth of information on in vitro and in vivo biochemical and biological properties of brain tumors and their in vivo responses to various therapeutic modalities. Ideally, valid brain tumor models should be derived from glial cells, grow in vitro and in vivo with predictable and reproducible growth patterns that simulate human gliomas, be weakly or non-immunogenic, and their response to therapy, or lack thereof, should resemble human brain tumors. The following tumors will be discussed. The 9L gliosarcoma, which was chemically induced in an inbred Fischer rat, has been one of the most widely used of all rat brain tumor models and has provided much useful information relating to brain tumor biology and therapy. The T9 glioma, although generally unrecognized, was and probably still is the same as the 9L. Both of these tumors can be immunogenic under the appropriate circumstances, and this must be taken into consideration when using either of them for studies of therapeutic efficacy, especially if survival is used as an endpoint. The C6 glioma, which was chemically induced in an outbred Wistar rat, has been extensively used for a variety of studies, but is not syngeneic to any inbred strain. Its potential to evoke an alloimmune response is a serious limitation, if it is being used in survival studies. The F98 and RG2 (D74) gliomas were both chemically induced tumors that appear to be either weakly or non-immunogenic. These tumors have been refractory to a variety of therapeutic modalities and their invasive pattern of growth and uniform lethality following an innoculum of as few as 10 tumor cells make them particularly attractive models to test new therapeutic modalities. The Avian Sarcoma Virus induced tumors and a continuous cell line derived from one of them, designated RT-2, have been useful for studies in which de novo tumor induction is an important requirement. These tumors, however, are immunogenic and this may limit their usefulness for survival studies. Finally, a new chemically induced tumor recently has been described, the CNS-1, and it appears to have a number of properties that should make it useful in experimental neuro-oncology. It is essential to recognize, however, the limitations of each of the models that have been described, and depending upon the nature of the study to be conducted, it is important that the appropriate model be selected.

Physiologically based pharmacokinetic study on a cyclosporin derivative, SDZ IMM 125

The immunosuppressant, SDZ IMM 125 (IMM), is a derivative of cyclosporin A (CyA). The disposition kinetics of IMM in plasma, blood cells, and various tissues of the rat was characterized by a physiologically based pharmacokinetic (PBPK) model; the model was then applied to predict the disposition kinetics in dog and human. Accumulation of IMM in blood cell is high (equilibrium blood cell/plasma ratio = 8), although the kinetics of drug transference between plasma and blood cell is moderately slow, taking approximately 10 min to reach equilibrium, implying a membrane-limited distribution into blood cells. A local PBPK model, assuming blood-flow limited distribution and tissue/blood partition coefficient (KP) data, failed to adequately describe the observed kinetics of distribution, which were slower than predicted. A membrane transport limitation is therefore needed to model dynamic tissue distribution data. Moreover, a slowly interacting intracellular pool was also necessary to adequately describe the kinetics of distribution in some organs. Three elimination pathways (metabolism, biliary secretion, and glomerular filtration) of IMM were assessed at steady state in vivo and characterized independently by the corresponding clearance terms. A whole-body PBPK model was developed according to these findings, which described closely the IMM concentration-time profiles in arterial blood as well as 14 organs/tissues of the rat after intravenous administration. The model was then scaled up to larger mammals by modifying physiological parameters, tissue distribution and elimination clearances; in vivo enzymatic activity was considered in the scale-up of metabolic clearance. The simulations agreed well with the experimental measurements in dog and human, despite the large interspecies difference in the metabolic clearance, which does not follow the usual allometric relationship. In addition, the nonlinear increase in maximum blood concentration and AUC with increasing dose, observed in healthy volunteers after intravenous administration, was accommodated quantitatively by incorporating the known saturation of specific binding of IMM to blood cells. Overall, the PBPK model provides a promising tool to quantitatively link preclinical and clinical data.

Comparative physiological pharmacokinetics of fentanyl and alfentanil in rats and humans based on parametric single-tissue models

The objectives of this investigation were to characterize the disposition of fentanyl and alfentanil in 14 tissues in the rat, and to create physiological pharmacokinetic models for these opioids that would be scalable to man. We first created a parametric submodel for the disposition of either drug in each tissue and then assembled these submodels into whole-body models. The disposition of fentanyl and alfentanil in the heart and brain and of fentanyl in the lungs could be described by perfusion-limited 1-compartment models. The disposition of both opioids in all other examined tissues was characterized by 2- or 3-compartment models. From these models, the extraction ratios of the opioids in the various tissues could be calculated, confirming the generally lower extraction of alfentanil as compared to fentanyl. Assembly of the single-tissue models resulted in a wholebody model for fentanyl that accurately described its disposition in the rat. A similar assembly of the tissue models for alfentanil revealed non-first-order elimination kinetics that were not apparent in the blood concentration data. Michaelis-Menten parameters for the hepatic metabolism of alfentanil were determined by iterative optimization of the entire model. The parametric models were finally scaled to describe the disposition of fentanyl and alfentanil in humans.