Classification and application of colloidal drug delivery systems: Passive or active tumor targeting

[No abstract available

Places of microemulsion and emulsion in cancer therapy: In vitro and in vivo evaluation

Cancer is one of the most challenging health problems of the developing world. Cancer is actually a heterogenic group of disease which is mainly characterized by altered cell growth and apoptotic systems within the cell. All carcinogens or mutagens cause some damage to the DNA of the cell. This alteration may be in a wide pattern ranging from a single base pair mutation to chromosomal aberrations. The DNA mutations that are not repaired before the next cell division cycle pass on to the daughter cells and thus result in the accumulation of DNA mutations in the nucleus. All scientific studies on carcinogenesis show that cancer is a genetic disease caused by means of molecular change [1,2]. © 2009 by Taylor & Francis Group, LLC

Different geometric shaped hydrogel theophylline tablets: Statistical approach for estimating drug release

PubMed ID: 12484543The objective of this study was to develop a mathematical equation for the calculation of drug release from different shaped matrix tablets. By this way, release rate related to the geometric shape could be predicted with the help of the developed mathematical equation. So, drug release could be estimated before the dissolution. Hydroxypropylmethylcellulose (HPMC) E50 as polymer and theophylline as active substance were used in the matrix tablets prepared for this purpose. Matrix tablets in three different geometrical shapes, namely in triangular, cylindrical and half-spherical forms were prepared by using two different drug-polymer ratio (1:0.5, 1:1) and diluent's in three different percentages (0, 20, 40%). Using rotating paddle and basket methods reported in USP XXIII carried out the release rate studies of these tablets. The Higuchi square-root time model best described the dissolution data. Differential scanning calorimetry (DSC) analysis was performed to identify any solid-state inactivation of the drug. The practical benefit of this work is to improve mathematical equation that can be used to predict accurately the required composition and in order to achieve the desired release profiles of different geometric shaped tablets. By using this equation new pharmaceutical products can be easily improved. © 2002 Éditions scientifiques et médicales Elsevier SAS. All rights reserved

Permeation studies and histological examination of sheep nasal mucosa following administration of different nasal formulations with or without absorption enhancers

PubMed ID: 18446567This study was designed to investigate the possible histological effects of different intranasal (IN) formulations of indomethacin (IND) on nasal mucosa in sheep. For this purpose, oil-in-water (O/W) emulsion (E) and solution (S) formulations including 3 mg/mL of IND were prepared. Penetration enhancers such as polyvinylpyrolidone (PVP), citric acid (CA) and sodium taurocholate (NaT) were added to emulsion (1%) at the final step into the formulations. First, the effect of penetration enhancers on permeation of IND was evaluated by in vitro permeation studies in which sheep nasal mucosa was used. According to the permeation studies PVP showed the highest enhancing effect on the permeation rate of IND from sheep nasal mucosa. Furthermore, the IND permeation from E containing PVP (1.624 ± 0.045 mg) was significantly higher than that obtained from E (0.234 ± 0.012 mg) (p < 0.05). For the histological studies, white Karaman sheep of approximately 20 ± 5 kg, aged 4 to 8 months were used. They were randomly divided into eight groups, each including three sheep. Five experimental groups received different formulations of IND emulsion without/ with penetration enhancers (E-PVP, E-CA, E-NaT, E) and IND solution (S), respectively. Parallel controls were composed of either untreated groups and were given blank emulsion or isotonic sodium chloride solution (0.31 mg/kg). 2 mL of each experimental formulation was applied to both nostrils of sheep, and 1/3 central and lower regions of the nose were dissected and prepared for light microscopy. Specimens stained with hematoxylin and eosin and Gomori's trichrome were examined by light microscopy. No signs of inflammation or erosion were noticed in the nasal mucosa of the control groups. Widened epithelial intercellular spaces were noticed in E-CA, E-NaT, and E-PVP groups as well with the E-PVP group showing the largest intraepithelial separations. E-CA and E-NaT groups showed significant decrease in the amount of goblet cells, while hypoplasia was considerably moderate in the E-PVP group. Finally, intranasal administration of IND emulsion with PVP may be considered as an alternative to intravenous and per oral administrations of IND to overcome their adverse effects. Copyright © Informa Healthcare USA, Inc

Modeling of theophylline release from different geometrical erodible tablets

PubMed ID: 10704902The aim of this study is to reveal statistically how various geometrical shapes such as triangle, cylinder, half-sphere affect the release rate of the active substance called theophylline in erodible hydrogel matrix tablets. We have tried to indicate these changes in the release rate of theophylline by supporting our aim with the mathematical equations developed by Hopfenberg and Katzhendler et al. The model developed by Hopfenberg assumes that drug release occurs from the primary surface area of the device but Katzhendler et al. (I. Katzhendler, A. Hoffman, A. Goldberger, M. Friedman, Modelling of drug release from erodible tablets, J. Pharm. Sci. 86 (1997) 110-115), described a situation where the erosion rates of the tablet are different in the radial and axial directions. Hydrogel matrix tablets were prepared with hydroxypropylmethylcellulose (HPMC E50) possessing different geometrical shapes as triangular, cylindrical and half-spherical using experimental design. When the dissolution results have been evaluated, it has been observed theophylline release from different geometrical erodible tablets fitted with that of the Katzhendler et al., equation. This equation which was suggested for cylindrical tablets was also used to interpret half-spherical and triangular tablets. According to the above stated equation, n has been determined as 4 for triangular tablets and 1.5 for half-spherical tablets and we have also suggested that, these n values could be used in the kinetic programs. (C) 2000 Elsevier Science B.V

Improving of the accuracy of in vitro-in vivo linear correlation using kinetic models for ultra sustained release theophylline tablets

PubMed ID: 14743972The objective of the current study was to establish and evaluate a new technique to increase the accuracy of the in vitro / in vivo linear correlation of single and multiple dose ultra-sustained release theophylline (USRT) preparation (Xantium®) in hospitalized patients. In vitro dissolution data for theophylline were collected for 24 h using a USP I (basket) and USP II (paddle) methods. In vivo plasma concentration data were obtained from 8 patients after administration of either single or multiple doses of theophylline. Both in vitro and in vivo results were evaluated by zero-order, first-order, RRSBW, Hixson-Crowell, Higuchi, Hopfenberg, Langenbucher, modified Langenbucher and (Bt)a kinetic models. The individual linear correlations between each in vitro and in vivo percent results and their kinetic distributions were established and regression equations were obtained. The determination coefficient results of the linear kinetic correlations were found to be 0.994 and 0.997 for single and multiple doses by basket method and 0.992 and 0.998 for single and multiple doses by paddle method, respectively. Furthermore, the results of the linear correlations were found as 0.953 and 0.950 for single and multiple doses by basket method and 0.963 and 0.962 for single and multiple doses by paddle method respectively. Therefore, this study suggested that the accuracy of the linear correlation could be improved significantly by using linear kinetic correlation

Nanoscaled dispersed systems used in drug-delivery applications

2-s2.0-85078197107Controlled drug-delivery nanotechnology is one of the most studied science fields bringing together chemists, biologists, physicists, pharmacists, and physicians to develop interdisciplinary knowledge. The main outcome followed is the same for all, particularly human health and patient compliance. The drug discovery technology is developing continuously so that many challenges arise day by day, delivery of poorly soluble drugs being one of them. Nanoscaled dispersions represent a smart strategy to formulate poorly soluble drugs and thus to improve poor absorption profile. The huge amount of scientific reports that have already been published concerning the nanoscaled dispersions for pharmaceutical and medical purposes has justified the great attention given to this topic. This chapter reviews the studies developed in the field of nanoscale dispersion systems, in particular micro-/nanoemulsions and polymeric nanodispersions used for drug-delivery systems with a focus on the last 5 years. © 2019 Elsevier Inc. All rights reserved