Irinotecan binds to the internal cavity of beta-lactoglobulin: A multi-spectroscopic and computational investigation.

The binding of irinotecan, a potent anti cancer drug, to bovine beta-lactoglobulin (ß-LG) was investigated by various spectroscopic techniques including fluorimetry, circular dichroism (CD), UV-vis, and Fourier transform infrared (FT-IR), in 10mM phosphate buffer, pH 7.75, in combination with a molecular docking study. Analysis of the fluorescence quenching data showed that combined static and dynamic quenching occurs, with the predominant contribution of the static mode. Molecular docking results were in full agreement with the results obtained from thermodynamic analysis of the fluorescence data indicating the existence of one binding site for irinotecan in ß-LG structure and revealed the hydrophobic nature of the interaction between irinotecan and the protein. The binding distance between ß-LG and irinotecan, r, was estimated to be 5.74nm based on the Förster's theory of non-radiative energy transfer. The obtained results of near-UV CD and FT-IR experiments suggested the occurrence of partial compactness of the protein structure upon irinotecan binding. Based on the experimental data and the possible binding mode revealed by molecular docking study, we concluded that irinotecan binds to the hydrophobic calyx of ß-LG with induction of some alterations in the secondary and tertiary structure of the protein.

Active targeted nanoparticles: Preparation, physicochemical characterization and in vitro cytotoxicity effect.

In this study, the folate decorated biodegradable poly (lactide-co-glycolide) (PLGA) nanoparticles were developed for tumor targeting of anticancer agents. Due to the overexpression of the folate receptor on tumor surface, the folate has been efficiently employed as a targeting moiety for various anticancer agents to avoid their non-specific attacks on normal tissues and also to increase their cellular uptake within target cells. Folate conjugate PLGA was synthesized successfully and its chemical structure was evaluated by FTIR, DSC and (1)HNMR spectroscopy. PLGA-folate nanoparticles (PLGA-Fol NPs) were prepared by nanoprecipitation method, adopting PLGA as a drug carrier, folic acid as a targeting ligand and 9-nitrocampthotecin as a model anticancer drug. The average size and encapsulation efficiency of the prepared PLGA-Fol NPs were found to be around 115 ± 12 nm and 57%, respectively. In vitro release profile indicated that nearly 85% of the drug was released in 50 h. The in vitro intracellular uptakes of PLGA-Fol NPs showed greater cytotoxicity on cancer cell lines compared to non-folate mediated carriers.

Encapsulation in PLGA-PEG enhances 9- nitro-camptothecin cytotoxicity to human ovarian carcinoma cell line through apoptosis pathway.

Ovarian cancer is the fifth leading cause of the cancer-related death among women. 9-nitrocamptothecin (9-NC) is a water-insoluble derivative of camptothecin used for the treatment of patients with advanced ovarian cancer. Previous studies showed that the encapsulation of 9-NC in poly (lactic-co-glycolic acid, PLGA) nanoparticles increased the cytotoxic effect of the drug on different cancer cell lines. In the present study, the cytotoxic effects of 9-NC, 9-NC-loaded PLGA and PLGA-polyethylene glycol (PLGA-PEG) nanoparticles with varying degree of PEG (5, 10, and 15%) were evaluated on human ovarian carcinoma cell line. Furthermore, the mode of cell death induced by 9-NC and the optimized 9-NC-loaded PLGA-PEG nanoparticles on A2780 cell line were investigated. 9-NC incorporating nanoparticles were prepared by nanopercipitation method and their physicochemical characteristics were evaluated using standard methods. The results showed that activation of caspase-3 and -9 significantly increased by free 9-NC and PLGA-PEG loaded nanoparticles in A2780 cells. In contrast to the free drug which increased the activation of caspase-8, 9-NC-loaded PLGA-PEG nanoparticles did not alter the activation of caspase-8. Collectively, it appears that apoptosis induced by 9-NC incorporated in PLGA-PEG 5% occurred through the activation of caspase-9 rather than activation of caspase-8 which is the mediator of extrinsic pathway. Moreover, our results confirmed that 9-NC in nanoparticles at the level of gene expression potentiated down-regulation of Bcl-2, up regulation of Bax, and Smac/DIABLO leading to a decrease in mitochondrial membrane potential. Taken together, our results showed that 9-NC incorporated in PLGA-PEG 5% nanoparticles is able to induce apoptosis in A2780 human ovarian carcinoma cells and has the potential for the treatment of ovarian carcinoma.

Development and optimization of buspirone oral osmotic pump tablet.

The aim of the current study was to design a porous osmotic pump-based drug delivery system for controlling the release of buspirone from the delivery system. The osmotic pump was successfully developed using symmetric membrane coating. The core of the tablets was prepared by direct compression technique and coated using dip-coating technique. Drug release from the osmotic system was studied using USP paddle type apparatus. The effect of various processing variables such as the amount of osmotic agent, the amount of swellable polymer, concentration of the core former, concentration of the plasticizer, membrane thickness, quantum of orifice on drug release from osmotic pump were evaluated. Different kinetic models (zero order, first order and Higuchi model) were applied to drug release data in order to establish the kinetics of drug release. It was found that the drug release was mostly affected by the amount of NaCl as osmotic agent, the swellable polymer; hydroxy propyl methyl cellulose (HPMC), the amount of PEG-400 and cellulose acetate in the coating solution and thickness of the semipermeable membrane. The optimized formulation released buspirone independent of pH and orifice quantum at the osmogen amount of 42%, hydrophilic polymer of 13% and pore size of 0.8 mm on the tablet surface. The drug release of osmotic formulation during 24 h showed zero order kinetics and could be suggested that this formulation as a once-daily regimen improves pharmacokinetic parameters of the drug and enhances patient compliance.

Pharmacokinetic study and comparative bioavailability of two nelfinavir tablet formulations in Iranian healthy volunteers after a low-dose administration.

The objective of this study is to evaluate pharmacokinetic parameters, bioavailability of a potent HIV protease inhibitor, nelfinavir mesylate (NFV), following a single oral administration of 2 tablet formulations. A randomized, 2-way, crossover, bioequivalence study was conducted in 24 healthy male volunteers to compare 2 brands of nelfinavir 250 mg tablets, Nelfabiovir (Bakhtar Bioshimi, Iran) as test and Viracept (Roche, Germany) as reference product. Blood samples were collected at selected times during 12 h and plasma concentrations were determined with a sensitive and validated HPLC method involving a simple protein precipitation step. Individual pharmacokinetic parameters, t1/2, t1/2(abs), K, Ka, tmax, Cmax, Vd/F, Cl/F, AUC0-12 and AUC0- yen were determined from plasma concentration-time profiles for both formulations and were compared statistically. The analysis of variance (ANOVA) did not show any significant difference between the two formulations and 90% confidence intervals (CI) fell within the acceptable range, satisfying the bioequivalence criteria of the FDA. In vitro parameters of mean dissolution time (MDT) and time for 70% dissolution (T70) were also determined. There was no significant difference between these parameters for two dosage forms (p > 0.05). It was concluded that the two nelfinavir products are bioequivalent with respect to the rate and extent of absorption.

Oral bioavailability and pharmacokinetic study of cetrizine HCl in Iranian healthy volunteers.

The objective of the present study was to evaluate the pharmacokinetic parameters and bioavailability of a selective histamine (H1)-receptor antagonist, cetirizine hydrochloride (CTZ), following administration of a single oral dose of the drug. The properties of a test compound were compared with those of a reference product in a randomized cross-over study in 12 volunteers. Blood samples were collected at selected time intervals up to 24 h and plasma concentrations of CTZ were determined using a validated HPLC method. Pharmacokinetic parameters including T(1/2), T(1/2)(abs), K, K(a), T(max), C(max), V(d)/F, Cl/F, AUC(0-24), AUC (0-∞) and MRT were determined from plasma concentration-time profiles for tested products and found to be in good agreement with previous reports. The analysis of variance did not show any significant differences between the test and reference products. The confidence intervals for the ratio of C(max) (95-110%), AUC(0-24) (91-112%) and AUC(0-∞) (92-109%) for the test and reference products were within the acceptable interval of 80-125%. ANOVA assessment of logarithmically transformed data did not reveal any significant subject, period or sequence effects. It was, therefore, concluded that the two products were bioequivalent and could be used interchangeably.

Encapsulation of 9-nitrocamptothecin, a novel anticancer drug, in biodegradable nanoparticles: factorial design, characterization and release kinetics.

This study was aimed at developing a polymeric drug delivery system for a new and potent antitumor drug, 9-nitrocamptothecin (9-NC), intended for both intravenous administration and improving the therapeutic index of the drug. To achieve these goals, 9-NC loaded poly(DL-lactide-co-glycolide) (PLGA) nanoparticles were prepared by nanoprecipitation method and characterized. The full factorial experimental design was used to study the influence of four different independent variables on response of nanoparticle drug loading. Analysis of variance (ANOVA) was used to evaluate optimized conditions for the preparation of nanoparticles. The physical characteristics of PLGA nanospheres were evaluated using particle size analyzer, scanning electron microscopy, differential scanning calorimetry and X-ray diffractometry. The results of optimized formulations showed a narrow size distribution with a polydispersity index of 0.01%, an average diameter of 207+/-26 nm, and a drug loading of more than 30%. The in vitro drug release profile showed a sustained 9-NC release up to 160 h indicating the suitability of PLGA nanoparticles in controlled 9-NC release. Thus prepared nanoparticles described here may be of clinical importance in both stabilizing and delivering camptothecins for cancer treatment.

Liquid chromatographic quantitation of the lactone and the total of lactone and carboxylate forms of 9-nitrocamptothecin in human plasma.

Simple and sensitive high-performance liquid chromatography (HPLC) assays were developed and validated for the quantitation of the investigational anticancer drug 9-nitrocamptothecin (9-NC) as the lactone form and as the total of the lactone(I) and carboxylate(II) forms in human plasma. For the assay of lactone form (9NC-lac), the analytical method involved a protein precipitation step with adding a mixture of cold acetonitril-chloroform (5:1 (v/v), -20 degrees C) to plasma sample that stabilized the pH-dependent conversion of I to II. After evaporation under gentle stream of nitrogen gas (40 degrees C) the dry extract was dissolved in mobile phase (pH 5.5). For determination of the total of the lactone and carboxylate forms of the drug (9NC-tot), plasma samples were deproteinated with cold acetonitril (-20 degrees C) acidified with perchloric acid (5%), which resulted in the conversion of the carboxylate into the lactone form. After centrifugation the upper solvent was evaporated (nitrogen, 40 degrees C) and the dry extract was dissolved in mobile phase (pH 3.5). All separations were performed on a RP-C(8) column, using a mixture of acetonitril-water as eluent (pH 3.5 for total form and pH 5.5 for lactone form) and UV detection. The presented assay was linear over a concentration range of 25-1500 ng/ml with lower limit of quantitation of 25 ng/ml for both 9NC-tot and 9NC-lac. Within-run and between-run precision was always less than 7.5% in the concentration range of interest. The reported assay method showed good characteristics of linearity, sensitivity, selectivity and precision allowing applying in pharmacokinetic studies.

Synthesis and calcium antagonist activity of new 1,4-dihydropyridines containing nitrobenzylimidazolyl substituent in guinea-pig ileal smooth muscle.

New alkyl ester analogues of nifedipine, in which the ortho-nitrophenyl group of position 4 is replaced by 1-(4-nitrobenzyl)-5-imidazolyl or 2-methylthio-1-(4-nitrobenzyl)-5-imidazolyl substituent, were synthesized and evaluated as calcium-channel antagonists using the electrically induced contraction of guinea-pig ileal longitudinal smooth muscle. Our results demonstrate that all compounds inhibited the contractile response of guinea-pig ileum to electrical stimulation and the IC50 value of the most potent compounds 6a and 6f were significantly lower than that of nifedipine. Therefore, they are more potent than nifedipine.