AAPS PharmSci最新文献

Fundamental aspects of electrolyte chemistry were used to design an appropriate dissolution medium with the capacity to maintain sink conditions throughout the test. Dissolution of various bolus dosage forms was studied using USP Apparatus II at various stirring speeds. Complete dissolution of each drug in the designed medium was achieved, and there is evidence that such a dissolution test could be discriminating. This review details the development of potentially discriminating in vitro dissolution tests for veterinary boluses using USP Apparatus II and examines the potential role of such testing during product quality assessments, in the evaluation of postapproval manufacturing changes and for the establishment of the generic equivalence of veterinary products.

The potential inhibitory effects of 3 excipients (polyethylene glycol [PEG] 400, Pluronic P85, and vitamin E d-a-tocopheryl polyethylene glycol 1000 succinate [TPGS]) on the P-glycoprotein (P-gp) -mediated efflux of digoxin (DIG) and cytochrome P450 3A (CYP3A) -mediated metabolism of verapamil (VRP) have been examined in an in vitro permeability model. Experiments were conducted utilizing rat jejunal tissue mounted in diffusion chambers and included assessment of the serosal to mucosal (s to m) transport of DIG and the formation of norverapamil (NOR) during the mucosal to serosal transport of VRP, as measures of P-gp efflux and CYP3A metabolism, respectively. The presence of PEG at 1%, 5%, and 20% (wt/vol) reduced both the s to m flux of DIG (by 47%, 57%, and 64%, respectively, when compared to control) and the metabolism of VRP (by 54%, 78%, and 100%) in a concentration-dependent manner. P85 (0.1% wt/vol) significantly reduced s to m DIG flux by 47% and inhibited VRP metabolism by 42%. TPGS had insignificant effects on both metabolism and efflux at a concentration of 0.01% (wt/vol). The P-gp inhibitory effects of PEG and P85 were evident regardless of whether the excipient was added to the mucosal side, the serosal side, or both sides of the tissue. The current data suggest that inclusion of PEG and P85 as solubilizing agents during in vitro permeability assessment may have a significant impact on both drug metabolism and efflux processes. These compounds appear to exert their effects on P-gp primarily via direct transporter inhibition - or indirectly, through effects on buffer osmolarity, membrane fluidity, and/or mitochondrial toxicity and subsequent adenosine triphosphate (ATP) depletion.

In the present study, we evaluated polyethylenimine (PEI) of different molecular weights (MWs) as a DNA complexing agent for its efficiency in transfecting nondifferentiated COS-1 (green monkey fibroblasts) and well-differentiated human submucosal airway epithelial cells (Calu-3). Studying the effect of particle size, zeta potential, presence of serum proteins or chloroquine, it appeared that transfection efficiency depends on the experimental conditions and not on the MW of the PEI used. Comparing transfection efficiencies in both cell lines, we found that PEI was 3 orders of magnitude more effective in COS-1 than in Calu-3 cells, because Calu-3 cells are differentiated and secrete mucins, which impose an additional barrier to gene delivery. Transfection efficiency was strongly correlated to PEI cytotoxicity. Also, some evidence for PEI-induced apoptosis in both cell lines was found. In conclusion, our results indicate that PEI is a useful vector for nonviral transfection in undifferentiated cell lines. However, results from studies in differentiated bronchial epithelial cells suggest that PEI has yet to be optimized for successful gene therapy of cystic fibrosis (CF).

Mu opioid receptor (OPRM1), a member of the G-protein coupled receptor superfamily, mediates the analgesic and euphoric effects of opioid drugs. The sequences of OPRM1 cDNA and reported splice variants were used to search the public and Celera genomic databases. The matched sequences were analyzed to assemble an OPRM1 genomic contig. Human OPRM1 gene was estimated to span at least 90 kb in the chromosome 6q24-25 region. Four coding exons are separated by 3 introns. While intron 2 has only 773 bp, these databases for the first time provide the precise length of and other information about long introns 1 and 3, containing 50 and 27 kb, respectively. When a consensus exon/intron splice junction at the end of the coding exon 3 was not utilized, it may have resulted in continuous translation of the exon to yield the splice variant OPRM1A. The study did not identify human orthologs of other OPRM1 variants that had been reported for mouse OPRM1, although several proposed exons were found to be included in mouse genomic clones. Single nucleotide polymorphisms in the OPRM1 gene were also analyzed and summarized, which could provide potential polymorphic markers for molecular genetic studies.

Biological membranes normally restrict the passage of hydrophilic molecules. This impairs the use of a wide variety of drugs for biomedical applications. To overcome this problem, researchers have developed strategies that involve conjugating the molecule of interest to one of a number of peptide entities that are efficiently transported across the cell membranes. In the past decade, a number of different peptide families with the ability to cross the cell membranes have been identified. Certain of these families enter the cells by a receptor-independent mechanism, are short (10-27 amino acid residues), and can deliver successfully various cargoes across the cell membrane into the cytoplasm or nucleus. Surprisingly, some of these vectors, the SynB vectors, have also shown the ability to deliver hydrophilic molecules across the blood-brain barrier, one of the major obstacles to the development of drugs to combat diseases affecting the CNS.

Literature reports have suggested that hemodynamic response toward organic nitrates may be reduced in obese patients, but this effect has not been studied. We compared the mean arterial pressure (MAP) responses toward single doses of nitroglycerin (NTG, 0.5-50 micro g) in conscious Zucker obese (ZOB), Zucker lean (ZL), and Sprague-Dawley (SD) rats. NTG tolerance development in these animal groups was separately examined. Rats received 1 and 10 micro g/min of NTG or vehicle infusion, and the maximal MAP response to an hourly 30 micro g NTG IVchallenge dose (CD) was measured. Steady-state NTG plasma concentrations were measured during 10 micro g/min NTG infusion. The Emax and ED50 values obtained were 33.9 +/- 3.6 and 3.5 +/- 1.7 micro g for SD rats, 33.2 +/- 4.1 and 3.0 +/- 1.4 micro g for ZL rats, and 34.8 +/- 3.9 and 5.3 +/- 2.8 micro g for ZOB rats, respectively. No difference was found in the dose-response curves among these 3 groups (P >.05, 2-way ANOVA). Neither the dynamics of NTG tolerance development, nor the steady-state NTG plasma concentrations, were found to differ among these 3 animal groups. These results showed that ZOB rats are not more resistant to the hemodynamic effects of organic nitrates compared with their lean controls. Thus, the acute and chronic hemodynamic effects induced by NTG are not sensitively affected by the presence of obesity in a conscious animal model of genetic obesity.

Multidrug resistance-associated protein 1 (MRP1) was originally shown to confer resistance of human tumor cells to a broad range of natural product anticancer drugs. MRP1 has also been shown to mediate efflux transport of glutathione and glucuronide conjugates of drugs and endogenous substrates. An ortholog of MRP1 in the mouse has been cloned and characterized. Significant functional differences between murine and human MRP1 have been noted. Since drug disposition and pharmacology studies often are conducted in rats, there is a need to clone and characterize the rat ortholog of MRP1. We isolated a rat MRP1 (rMRP1) cDNA from rat brain astrocytes, characterized its coding sequences, and verified the transport activity of the protein expressed in MRP1 cDNA-transfected Madin-Darby canine kidney (MDCK) cells. Our results showed that rMRP1 has a coding sequence of 4599 bp, which predicts a polypeptide of 1533 amino acids with an apparent molecular weight of 190 kd by Western immunoblot analysis. rMRP1-transfected MDCK cells are capable of efflux transport of a fluorescent MRP1 marker - calcein - that is inhibitable by known MRP1 inhibitors, indomethacin, and MK571. Sequence analysis indicates that rMRP1 is more closely related to mouse MRP1 than human MRP1.

The goal of this study was to perform preformulation development of SY161 by using statistical design methods to understand the effects of buffer strength, NaCl concentration, and pH on conformation and stability of the protein. It was also important to elucidate interactions between these factors. A central composite design using a 2-level full-factorial study was performed. Secondary structure was evaluated using circular dichroism. Stability toward unfolding was investigated using high-sensitivity differential scanning calorimetry. Depegylation, aggregation, and protein loss were evaluated using SEC-HPLC with on-line light scattering, at time zero and after a 2-week stability study. Response surface plots clearly show optimal pH, NaCl, and buffer conditions. Interactions between pH and NaCl as well as pH and buffer concentration are observed. Tm is seen to be predictive of SY161 stability. Secondary structure changes were minimal and did not influence stability. Statistical design was very effective in providing an understanding of the effects of the formulation components on SY161 stability.

The goal of this special volume is to provide veterinary scientists with state-of-the art reviews in animal health and to inform human health scientists of the various challenges and collaborative opportunities associated with their animal health counterparts. The contributors are highly respected experts, providing invaluable insights into current issues and state-of-the-art advances within veterinary medicine.

Restenosis remains the major limitation of percutaneous transluminal angioplasty (PTA) and stenting in the treatment of patients with atherosclerotic disease. Catheter-based local delivery of pharmacologic agents offers a potential therapeutic approach to reducing restenosis and minimizing undesirable systemic side effects. However, the intramural retention of liquid agents is low. Therefore, to achieve a sustained and regional release of the therapeutic agent it must be encapsulated in nanoparticle carrier systems. The purpose of this study was to investigate the size dependence of the penetration of nanoparticles after local delivery into the vessel wall of the aorta abdominalis of New Zealand white rabbits. Two milliliters of a 0.025% fluorescence-labeled polystyrene nanoparticle suspension with diameters ranging from 110 to 514 nm were infused at 2 atm and at constant PTA pressure of 8 atm into the aorta abdominalis. After the infused segments were removed, the location of nanoparticles was visualized using confocal laser scanning microscopy and transmission electron microscopy. The study demonstrates a size-dependent nanoparticle penetration into the intact vessel wall. While nanoparticles of about 100 and 200 nm were deposited in the inner regions of the vessel wall, 514-nm nanoparticles accumulated primarily at the luminal surface of the aorta. The observations confirm that size plays a critical role in the distribution of particles in the arterial vessel wall. It is additionally influenced by the formation of pressure-induced infusion channels, as well as by the existence of anatomic barriers, such as plaques, at the luminal surface of the aorta or the connective elastic tissue.