The development of new direct compression excipients should include a comprehensive and rapid determination of deformation properties. The aim of this study was to characterize StarLac, a new coprocessed compound for direct compression based on lactose and maize starch. For this purpose, the effects of the base materials (maize starch and spraydried lactose) were considered and the influence of the spray-drying process was investigated. This was performed by comparing the physical mixture of starch and spray-dried lactose at the same ratio as for StarLac. For analysis of the deformation behavior, the 3-D model and the Walker equation were applied; for verification, the Heckel equation and the pressure time function (a modified Weibull equation) were used. The advantages of StarLac are its good flowability depending on the spray-drying process, an acceptable crushing force due to its lactose content, its rapid disintegration depending on starch, and a brilliant fast release of an active ingredient, such as theophylline monohydrate. The volume-pressure deformation properties of StarLac were dependent on the lactose properties. Only at high maximum relative density (ϱ_rel,max) did the influence of starch cause a change in these properties. A network-like structure can be observed using scanning electron microscopy pictures. Overall, StarLac deformed plastically with a low portion of elasticity. The physical mixture exhibited a more elastic behavior than StarLac. However, the part of the powder that was irreversibly compressed was much lower than was observed for the single substances. This behavior is caused by an interaction between the components, which in StarLac is prevented by spray drying.

The objective of this study was to develop and evaluate a hydrogel vehicle for sustained release of growth factors for wound healing applications. Hydrogels were fabricated using ultraviolet photo-crosslinking of acrylamide-functionalized nondegradable poly(vinyl alcohol) (PVA). Protein permeability was initially assessed using trypsin inhibitor (TI), a 21 000 MW model protein drug. TI permeability was altered by changing the solids content of the gel and by adding hydrophilic PVA fillers. As the PVA content increased from 10% to 20%, protein flux decreased, with no TI permeating through 20% PVA hydrogels. Further increase in model drug release was achieved by incorporating hydrophilic PVA fillers into the hydrogel. As filler molecular weight increased, TI flux increased. The mechanism for this is most likely an alteration in protein/gel interactions and transient variations in water content. The percent protein released was also altered by varying protein loading concentration. Release studies conducted using growth factor in vehicles with hydrophilic filler showed sustained release of platelet-derived growth factor (PDGF-β,β) for up to 3 days compared with less than 24 hours in the controls. In vitro bioactivity was demonstrated by doubling of normal human dermal fibroblas numbers when exposed to growth factor-loaded vehicle compared to control. The release vehicle developed in this study uses a rapid and simple fabrication method, and protein release can be tailored by modifying solid content, incorporating biocompatible hydrophilic fillers, and varying protein loading concentration.

Restenosis remains the major limitation of percutaneous transluminal angloplasty (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 surgace 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.

The objective of the study was to develop an algorithm based on a pharmacokinetic-pharmacodynamic (PK/PD) modeling approach to quantify and predict cumulative cortisol suppression (CCS) as a surrogate marker for the systemic activity of inhaled corticosteroid therapy. Two Excel spreadsheets, one for single dose and another for steady-state multiple doses of inhaled steroids, were developed for predicting CCS. Four of the commonly used inhaled steroids were chosen for the purposes of simulation: fluticasone propionate (EP), budesonide (BUD), flunisolide (FLU), and triamcinolone acetonide (TAA). Drug-specific PK and PD parameters were obtained from previous single- and multiple-dose studies. In cases in which multiple-dose data were not available, the single-dose data were extrapolated. The algorithm was designed to calculate CCS based on 5 input parameters: name of drug, dose, dosing interval, time(s) of dosing, and type of inhaler device. In addition, a generalized algorithm was set up to calculate CCS based on clearance, volume of distribution, absorption rate, protein binding, pulmonary deposition, oral bioavailability, and unbound EC₅₀ of the corticosteroid of interest. The spreadsheet allowed predictions of CCS for single doses as well as steady-state conditions. A simple method has been developed that facilitates comparisons between various drugs and dosing regimens and has the potential to significantly reduce the number of comparative clinical trials to be performed for evaluating the short-term systemic activity of inhaled corticosteroids).

Guanine nucleotide-binding proteincoupled receptors (GPCRs) comprise large and diverse gene families in fungi, plants, and the animal kingdom. GPCRs appear to share a common structure with 7 transmembrane segments, but sequence similarity is minimal among the most distant GPCRs. To reevaluate the question of evolutionary relationships among the disparate GPCR families, this study takes advantage of the dramatically increased number of cloned GPCRs. Sequences were selected from the National Center for Biotechnology Information (NCBI) nonredundant peptide database using iterative BLAST (Basic Local Alignment Search Tool) searches to yield a database of ∼1700 GPCRs and unrelated membrane proteins as controls, divided into 34 distinet clusters. For each cluster, separate position-specific matrices were established to optimize sequence comparisons among GPCRs. This approach resulted in significant alignments between distant GPCR families, including receptors for the biogenic amine/peptide, VIP/secretin, cAMP, STE3/MAP3 fungal pheromones, latrophilin, developmental receptors frizzled and smoothened, as well as the more distant metabotrobic glutamate receptors, the STE2/MAM2 fungal pheromone receptors, and GPR1, a fungal glucose receptor. On the other hand, alignment scores between these recognized GPCR clades with p40 (putative GPCR) and pml (putative GPCR), as well as bacteriorhodopsins, failed to support a finding of homology. This study provides a refined view of GPCR ancestry and serves as a reference database with hyperlinks to other sources. Moreover, it may facilitate database annotation and the assignment of orphan receptors to GPCR families.

Recently it has been demonstrated that moderate heat treatment of Amphotericin B/deoxycholate solutions (HAmB-DOC) leads to a therapeutically interesting supramolecular rearrangement that can be observed by significant changes in light scattering, CD, and absorbance. In this study, we continue the investigation of the physical properties of this new form by evaluating the activity and kinetics of dissociation and dispersion of HAmB-DOC and AmB-DOC in saline, serum, and in model mammalian or fungal lipid biomimetic membrane vesicles. Stopped-flow spectrophotometry combined with singular value decomposition (SVD) and global analysis were used to resolve the components of this process. The dissociation kinetics for both states are complex, requiring multiexponential fits, vet in most cases SVD indicates only two significant changing species representing the monomer and the aggregate. The kinetic mechanism could involve dissociation of monomers from coexisting spectroscopically similar but structurally distinct aggregates or sequential rearrangements in supramolecular structure of aggregates. Rate constants and amplitudes of dissociation from aggregates to monomer in buffer, whole serum, 10% cholesterol, and ergosterol membrane vesicles are generally greater for AmB-DOC, demonstrating its greater kinetic instability. In addition, at comparable low concentrations, HAmB-DOC and AmB-DOC are nearly equally active at promoting cation selective permeability in ergosterol-containing membranes; however, HAmB-DOC is much less active against mammalian mimetic cholesterol-containing vesicles, despite a higher level of self-association, supporting previous observations that there exists a specific “toxic aggregate” structure.

Vascular nitrate tolerance is often accompanied by changes in the activity and/or expression of a number of proteins. However, it is not known whether these changes are associated with the vasodilatory properties of nitrates, or with their tolerance mechanisms. We examined the hemodynamic effects and vascular gene expressions of 2 nitric oxide (NO) donors: nitroglycerin (NTG) and S-nitroso-N-acetylpenicillamine (SNAP). Rats received 10 μg/min NTG, SNAP, or vehicle infusion for 8 hours. Hemodynamic tolerance was monitored by the maximal mean arterial pressure (MAP) response to a 30-μg NTG or SNAP bolus challenge dose (CD) at various times during infusion. Gene expression in rat aorta after NTG or SNAP treatment was determined using cDNA microarrays, and the relative differences in expression after drug treatment were evaluated using several statistical techniques. MAP response of the NTG CD was attenuated from the first hour of NTG infusion (P<.001, analysis of variance [ANOVA]), but not after SNAP (P>.05, ANOVA) or control infusion (P> .05, ANOVA). Student t-statistics revealed that 447 rat genes in the aorta were significantly altered by NTG treatment (P <.05). An adjusted t-statistic approach using resampling techniques identified a subset of 290 genes that remained significantly different between NTG treatment vs control. In contrast, SNAP treatment resulted in the up-regulation of only 7 genes and the downregulation of 34 genes. These results indicate that continuous NTG infusion induced widespread changes in vascular gene expression, many of which are consistent with the multifactorial and complex mechanisms reported for nitrate tolerance.

Ibuprofen and acetylsalicylic acid were studied by thermoanalytical methods: sublimation calorimetry, solution calorimetry, and with respect to solubility. Upon measuring the temperature dependences of the saturated vapor pressure, enthalpies of sublimation, ΔH_sub⁰ , as well as the entropies of sublimation, ΔH_sub⁰ , and their respective relative fractions in the total process were calculated. The Gibbs energy of solvation in aliphatic alcohols as well as the enthalpic and entropic fractions thereof were also studied and compared with the respective properties of model substances and other nonsteroidal antiinflammatory drugs (benzoic acid, diflunisal, flurbiprofen, ketoprofen, and naproxen). In all cases, enthalpy was found to be the driving force of the solvation process. Correlations were derived between Gibbs energy of solvation in octanol, ΔG_solv^Oct , and the transfer Gibbs energy from water to octanol, ΔG_tr⁰ . Influence of mutual octanol and water solubilities on the driving force of partitioning is discussed. An enthalpy-entropy-compensation effect in octanol was observed, and consequences of deviation from the general trend are also discussed.

Ibuprofen-gelatin micropellets were prepared by the cross-linking technique using formaldehyde. Spherical micropellets having an entrapment efficiency of 65% to 85% were obtained. The effect of core to coat ratio, speed of agitation, temperature, and volume of oil phase was studied with respect to entrapment efficiency, micropellet size, and surface characteristics. Fourier transform infrared spectroscopy and differential scanning calorimetric analysis confirmed the absence of any drug-polymer interaction. X-ray diffraction patterns showed that there is a decrease in crystallinity of the drug. The micromeritic properties of micropellets were found to be slightly changed by changing various processing parameters to give micropellets of good flow property. The in vitro release profile could be altered significantly by changing various processing parameters to give a controlled release of drug from the micropellets. The stability studies of the drug-loaded micropellets showed that the drug was stable at storage conditions of room temperature, 37°C, 25°/60% relative humidity (RH) and 45°/60% RH, for 12 weeks.

Feasibility studies were performed on the development of a novel process based on polyethylene glycol (PEG)-induced precipitation of proteins followed by vacuum drying in the presence of sugars to obtain dry protein powders. Apparent solubility of interferon alpha-2a (IFNα2a) was determined in the presence of various PEGs and the effect of solution pH, ionic strength, and temperature was investigated. IFNα2a precipitate was dried at a shelf temperature of 25°C at 100 mTorr either as it is or in the presence of mannitol and/or trehalose. The dried IFNα2a formulations were subjected to accelerated stability studies at 40°C (3 months), and the stability was compared with that of a similar lyophilized formulation. The results indicated that more than 90% of the protein could be precipitated using 10% wt/vol PEG the protein could be precipitated using 10% wt/vol PEG 1450 at pH 6.5 at a solution ionic strength of 71 mM. Vacuum drying of the precipitate only resulted in the formation of insoluble aggregates of IFNα2a; however, this was prevented by the addition of either mannitol or trehalose. The addition of excess mannitol resulted in low residual moisture content and better handling of the final dried product. Accelerated storage stability did not show any aggregation and showed less than 5% formation of oxidized IFNα2a in the dried formulation containing IFNα2a: trehalose: mannitol in a 1∶10∶100 wt/wt ratio upon storage at 40°C for 3 months. The stability of this vacuum dried formulation was comparable with that of a similar lyophilized formulation.