Current Issue : January - March Volume : 2015 Issue Number : 1 Articles : 4 Articles
The aim of this work is to analyze the particle characteristics, such as shape, roundness and size,\nof starches extracted from Florencia and waxy maize hybrids. The micromeritics and structural\nproperties of the samples were examined. The evaluation of flow properties, densification and\ncompression behaviour of the powders was carried out. Physical parameters and swelling characteristics\nof tablets containing Florencia and waxy maize starch were also studied. Starch samples\nwere compared with respect to their applicability as excipients in tablet formulation. The samples\nexhibited identical structure and similar particle characteristics. Maize starch extracted from the\nFlorencia dent hybrid showed better flowability and compressibility in tableting experiments,\nwhich resulted in better mechanical tablet properties. With regard to utilization as a disintegrant,\nFlorencia starch indicated rapid and intensive swelling and proved to act more effectively in the\nswelling process than waxy maize starch....
Substituted amylose (SA) polymers were produced from high-amylose corn starch by etherification of its hydroxyl groups with\nchloroacetate. Amorphous high-amylose sodium carboxymethyl starch (HASCA), the resulting SA polymer, was spray-dried\nto obtain an excipient (SD HASCA) with optimal binding and sustained-release (SR) properties. Tablets containing different\npercentages of SD HASCA and tramadol hydrochloride were produced by direct compression and evaluated for dissolution. Oncedaily\nand twice-daily SD HASCA tablets containing two common dosages of tramadol hydrochloride (100mg and 200mg), a freely\nwater-soluble drug, were successfully developed. These SR formulations presented high crushing forces, which facilitate further\ntablet processing and handling. When exposed to both a pH gradient simulating the pH variations through the gastrointestinal\ntract and a 40% ethanolmedium, a very rigid gel formed progressively at the surface of the tablets providing controlled drug-release\nproperties. These properties indicated that SDHASCA was a promising and robust excipient for oral, sustained drug-release, which\nmay possibly minimize the likelihood of dose dumping and consequent adverse effects, even in the case of coadministration with\nalcohol.\n1. Introduction...
Two major forms of human carboxylesterase (CES), CES1A and CES2, dominate the pharmacokinetics of most prodrugs such\nas imidapril and irinotecan (CPT-11). Excipients, largely used as insert vehicles in formulation, have been recently reported to\naffect drug enzyme activity. The influence of excipients on the activity of CES remains undefined. In this study, the inhibitory\neffects of 25 excipients on the activities of CES1A1 and CES2 were evaluated. Imidapril and CPT-11 were used as substrates\nand cultured with liver microsomes in vitro. Imidapril hydrolase activities of recombinant CES1A1 and human liver\nmicrosomes (HLM) were strongly inhibited by sodium lauryl sulphate (SLS) and polyoxyl 40 hydrogenated castor oil (RH40)\n[Inhibition constant (Ki) = 0.0460.01 mg/ml and 0.2060.09 mg/ml for CES1A1, and 0.1260.03 mg/ml and 0.7660.33 mg/ml,\nrespectively, for HLM]. The enzyme hydrolase activity of recombinant CES2 was substantially inhibited by Tween 20 and\npolyoxyl 35 castor oil (EL35) (Ki = 0.9360.36 mg/ml and 4.461.24 mg/ml, respectively). Thus, these results demonstrate that\nsurfactants such as SLS, RH40, Tween 20 and EL35 may attenuate the CES activity; such inhibition should be taken into\nconsideration during drug administration....
Titanium dioxide nanoparticles (TiO2) were synthesized and then dual-coated with silane coupling agent (KH-570) and OP-\n10 in sequence in order to be dispersed stably in water as lubricant additives. The tribological properties and the application\nperformance in Q235 steel machining of the nanoparticles as water-based lubricant additiveswere investigated on anMSR-10D fourball\ntribotester and on a bench drilling machine, respectively. Scanning electron microscope (SEM) and atomic force microscope\n(AFM) were used to analyze the worn surface. The results show that the surface-modified TiO2 nanoparticles can remarkably\nimprove the load-carrying capacity, the friction reducing, and anti wear abilities of pure water. The wear scar diameter and the\ncoefficient of friction of the water-based lubricating fluids with TiO2 nanoparticles decreased, and the thick deep furrows on the\nsurface of wear scar also decreased obviously with the increase of TiO2 concentration. The power consumption in drilling process\nwas lower and the cutting surface was smoother using the water-based lubricating fluids added TiO2 nanoparticles compared to\nthe fluid without addition. The reason for nanoparticles improving tribological properties of water based lubricating fluid might be\nthe formation of a dynamic deposition film during rubbing process according to analysis of the worn surface....
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