Excipients for direct compaction--an update.

Gerad K Bolhuis; N Anthony Armstrong

doi:10.1080/10837450500464255

Home/Archive/PubMed

PubMed · 16544915

Excipients for direct compaction--an update.

Gerad K Bolhuis·N Anthony Armstrong

View original source ↗Export metadata ↓

Abstract

In 1996, Bolhuis and Chowhan compiled a review of excipients that were used for the direct compaction of tablets. This article updates that review because since that time there has been considerable activity in this area. New single component and coprocessed filler-binders have been introduced. In addition, there have been advances in the understanding of how such substances act and hence how they can be optimally designed.

Explore related subjects

Calcium Compounds Cellulose Chemistry, Pharmaceutical Drug Compounding Excipients Lactose Oligosaccharides Polymers Powders Starch Journal Article Review

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

Gerad K Bolhuis, N Anthony Armstrong. 2006. Excipients for direct compaction--an update.. https://doi.org/10.1080/10837450500464255

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed2007

The formation of calcium lactate crystals is responsible for concentrated acid whey thickening.

The use of spray drying for dehydration of acid whey is generally limited by the appearance of uncontrolled thickening and solidifying of the whey mass during the lactose crystallization step. The origin of this physical change is still unknown and probably linked to complex interactions between physical properties and chemical composition of these products. To understand this phenomenon, we simulated the thickening of concentrated acid whey on a laboratory scale by measuring the flow resistance changes as a function of time and whey composition. The thickening process was characterized by an amplitude of torque and a lag time (induction time). Thickening of lactic acid whey concentrate occurred regardless of the presence of whey proteins or lactose crystals. Moreover, this work clearly demonstrated that the thickening process was due to the formation of filamentous structures corresponding to calcium lactate crystals and showed a large dependence on calcium and lactate contents, pH, and phosphate concentration.

Calcium Compounds↗

PubMed2006

Removal of manganese and zinc from Kahrizak landfill leachate using daily cover soil and lime.

The possibility of in situ removal of heavy metals found in leachate generated at municipal solid waste landfills was studied through amendment of daily cover soil. Kahrizak landfill, which receives the waste generated at Tehran, was selected as the source of leachate and soil samples. Manganese and zinc were selected in this study. The soil sample taken from the Kahrizak site contained about 17% clay, which was presumed to have significant capability for removing manganese and zinc. This capability was assumed to be enhanced further through the addition of lime and consequently to improve the potential for chemical precipitation of the selected metals. The in situ removal experiment was accomplished through a set of seven columns filled with the sampled soil with varying contents of lime (i.e., from 0% to 6% by dry weight). Fresh leachate of low pH was added to the columns on a daily basis. Concentrations of manganese and zinc were measured in the influent and effluent during 40 days when biological clogging resulted in a condition of almost no outflow in the columns. The results indicated a substantial increase in removal efficiency through the addition of lime to the daily cover soil. Desorption resulting from the low pH of fresh leachate occurs at later stages compared to the column with no lime addition.

Calcium Compounds↗

PubMed2006

The use of advanced diffraction methods in the study of the structure of a bioactive calcia: silica sol-gel glass.

Sol-gel derived calcium silicate glasses may be useful for the regeneration of damaged bone. The mechanism of bioactivity is as yet only partially understood but has been strongly linked to calcium dissolution from the glass matrix. In addition to the usual laboratory-based characterisation methods, we have used neutron diffraction with isotopic substitution to gain new insights into the nature of the atomic-scale calcium environment in bioactive sol-gel glasses, and have also used high energy X-ray total diffraction to probe the nature of the processes initiated when bioactive glass is immersed in vitro in simulated body fluid. The data obtained point to a complex calcium environment in which calcium is loosely bound within the glass network and may therefore be regarded as facile. Complex multi-stage dissolution and mineral growth phases were observed as a function of reaction time between 1 min and 30 days, leading eventually, via octacalcium phosphate, to the formation of a disordered hydroxyapatite (HA) layer on the glass surface. This methodology provides insight into the structure of key sites in these materials and key stages involved in their reactions, and thereby more generally into the behaviour of bone-regenerative materials that may facilitate improvements in tissue engineering applications.

Calcium Compounds↗