PubMed · 16845562
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Neil H Hyman. 2006. Justifiable conclusions?. https://doi.org/10.1007/s10350-006-0623-1
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In this study hydroxypropylmethylcellulose (HPMC) and sodium carboxymethylcellulose (NaCMC) were used as polymeric carriers to improve controlled release performances of matrix tablets containing a soluble drug. The drug release behaviour of the systems containing these two polymers mixture and each material separately was investigated. To evaluate the effect of the dissolution medium pH, on the drug release performance, release tests were conducted at pH 1, 4.5 and 6.8. In vitro release studies demonstrated that the mixture of the two cellulose derivatives enables a better control of the drug release profiles at pH 4.5 and at 6.8 both in term of rate and mechanism. Texture analysis on the swollen tablets helps to understand drug release kinetic and mechanism. In fact, the results obtained confirm that a gel, which is characterized by high strength and consistence is less susceptible to erosion and chains disentanglement and the drug release mechanism is mainly governed by diffusion. On the contrary, gels, which show a low strength and texture, have low resistance to the fluid erosion action and the release of the active molecule is manly due to polymer relaxation and chains disentanglement moving the drug delivery kinetic towards an erosion/relaxation mechanism.
Several organic compounds of high molecular weight present in soil interact with selenium and may act as active binding agents affecting its availability in soil, and, consequently, selenium uptake by plants. This study is aimed at investigating the effects of polysaccharides on selenium speciation in soil and on selenium absorption by Lactuca sativa L. plants. Three-week-old seedlings were transplanted into pots filled with soil, and sodium selenite at rates of 1.5 and 5mgSekg(-1) of soil, or sodium selenate at a rate of 1.5mgSekg(-1) of soil were applied. Carboxymethylcellulose (CMC) was added to the soil at rates of 0, 3 and 30mgkg(-1) of soil. After 48 and 110d from transplanting plants were harvested, separated into root and shoot, and fresh and dry matter weights were recorded. Total selenium was determined in both soil and plant samples. A sequential extraction was used to investigate the different Se oxidation states and assess the availability of Se in soil after the final harvesting. Both selenite and selenate were absorbed by roots, but plants amended with Se(VI+) showed higher selenium concentration than plants amended with Se(IV+). Selenite appears to be less mobile than selenate both in soil and plants. The addition of carboxymethylcellulose to soil decreased the amount of selenium absorbed by plants. CMC interacted with Se, making it less mobile as evidenced by the increase in the insoluble fractions. The insoluble Se forms in soil may represent environmental Se sinks potentially available for plants if the substrate is re-used for subsequent growth cycles and selenium species are mobilized as a result of biological and chemical processes.
OBJECTIVE: To evaluate the cost-effectiveness of an adhesion prevention strategy compared to routine care, in which no adhesion prevention measures are taken, through a decision analysis model in the clinical setting of patients undergoing radical hysterectomy and pelvic lymphadenectomy for Stage IB cervical cancer. METHODS: A decision analysis model compared two strategies to manage the risk of adhesion-related morbidity following radical hysterectomy for Stage IB cervical cancer: (1) routine care with no adhesion prevention measures, and (2) the intervention strategy with a HA-CMC anti-adhesion barrier. The cost-effectiveness of each strategy was evaluated from the perspective of society and that of a third party payer. RESULTS: From the perspective of society, the HA-CMC strategy had an overall cost per patient of $1932 and effectiveness of 7.901 QALYs and dominated the routine care strategy, which had a cost per patient of $3043 and effectiveness of 7.805 QALYs. From the perspective of a third party payer, the HA-CMC strategy had an overall cost per patient of $1247 and effectiveness of 7.987 QALYs and dominated the routine care strategy, which had a cost per patient of $1629 and effectiveness of 7.970 QALYs. A series of one-way sensitivity analyses confirmed the robustness of the model. CONCLUSIONS: Under a conservative set of clinical and economic assumptions, an adhesion prevention strategy utilizing a HA-CMC barrier in patients undergoing radical hysterectomy for Stage IB cervical cancer is cost-effective from both the perspective of society as a whole and that of a third party payer.