Development dissolution characteristics

In order to determine the appropriate development conditions, we examined dissolution characteristics for resist films in the aqueous alkaline developers by measuring film thickness as a function of development time. In Figure 7, dissolution characteristics for the new resist before and after exposure to KrF excimer laser are compared with those for the styrene resin matrix. 

The dissolution characteristics of oral formulations should be evaluated over the physiologic pH range of 1.2-6.8 [1.2-7.5 for modified release (MR) formulations]. During method development, it may be useful to measure the pH before and after a run to see if the pH changes during the test,... 

This system has been reported to show good photosensitivity (—100 mJ/cm2 in the 230-300 nm range) with extremely high contrast. Values of 7 > 5 were observed, compared to 2 for conventional systems. Chandross et al. believe the high contrast stems from the unusual dissolution characteristics of the resist in that the basic "developer" appears only to "prime" the irradiated regions for subsequent development in the aqueous rinse. The resist formulation is essentially aliphatic in nature and would be expected to be less stable to dry etching environments than the aromatic-based novolac resin materials. 

An rvrVC should be evaluated to demonstrate that predictability of in vivo performance of a drug product from its in vitro dissolution characteristics is maintained over a range of in vitro dissolution release rates and manufacturing changes. Since the objective of developing an IVIVC is to establish a predictive... 

The problem of alteration in dissolution characteristics on aging is typical to gelatin-based dosage forms. It is routinely faced by the manufacturers and, therefore, is a matter of concern. Fortunately, a lot of understanding has been developed over the period, since the time the problem was first recognized. The purpose of this article is to put the problem in the right perspective based on recent developments and the review of the reports in literature. 

Sayed HA, Price JC. Tablet properties and dissolution characteristics of compressed cellulose acetate butyrate microcapsules containing succinyl sulfathiazole. Drug Development and Industrial Pharmacy. 1986 12 577-587. 

The dissolution of Novolak resins in solvents is an important process in many semiconductor applications [17, 18], Hence, it becomes necessary to understand the dissolution characteristics of Novolaks. Novolak resins, as the world s oldest synthetic materials, play a remarkable role in today s semiconductor industry. Their advantages are in their non-swelling nature, aqueous-base developability and etching resistance [19, 20]. 

Aqueous Base Dissolution Characteristics. Films of these copolymers were cast on 4" Si wafers and baked at 130°C for 1 minute to remove the casting solvent, ethyl lactate. The film thickness (approximately 1.0 jim) was measured on a Tencor Alphastep. The dissolution rates of these films were then measured by immersion in aqueous tetramethylammonium hydroxide (TMAH) solution (at 23 °C) using a Perkin-Elmer 5900 Development Rate Monitor. The dissolution rates were then measured by immersion in a variety of TMAH solutions of increasing normality (0.14,0.26,0.30,0.60 and 1.0 N). 

Through these hot tests, information of dissolution characteristics dependent on many factors and nuclides behavior in the solvent extraction process have been obtained. In addition, PNC has developed the Np co-extraction process with U and Pu to enhance non-proliferation aspect. 

The development of practical 157-nm resists brings its share of challenges. Achieving the proper dissolution characteristics in polymer systems containing... 

Hughey JR, Keen JM et al (2013) The use of inoiganic stdts to improve the dissolution characteristics of tablets containing Soluplus-based solid dispersions. Eur J Pharm Sci 48 758-766 Iyer R, Hegde S et al (2013) The impact of hot melt extrusion and spray drying on mechanical properties and tableting indices of materials used in pharmaceutical development. J Pharm Sd... 

The aim of this approach [11] was to develop a simple, nevnal network model of ketoprofen dissolution from solid dispersions (SD) and physical mixtures (PM). This model could be an aid in prospective formulation of solid dispersions with ketoprofen, predicting its dissolution characteristics from unknown pharmaceutical formulations. The seven inputs were chosen for the model formulation of SD or PM, SD previously mixed or not, method of preparation (evaporation or melting), cooling on ice or ambient temperature, amount of ketoprofen in SD or PM formulation, carrier connectivity index and time of dissolution test the output was the dissolved ketoprofen at a specified time in the input. 

Laswell et al., 1971 Arato, 1974). All were prone to excessive dissolution and only one had adequate strength and film thickness. Their working characteristics were found to be unduly sensitive to changes in temperature and humidity (Simmons, D Anton Hudson, 1968). All were inferior to conventional zinc phosphate cements. No further development of these cements has taken place, nor is it likely that interest in them will be revived. The modem water-activated glass-ionomer cement has filled this niche and has vastly superior properties including adhesion to tooth material. 

For PMMA/additive dissolutions, it was not possible to identify any additive characteristic mass peaks, either by direct laser desorption or with matrix-assistance (dithranol, DHBA or sinapinic acid, 4-hydroxy-3,5-dimethoxy-cinnamic acid). This has again been ascribed to very strong interaction between PMMA and additives, which suppresses desorption of additive molecules. Also, partial depolymerisation of pho-tolytically labile PMMA by laser irradiation may play a role, which leads to saturation of the detector by PMMA fragment-ions and disappearance of additive mass peaks below noise level. Meyer-Dulheuer [55] has also reported MALDI-TOFMS analysis of a coating/2-ethylhexyldiphenylphosphate sample. Quantitative determination of the additives by means of MALDI-ToFMS proved impossible. Possibly the development of reproducible (automated) sample handling procedures or thin films might overcome this problem. 

Within the realm of physical reality, and most important in pharmaceutical systems, the unconstrained optimization problem is almost nonexistent. There are always restrictions that the formulator wishes to place or must place on a system, and in pharmaceuticals, many of these restrictions are in competition. For example, it is unreasonable to assume, as just described, that the hardest tablet possible would also have the lowest compression and ejection forces and the fastest disintegration time and dissolution profile. It is sometimes necessary to trade off properties, that is, to sacrifice one characteristic for another. Thus, the primary objective may not be to optimize absolutely (i.e., a maxima or minima), but to realize an overall pre selected or desired result for each characteristic or parameter. Drug products are often developed by teaching an effective compromise between competing characteristics to achieve the best formulation and process within a given set of restrictions. 

On the basis of this comparison study, at present, it is still difficult to adopt a universal selective sequential dissolution procedure, which may be used everywhere and be suitable for all soils with diversified physical, chemical and mineralogical properties. The application of the SSD procedure must consider individual soil characteristics, such as soil type and properties. The two typical SSD procedures were developed to address soils formed in two climates. The Rehovot procedure was developed to be suitable for the calcareous soils in arid and semi-arid zone soils, whereas the Bonn procedure was created to primarily handle the acid and neutral soils in humid zones. In general, the Bonn procedure appears to be unsuited for calcareous soils in arid and semi-arid zones. The Rehovot procedure has limitations in handling acid and neutral soils, especially forest soils with higher content of organic matter. 

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