Moisture induced changes

In an earlier section, the potential for a water-soluble substance to deliquesce was discussed. The emphasis here is on less obvious effects of moisture on solid dosage forms, and three associated areas that link to information presented earlier in this article are discussed 1) moisture-induced changes in the state of the solid 2) the effect of moisture on the performance of excipients in the manufacture of compressed tablets and 3) the chemical stability of bioactive agents alone and in combination with excipients. 

Rutqvist, J., C.-F.Tsang, and Y.Tsang, 2003. Analysis of Stress and Moisture-Induced Changes in Fractured Rock Permeability in the Yucca Mountain Drift Scale Test. Proceedings (to be published), GeoProc2003, Stockholm, Sweden, October 2003. 

ANALYSIS OF STRESS AND MOISTURE INDUCED CHANGES IN FRACTURED ROCK PERMEABILITY AT THE YUCCA MOUNTAIN DRIFT SCALE TEST... 

Another spectral change was found w hen a cast film of C AzoCgN+Br was annealed and then moistened (Figure 13). The type I spectrum of the as-cast film changed to the type V spectrum (the broken-line spectrum in Figure 13) after heating above its phase transition (115°C[22]), and then immediately shifted to the type III spectrum within 30 sec in a 75% humidity condition at room temperature. The type III state seemed to be another metastable state in the annealed film because the moisture induced isothermal transition from the type III to the type I required a long period (e.g. 13 hours even at 75% humidity). 

The conjugated forms of vitamin B6 appear to be less available than the six principal vitamers (102,104-106) a relative value of 58% has recently been suggested for PN-glycoside in humans (107). In addition, food processing and storage can induce changes that reduce the bioavailability of vitamin B6 (102). Thermal processing and low moisture conditions can induce reductive... 

Minimally, one should have a brief foreknowledge of the thermal and thermal/humidity solid-state stability of the API prior to initiation of excipient compatibility studies. These protocols should include investigation of stability at various temperature and humidity conditions and should always include information about both chemical stability and physical-form integrity of the API. Thermal and thermal moisture-induced solid-state chemical reactions are well known (5), with hydrolysis and oxidation being the most prevalent mechanisms of decay. Changes in physical form with thermal and... 

The strength of wood can be altered by environmental agents. The changes in pH, moisture, and temperature the influence of decay, fire, and UV radiation and the adsorption of chemicals from the environment can have a significant effect on strength properties. Environmentally induced changes must be considered in any discussion on the strength of treated or untreated wood. 

Resin Il/S-glass and Resin I/S-glass composites were tested in tension on unidirectional samples at 10° off axis. This test is considered to be sensitive to changes in interfacial bonding and is useful as a measure of moisture induced degradation. The data scatter for both systems is quite broad. Statistical... 

Biologically Induced Changes. All modern studies on the weathering of wood conclude that the final discoloration (graying) of wood in the presence of moisture is practically always due to growth of fungi on the wood surface (i, 2, 54, 65-69). The most frequently observed species is Aureobasidium... 

The periodic air-permeability measurements provide an excellent opportunity to study the evolution of TM-induced changes in fracture permeability, and TH-induced changes in fracture moisture content, throughout the four-year heating period and the subsequent cooling period. 

Figure 7 presents the calculated THM-induced changes in air permeability. These changes are caused by the combined effect of TH-induced changes in fracture moisture content (Figure 5) and TM-induced changes in fracture aperture (Figure 6). Near the heat source, permeability decreases mainly because of fracture closure, but is also affected by TH-induced wetting and drying. Away from the heat source, a zone of increased permeability has developed as a result of the opening of vertical fractures (Figure 7, near borehole section 74 4).

Flores-Ferntodez, G.M., Sold, R.J., Griebenow, K. (2009) The relation between moisture-induced aggregation and structural changes in lyophilized insulin. J Pharm Pharmacol, 61 (11), 1555-1561. 

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