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The use of a wax-based vehicle is one approach to stabilize a drug which is susceptible to hydrolysis and/or oxidation. The drug used in the study, as a microfine powder, is dispersed in the wax mixture and encapsulated in a soft gelatin capsule. To ensure reproducibility of drug content uniformity and encapsulability of the soft gelatin capsule dosage form, optimal viscosity and lot to lot uniformity of the viscosity of the suspension are required. The objective of the study was to identify the critical processing factors which could affect the rheological behavior of the wax based vehicle. Rheological behavior of the vehicle at temperatures ranging from 15 to 90°C was evaluated using a CSL Rheometer equipped with parallel plates and a shear rate sweep mode, unless otherwise specified. Viscosity vs. temperature profiles of the vehicle were determined using the same conditions at different cooling rates ranging from 1.3 to 20°C per min. Three distinct regions of phase transition of the wax mixture can be seen in the Arrhenius plot: (i) a sol region at temperatures above 50°C, (ii) a transition of gel to sol at temperatures ranging from 30 to 45°C, and (iii) a gel region at temperatures below 30°C. The vehicle in a sol region behaved as a Newtonian fluid, indicating minimal interactions between the hydrocarbon chains of the vehicle. The vehicle in a gel region behaved thixotropic in nature, as indicated by a hysteresis loop. The shear rate had a more pronounced effect on the area of thixotropy than the shear time. The cooling rate had a pronounced effect on the resultant viscosity. At the same applied shear rate, the vehicle which was cooled at a faster rate, may cause a recrystallization of the wax mixture in different crystalline forms, resulting in a higher viscosity than the vehicle cooled at a slower rate. This effect was more pronounced when the shear was applied at a lower rate. The results of this study indicate that shear rate and cooling rate are the critical processing factors in controlling the viscosity of the final product and must be well controlled in the manufacturing procedure. [Copyright &y& Elsevier]

Introduction: Mandibular advancement splint (MAS) have become increasingly popular as alternatives to continuous positive airway pressure (CPAP) for the treatment of obstructive sleep apnea (OSA). However,the acceptance of MAS is limited to the efficacy rate of 50–70% and inability to predict which patients will respond to this treatment. To overcome this limitation,the temporary mandibular advancement titration was performed in mild to moderate OSA patients dsuring baseline polysomnography (PSG) Objective: To determine the efficacy of temporary mandibular advancement splint in mild to moderate OSA patients during baseline polysomnography (PSG). Materials and methods: This pilot study consisted of ten undiagnosed subjects with OSA symptoms. The Temporary mandibular advancement splint,fabricated at 50% and 70% of maximum jaw protrusion, had been delivered to all subjects before each subject underwent baseline PSG. After the first half of the night,five subjects had severe OSA (AHI>30) and CPAP titration was performed in this group,four subjects had mild to moderate OSA (AHI 5–30) and temporary mandibular advancement splint titration was performed in this group, one subjects was normal (AHI<5) and no any device was performed on this subject. Results: Mean apnea–hypopnea index (AHI) was significantly reduced from 20.60(SD 8.28) to 5.65(SD 4.49) after treatment with Temporary mandibular advancement splint (p <0.05).Three patients were considered treatment success and one patient was considered treatment failure as defined by AHI<5. Conclusion: This pilot study shows that it is possible to utilize temporary mandibular advancement splint titration in mild to moderate OSA patients during baseline PSG and these results suggest that temporary mandibular advancement splint can be used as a tool in predicting treatment response in terms of efficacy piro to oral appliance therapy by means of using mandibular advancement splint in treating OSA. Acknowledgements: This study is granted by dental department,Phramongkutklao hospital, Bangkok, Thailand. [Copyright &y& Elsevier]