The Influence of Cellulosic Polymer's Variables on Dissolution/Solubility of Amorphous Felodipine and Crystallization Inhibition from a Supersaturated State.

The collective impact of cellulosic polymers on the dissolution, solubility, and crystallization inhibition of amorphous active pharmaceutical ingredients (APIs) is still far from being adequately understood. The goal of this research was to explore the influence of cellulosic polymers and incubation conditions on enhancement of solubility and dissolution of amorphous felodipine, while inhibiting crystallization of the drug from a supersaturated state. Variables, including cellulosic polymer type, amount, ionic strength, and viscosity, were evaluated for effects on API dissolution/solubility and crystallization processes. Water-soluble cellulosic polymers, including HPMC E15, HPMC E5, HPMC K100-LV, L-HPC, and MC, were studied. All cellulosic polymers could extend API dissolution and solubility to various extents by delaying crystallization and prolonging supersaturation duration, with their effectiveness ranked from greatest to least as HPMC E15 > HPMC E5 > HPMC K100-LV > L-HPC > MC. Decreased polymer amount, lower ionic strength, or higher polymer viscosity tended to decrease dissolution/solubility and promote crystal growth to accelerate crystallization. HPMC E15 achieved greatest extended API dissolution and maintenance of supersaturation from a supersaturated state; this polymer thus had the greatest potential for maintaining sustainable API absorption within biologically relevant time frames.

[An experimental study on the relationship between the orthodontic tooth movements and menstrual cycle].

PURPOSE: The purpose of this study was to explore the relationship between the menstrual cycle and orthodontic tooth movement. METHODS: A Wistar rat model was established to apply orthodontic activation during different stages of the estrous cycle. The distances of the tooth movements were measured and the serum estradiol level was detected by radioimmunoassay. The data of each group was analyzed with SPSS11.0 software package for Student-Newman-Keuls(S-N-K)test and one way ANOVA test. And cosinor-rhythmometry method was used for chronobiologic analysis to show the rhythmic change of the serum estradiol level. RESULTS: There was a 5-day rhythm of the rat serum estradiol during the estrous cycle. The distances of orthodontic tooth movement were different at various stages. Teeth moved fastest in the estrus while the serum estradiol was lowest (P<0.05), the distance of tooth moved was (2.10+/-0.14)mm. And teeth moved slowest in the proestrus while the serum estradiol was highest (P+/-0.05), the distance of tooth moved was (1.79+/-0.03)mm. Totally, orthodontic activation increased the serum estradiol level without disturbing its fluctuating rhythm. CONCLUSION: It was inferred that female patients may have an optimal opportunity of orthodontic activation for rapid tooth movement, which should be applied on a few days before the menorrhea in order to move the teeth rapidly.

[Changes of sarco(endo)plasmic reticulum Ca2+-Mg2+-ATPase activity of cultured myoblast induced by cyclic stretch].

OBJECTIVE: To evaluate the effect of stretch on sarco(endo)plasmic reticulum Ca2+-Mg2+ ATPases activity and mRNA level and study the remodeling reaction of muscle in a variety of mechanical environments. METHODS: Myoblast from maxillofacial skeletal muscle of one-week-old male Sprague-Dawley rat was cultured and stretched cyclicly using a four-point bend device. Inorganic Phosphorus test was used to compare the activity of Ca2+-Mg2+ ATPases of myoblast before and after stretch. RT-PCR was also used to observe the Ca2+-Mg2+ ATPases mRNA level. RESULTS: The activity of Ca2+-Mg2+ ATPases of myoblast down regulated significantly in 4 hours. During the period of 8 hours to 24 hours, up-regulation followed then returned to control level at the 48 hour point. RT-PCR showed that Ca2+-Mg2+ ATPases mRNA level were elevated by stretch, particularly at 2 hour and 48 hour point. CONCLUSION: The results suggested a transcriptional control of Ca2+-Mg2+ ATPases activity was involved in the muscle remodeling process induced by stretch.