Subacute oral toxicity study of diethylphthalate based on the draft protocol for “Enhanced OECD Test Guideline no. 407”

We performed a 28-day repeated-dose toxicity study of diethylphthalate based on the draft protocol of the “Enhanced OECD Test Guideline 407” to investigate whether it has endocrine-mediated properties according to this assay. Diethylphthalate was orally administered to SD rats at doses of 0, 40, 200, and 1,000 mg/kg/day for at least 28 days, but no endocrine-mediated effects were detected based on any of the parameters examined, suggesting that diethylphthalate does not possess endocrine properties according to this assay.     

Acute P-407 Administration to Mice Causes Hypercholesterolemia by Inducing Cholesterolgenesis and Down-Regulating Low-Density Lipoprotein Receptor Expression

Purpose Poloxamer 407 (P-407) is a chemical that induces a dose-controlled dyslipidemia in mice. Our aim was to determine the acute effects of P‐407 treatment on the mechanisms that influence hepatic cholesterol homeostasis. Methods We measured lipid levels in plasma and liver samples from control and P-407-treated mice (24 h post-i.p. injection of 0.5 g kg⁻¹ of P-407 or saline for the control mice). We measured acyl-coenzyme A:cholesterol acyltransferase (ACAT) and 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase activities in liver microsomes. The protein expression of ACAT2, scavenger receptor class B, type I (SR-BI), ATP-binding cassette transporter A1 (ABCA1), ATP-binding cassette transporter G8 (ABCG8), low-density lipoprotein receptor (LDLr), and actin was measured by immunoblot. Results We found an increase in plasma cholesterol and triglyceride levels as well as increased hepatic cholesteryl esters (CE) in P-407-treated mice. The hepatic ACAT microsomal activity and ACAT2 protein expression were not altered by P-407. The protein expression of the LDLr was decreased in the livers of P-407-treated mice. This decrease was specific, because the expression of the SR-BI was unchanged. The P-407-induced hypercholesterolemia was accounted for by increased activity and protein expression of HMG-CoA reductase. ATP-binding cassette transporters A1 and G8 protein expression were not significantly different in P-407-treated mice compared to controls. Conclusions The increased hepatic CE levels, following P-407 treatment, was neither related to an up-regulation of ACAT2 nor enhanced SR-BI expression. Hypercholesterolemia was associated with an up-regulation of both the protein expression and activity of HMG-CoA reductase and decreased LDLr expression.     

Effect of poloxamer on the dissolution of felodipine and preparation of controlled release matrix tablets containing felodipine

The effects of poloxamer and HPMC on the dissolution rate of felodipine were investigated and a felodipine controlled release tablet was developed by increasing the water solubility of felodipine and using swelling polymer to control release rate. Milling of felodipine slightly increased the dissolution rate of felodipine when compared with physical mixture. XRD results indicated that felodipine remained in the crystalline form even after co-milling with poloxamer. Improved dissolution rates after co-milling with HPMC and poloxamer were due to both solubilization effect of polymer and milling. The effect of poloxamer on dissolution rate was more significant than that of HPMC. Based on increased solubility of felodipine in the presence of poloxamer, it was concluded that the improved dissolution rate of felodipine was mainly due to a high local concentration of poloxamer around felodipine. Controlled release felodipine tablets were prepared using poloxamer as a solubilizing agent and Carbopol as a controlled release matrix.     

美洛昔康温敏性水凝胶的制备及质量控制

目的:制备美洛昔康温敏性水凝胶并建立其质量控制方法。方法:以泊洛沙姆P407、P188为基质制备温敏性水凝胶;采用紫外分光光度法测定其中主药的含量。结果:所制制剂为水溶性淡黄色或淡黄绿色透明凝胶,鉴别、检查均符合2005年版《中国药典》中的相关规定;美洛昔康检测浓度的线性范围为1.956~19.56mg·L-1(r=0.999 7);平均回收率为98.42%(RSD=1.53%)。结论:本制剂制备工艺简单,质量可控。     

吡喹酮水凝胶栓剂的含量测定

目的:制备吡喹酮水凝胶栓剂,并建立其含量测定方法。方法:用紫外分光光度法测定凝胶栓剂中吡喹酮的含量。结果:吡喹酮在0.2￣1.0mg/ml(r=0.9999)浓度范围内呈良好线性关系。平均加样回收率和相对标准偏差(RSD)为(102.44±0.69)%。结论:该处方设计合理,制备工艺可靠,质量稳定。     

左氧氟沙星热敏型眼用凝胶的研制及体外释放研究

目的:制备左氧氟沙星热敏型眼用凝胶,并对其体外释放行为进行考察。方法:以泊洛沙姆407为热敏型材料制备左氧氟沙星眼用凝胶,根据胶凝温度筛选泊洛沙姆407的最佳处方浓度,采用无膜溶出模型对该制剂的体外释放行为进行考察。结果:左氧氟沙星检测浓度线性范围为3～11μg/ml(r=0.9991,n=6),回收率为99.62%;泊洛沙姆407在处方中的最佳浓度为18%;药物释放呈零级动力学特征,释放量取决于凝胶溶蚀量。结论:该制剂制备方法简单,用药剂量易于控制,极具开发前景。     

A polymeric micellar carrier for the solubilization of biphenyl dimethyl dicarboxylate

A polymeric micelle drug delivery system was developed to enhance the solubility of poorly-water soluble drug, biphenyl dimethyl dicarboxylate, DDB. The block copolymers consisting of poly(D,L-lactide) (PLA) as the hydrophobic segment and methoxy poly(ethylene glycol) (mPEG) as the hydrophilic segment were synthesized and characterized by NMR, DSC and MALDI-TOF mass spectroscopy. The size of the polymeric micelles measured by dynamic light scattering showed a narrow monodisperse size distribution with the average diameter less than 50 nm. The MW of mPEG-PLA, 3000 (MW of mPEG, 2 K; MW of PLA, 1 K), and the presence of hydrophilic and hydrophobic segments on the polymeric micelles were confirmed by MALDI-TOF mass spectroscopy and NMR, respectively. Polymeric micelle solutions of DDB were prepared by three different methods, i.e. the matrix method, emulsion method and dialy-sis method. In the matrix method, DDB solubility was reached to 13.29 mg/mL. The mPEG-PLA 2K-1 K micelle system was compared with the poloxamer 407 micelle system for their critical micelle concentration, micelle size, solubilizing capacity, stability in dilution and physical state. DDB loaded-polymeric micelles prepared by the matrix method showed a significantly increased aqueous solubility (>5000 fold over intrinsic solubility) and were found to be superior to the poloxamer 407 micelles as a drug carrier.     

Protective role of Hemidesmus indicus R. Br. root extract against Salmonella typhimurium-induced cytotoxicity in Int 407 cell line

The present investigation deals with the effect of the chloroform fraction composed of sterols and fatty acids isolated from Hemidesmus indicus root extract (CHI) on Salmonella enterica serovar Typhimurium (S. typhimurium)-induced cytotoxicity in a human intestinal epithelial cell line (Int 407). The optimum dose was fixed as 100 microg/mL for CHI against S. typhimurium, which was quite safe for Int 407 cells as the CD(50) concentration (50% cell death) of CHI was determined to be 500 microg/mL in the Int 407 cell line. CHI-treated S. typhimurium were 10-fold less cytotoxic and 40% less adherent to host cells than wild-type. Treatment of CHI significantly abrogated the invasion ability to 10- to 15-fold in S. typhimurium. The cells infected with CHI-treated S. typhimurium had a comparable viability to uninfected cells in the epithelial cell detachment assay. Immunofluorescence showed the CHI-treated bacteria were unhealthy and shrunken rods in comparison with the wild-type bacteria; those were firmly attached and invaded to deceased and hypertrophoid Int 407 cells. Transmission electron micrographs of Int 407 cells infected with wild bacteria showed a coat of adherent and invaded bacteria completely occupying the cytoplasm with characteristic Salmonella-containing vacuoles (SCV). Both necrotic and apoptotic type of cell death were observed in cells infected with wild-type bacteria, whereas most of the cells infected with treated bacteria were normal in morphology and a few had invaded bacteria, but the typical proliferated SCV was not observed in cells infected with CHI-treated S. typhimurium. In summary, the sterols and fatty acids present in CHI may be capable of taming S. typhimurium by suppressing its cytotoxic activity in an intestinal epithelial cell line.