The Selection of a Pharmaceutical Salt—The Effect of the Acidity of the Counterion on Its Solubility and Potential Biopharmaceutical Performance

A roadmap for the selection of a pharmaceutical salt form for a development candidate is presented. The free base of the candidate did not have sufficient chemical stability for development. The initially selected salt form turned out to be undevelopable because it was unstable during scale-up synthesis and storage. The rationale for the new solid form screening and the criteria for selection are discussed. Before the final selection, the pH solubility profiles of the 2 new salts, a benzoate and a besylate, were compared. Atypical solubility behavior was observed for the benzoate salt in hydrochloric acid with and without normal saline. A scheme is proposed illustrating how the pKas of the counterion and active pharmaceutical ingredient, the medium composition, and final pH affect the solubility and solution equilibria of the 2 selected salt forms. This scheme also includes the equilibria between solution and solid phases in different pH ranges. The pharmaceutical importance of this research is that it sheds light on how the acidity of the counterion can affect the solubility of the selected salt form in the gastric environment. With a well-designed formulation strategy, this property potentially can be translated to optimal biopharmaceutical performance of the drug product.     

Bottom-Up and Top-Down Approaches to Explore Sodium Dodecyl Sulfate and Soluplus on the Crystallization Inhibition and Dissolution of Felodipine Extrudates

The objectives of this study were to explore sodium dodecyl sulfate (SDS) and Soluplus on the crystallization inhibition and dissolution of felodipine (FLDP) extrudates by bottom-up and top-down approaches. FLDP extrudates with Soluplus and SDS were prepared by hot melt extrusion, and characterized by polarized light microscopy, differential scanning calorimetry, and fourier transform infrared spectroscopy. Results indicated that Soluplus inhibited FLDP crystallization, and the whole amorphous solid dispersions (ASDs) were binary FLDP-Soluplus (1:3) and ternary FLDP-Soluplus-SDS (1:2:0.15～0.3 and 1:3:0.2～0.4) extrudates. Internal SDS (5%-10%) decreased glass transition temperatures of FLDP-Soluplus-SDS ternary ASDs without presenting molecular interactions with FLDP or Soluplus. The enhanced dissolution rate of binary or ternary Soluplus-rich ASDs in the nonsink condition of 0.05% SDS was achieved. Bottom-up approach indicated that Soluplus was a much stronger crystal inhibitor to the supersaturated FLDP in solutions than SDS. Top-down approach demonstrated that SDS enhanced the dissolution of Soluplus-rich ASDs via wettability and complexation with Soluplus to accelerate the medium uptake and erosion kinetics of extrudates, but induced FLDP recrystallization and resulted in incomplete dissolution of FLDP-rich extrudates. In conclusion, top-down approach is a promising strategy to explore the mechanisms of ASDs' dissolution, and small amount of SDS enhances the dissolution rate of polymer-rich ASDs in the nonsink condition.     

Pharmacokinetics and tissue distribution of crotonoside

1.?Crotonoside is a bioactive ingredient from Croton Herba with a strong antitumour activity. This study aimed to develop a highly sensitive and selective high-performance liquid chromatography (HPLC) method to quantify crotonoside in biological samples for pharmacokinetics and distribution studies.

2.?Protein precipitation by perchloric acid was used to separate crotonoside from the biological samples, and the recovery rates for crotonoside and the internal standard (luteoloside) were >80%. All calibration curves examining the crotonoside levels in plasma and tissues were linear (all correlation coefficients >?0.99).

3.?The response to crotonoside appeared to be dose disproportional to the maximum plasma concentration and the area under the time–concentration curve in plasma over the range of 12.5–50.0?mg/kg, and crotonoside was highly distributed in tissues after intravenous administration. The highest crotonoside level was detected in the liver (28.79?±?14.96?μg/g), whereas crotonoside was undetected in the brain.     

HPLC 法测定硫酸氢氯吡格雷片有关物质的不确定度评定

目的：对高效液相色谱法(HPLC)测定硫酸氢氯吡格雷片有关物质的不确定度进行评估,找出影响不确定度因素。方法：建立数学模型,对有关物质测定过程中各影响因素进行分析评估。结果：通过计算各变量的不确定度,合成不确定度,最终得出测量结果的扩展不确定度。结论：分析产生不确定度的主要来源,为有效控制该有关物质测定方法的准确性提供可靠的理论依据。     

HPLC-DAD/MS法测定抗风湿中成药中非法添加10种抗风湿化学成分

目的：建立检测抗风湿中成药中非法添加10种抗风湿化学成分的HPLC-DAD方法,并用MS/MS进行了化合物的归属分析。方法：用C18色谱柱(4.6mm×250mm,5um),以0.02mol/L乙酸铵(含0.05%乙酸)水溶液为流动相A,以乙腈为流动相B,梯度洗脱,波长240nm,流速1.0 ml/min,进行HPLC定性定量分析;再采用串联四级杆质谱的MRM模式检测,进行化合物归属分析,检测添加在中成药中的对乙酰氨基酚、甲氧苄啶、氨基比林、吡罗昔康、萘普生、双氯芬酸钠、醋酸泼尼松、吲哚美辛、保泰松、布洛芬10种化学成分。结果：10种抗风湿性化学成分液相检测的线性范围宽,相关性好,r≥0.9992,方法精密度的RSD为0.13%~0.45%;回收率在98.0%~100.9%之间;精密度、稳定性均符合要求;检测限为0.05~0.5 ug.ml_-1;定量限为0.1~1.8 ug.ml_-1。结论：本方法专属性强,操作简单,快捷,可作为中成药中非法添加以上10种抗风湿性化学成分的有效检测方法。     

高效液相色谱法测定二乙酰氨乙酸乙二胺注射液的有关物质

目的建立一种高效液相色谱法测定二乙酰氨乙酸乙二胺注射液有关物质.方法以ODS-C18为固定相,磷酸盐缓冲液(pH5.8)-乙腈-四氢呋喃(978:20:2)为流动相,检测波长为210 nm.结果该方法灵敏度高,精密度好.结论该法能有效检测二乙酰氨乙酸乙二胺有关物质.     

HPLC法测定金花消痤丸中栀子苷的含量

目的建立测定金花消痤丸中栀子苷含量的HPLC方法.方法色谱条件:Shim-Pack-C18柱,乙腈:水(15:85)为流动相,流速1.0ml·min-1,检测波长238 nm.结果栀子苷在5.17～51.7 mg·L-1浓度范围内与峰面积呈良好的线性关系(r=0.9999),平均回收率99.28%,RSD=0.64%.结论本法简便、准确、可控,可作为该产品的定量控制方法.     

HPLC法测定四制香附丸中橙皮苷的含量

目的建立高效液相色谱测定四制香附丸中橙皮苷含量的方法.方法以十八烷基硅烷键合硅胶为填充剂;乙腈-0.2%磷酸水溶液(21:79)为流动相;检测波长为284 nm.结果线性关系为Y=1.9848 X 2.1951,相关系数r=0.9995,线性范围在70.24～561.92 ng,平均回收率101.34%(n=6),RSD=1.08%.结论本法操作简便准确,可作为四制香附丸中橙皮苷含量的质量控制方法.     

HPLC法测定黄金搭档组合维生素片中VitA、VitE的含量

目的建立黄金搭档组合维生素片VitA和VitE含量测定方法.方法用高效液相色谱法进行分析.色谱柱为Symmetry-C18柱(5 μm,3.9×150 mm),流动相为甲醇-水(98:2),检测波长VitA326 nm、VitE 285 nm.结果峰面积与含量有良好的线性(rVitA=0.997 8,rVitE=0.999 9);重现性好(RSDVitA=0.33%,RSDvitE=0.29%);回收率高(XVitA96.9%,RSD=0.74%;XVitE98.0%,RSD=1.11%).结论方法稳定,简便易行,快速准确,可作为此片剂质量检测方法.     

A possible mechanism of low molecular weight protein tyrosine phosphatase (LMW-PTP) activity modulation by glutathione action during human osteoblast differentiation

Objective

Low molecular weight protein tyrosine phosphatases (LMW-PTPs) are a family of enzymes strongly involved in the regulation of cell growth and differentiation. Since there is no information concerning the relationship between osteoblastic differentiation and LMW-PTP expression/activity, we investigated its involvement during human osteoblast-like cells (hFOB 1.19) differentiation. It is known that LMW-PTP is regulated by an elegant redox mechanism, so we also observed how the osteoblastic differentiation affected the reduced glutathione levels.

Design

hFOB 1.19 cells were cultured in DMEM/F12 up to 35 days. The osteoblast phenotype acquisition was monitored by measuring alkaline phosphatase activity and mineralized nodule formation by Von Kossa staining. LMW-PTP activity and expression were measured using the p-nitrophenylphosphate as substrate and Western blotting respectively. Crystal violet assay determined the cell number in each experimental point. Glutathione level was determined by both HPLC and DNTB assays.

Results

LMW-PTP modulation was coincident with the osteoblastic differentiation biomarkers, such as alkaline phosphatase activity and presence of nodules of mineralization in vitro. Likewise LMW-PTP, the reduced glutathione-dependent microenvironment was modulated during osteoblastic differentiation. During this process, LMW-PTP expression/activity, as well as alkaline phosphatase and glutathione increased progressively up to the 21st day (p < 0.001) of culturing, decreasing thereafter.

Conclusions

Our results clearly suggest that LMW-PTP expression/activity was rigorously modulated during osteoblastic differentiation, possibly in response to the redox status of the cells, since it seems to depend on suitable levels of reduced glutathione. In this way, we pointed out LMW-PTP as an important signaling molecule in osteoblast biology and bone formation.