1. Catanionic vesicles from an amphiphilic prodrug molecule: a new concept for drug delivery systems
Yue Jiang, Yuxia Luan,* Fei Qin, Lanxia Zhaoa and Zhonghao Li. RSC Adv., 2012, 2, 6905–6912
In vitro release studies. In vitro release studies of catanionic pharmacosomes were evaluated using a dynamic dialysis technique. A certain amount of catanionic pharmacosome dispersion was sealed in a dialysis membrane bag with molecular weight cut-off of ～3500 Da (Solarbio), and incubated at 37.0 ± 0.5 oC in different phosphate buffer solutions (PBS, pH 1.2, pH 5.8, pH 7.4) with a total volume of 55 mL. The phosphate buffer solutions were composed of desirable amounts of NaH2PO4, NaOH and water. The solution was continuously stirred at 100 rpm. At selected time intervals, 1 mL of solution was withdrawn from the release media and replaced by the same amount of fresh PBS. The solution was assayed by a UV spectrophotometer (TU-1810, Beijing Purkinje General Instrument Company Limited, China) at a wavelength of 366 nm, which is a typical absorbance peak of amlodipine. For comparison, the release of the pure amlodipine in the release medium was also investigated.
2. A simple and rapid method for chiral separation of amlodipine using dual chiralmobile phase additives
Jiaqi Xie, Qi Tan, Lin Yang, Shenzhi Lai, Shaotan Tang, Changqun Cai* and Xiaoming Chen*. Anal. Methods,2014, 6, 4408–4413
The technique of CMPAs has several advantages compared to CSPs. For instance, it employs achiral stationary phases, which are less expensive and more rugged than a chiral stationary phase. At the same time it allows more flexibility because a column can be used in conjunction with several additives at the same time or the chiral additive can be eluted out of the column with a strong solvent and a subsequent additive can be used. The Fell group, in particular, has produced the earliest example of the resolution of rac-amlodipine using a charged cyclodextrin additive in 52 min. Soon after, they have shown that amlodipine enantiomers could be separated within 23min on a C8 column using 20mmol L-1 SBE-β-CD. In 2010, Chen et al. demonstrated that the enantiomers of amlodipine besylate could be separated within 34 min using SBE-β-CD as the additive. To the best of our knowledge, there are no reports on the use of LC methods for shortening the enantiomeric retention time of amlodipine using CMPAs.
3. Simultaneous colorimetric detection of four drugs in their pharmaceutical formulations using unmodiﬁed gold nanoparticles as a probe
Karuna A. Rawat, Hirakendu Basu, Rakesh Kumar Singhal and Suresh Kumar Kailasa*. RSC Adv.,2015, 5, 19924–19932
To investigate the selectivity of the proposed method, aqueous solutions were spiked with 12 diﬀerent kinds of drugs (venlafaxine, imipramine, amlodipine, alfuzosin, indapamide, flucanazole, metformin, lisinopril, topiramate, cetrizine, levocetrizine and carbidopa, 100 mL, 0.1 mM) separately and then added 0.5 mL of unmodified Au NPs into the above solutions. The main reason to select the above drugs in this study is due to they have either similar structures or same mode of action. As shown in Fig. 1, the absorption spectra and color of unmodified Au NPs were changed only by the addition of four drugs (venlafaxine, imipramine, amlodipine, alfuzosin), confirming decrease in the interparticle distance of unmodified Au NPs, which yields both a substantial red-shift in the Plasmon band energy to longer wavelength and a red-to-blue color change. As a result, the characteristic SPR peak of unmodified Au NPs at 521 nm was red-shifted to 653, 695, 688, and 636 nm for venlafaxine, imipramine, amlodipine, and alfuzosin, respectively.