Electrostatically bound lanreotide peptide - gold nanoparticle conjugates for enhanced uptake in SSTR2-positive cancer cells.

Lanreotide peptide (LP) has high affinity to somatostatin receptors like SSTR2 and is commonly used in the treatment of neuro-endocrine tumors. The main objective of this study is to target gold nanoparticles (AuNPs) towards SSTR2-positive cancer cells using lanreotide peptide (LP) as the targeting agent for enhanced tumor uptake and antitumor activity. pH mediated changes in the surface potential of LP and AuNP is used to prepare electrostatically bound AuNP-LP complexes. AuNP-LP complex formation was demonstrated by UV-Visible spectroscopy, surface potential, dynamic light scattering (DLS), small angle X-ray scattering and HR-TEM. Confocal microscopy and flow cytometric studies show that AuNP-LP complex has higher cellular uptake in SSTR2 expressed cancer cells (MCF-7 and AR42J) than in CHO cells. The enhanced cellular uptake of LP coated AuNPs lead to ~1.5 to 2-fold GSH depletion and enhanced ROS generation in MCF-7 cells. The preferential cytotoxicity of the AuNP-LP complex towards MCF-7 and AR42J cells, as revealed by MTT assay, is consistent with the increased cellular uptake. Our studies demonstrate that LP coated AuNP can be used as an effective platform to selectively target SSTR2 positive cancer cells for combination therapy approaches involving gold nanoparticles.

Reversed-phase ultra-performance liquid chromatographic method development and validation for determination of impurities related to torsemide tablets.

A simple RP-ultra-performance LC method was developed and validated for determination of impurities related to torsemide tablets. The rapid method provided adequate separation of all known related impurities and degradation products. Separation was achieved on a Zorbax SB-C18 column (50 x 4.6 mm id, 1.8 microm particle size) with binary gradient elution, and detection was performed at 288 nm. The drug product was subjected to oxidative, hydrolytic, photolytic, and thermal stress conditions to prove the specificity of the proposed method. The linearity and recovery were investigated for known impurities in the range of 0.025 to 1.0%, with respect to the drug concentration in the prepared sample. The linearity of the calibration curve for each of the impurities and torsemide was found to be very good (r2 > 0.999). Relative response factors for each of the known impurities were established by the slope ratio method from the linearity study.

Development and validation of a reversed-phase ultra-performance liquid chromatographic method for assay of lacidipine and related substances.

A simple isocratic, RP-ultra-performance LC method was developed and validated for the determination of lacidipine, three process impurities formed during synthesis, and three degradation products present in drug substance and the drug product. An efficient chromatographic separation was achieved on an Acquity BEH C18 column using pH 4.5 ammonium acetate-acetic acid buffer-methanol (70 + 30, v/v) mobile phase. The monitoring wavelength was 240 nm, and the flow rate 0.25 mL/min. Forced degradation studies using acid, alkali, peroxide, water, heat, and light were conducted, and all impurities were separated. The method was validated successfully for specificity, precision, linearity, accuracy, LOD, LOQ, and robustness, according to International Conference on Harmonization guidelines. The linearity of the calibration curve for lacidipine and each impurity was found to be very good (r2 > 0.999). This method is shown to be suitable for analysis of lacidipine to evaluate the quality of drug substance and a drug product.

Identification and characterization of a principal oxidation impurity in clopidogrel drug substance and drug product.

The focus of this study is identification, isolation and characterization of a principal oxidation impurity of clopidogrel which ranged from 0.05 to 0.12% using high performance liquid chromatography. This impurity is considered as principal oxidation impurity as it is observed in oxidative degradation (stress) study. Preparative HPLC with Xterra MS C18 ODB column was used to isolate the impurity. The isolated impurity was co-injected with the sample containing impurities and found the retention time match of the spiked impurities. A thorough study was undertaken to characterize this impurity and based on their spectral data (UV, MS, MSn 1H/13C, DEPT and 2D NMR) the structure was characterized as 5-[1-(2-chlorophenyl)-2-methoxy-2-oxoethyl]-6,7-dihydrothieno[3,2-c]pyridin-5-ium with a molecular weight 320 amu.