Cytotoxicity and immunogenicity evaluation of synthetic cell-penetrating peptides for methotrexate delivery

Methotrexate (MTX) is one of the most effective therapeutics to treat different types of solid tumors; however, it suffers low permeability limiting its bioavailability and cellular uptake. To tackle this, we aim to design and fabricate different types of cell-penetrating peptides (CPPs) to improve the intracellular uptake of MTX without causing any immunogenic response. CPPs were synthesized by the solid-phase peptide synthesis method. Peptide-MTX conjugates were prepared via covalent binding of peptide and drug molecule. CPPs and peptide-E8 nanoparticles were characterized using zeta-sizer and scanning electron microscopy. Cytotoxicity of CPPs and peptide-MTX conjugates was evaluated by MTT assay. An enzyme-linked immunosorbent assay was employed to assess the IL-6 and TNF-α cytokine release profile. Amongst all sequences, W4 R4-MTX possessed the highest loading efficiency (97%) and drug to peptide percentage (24.02%). The lowest loading efficiency (36%) and drug to peptide percentage (8.76%) were seen for NGRWK-MTX conjugates. The NGRWR peptide and NGRWR-E8 nanoparticles had acceptable size (~100 nm) with spherical and rod-like structures, respectively. The selected CPPs and peptide-MTX conjugates did not show any cytotoxicity or immunogenicity. The fabricated peptides are represented as promising carriers to improve the intracellular delivery of MTX to cancer cells with low immunogenic and cytotoxic effects on normal cells

Compatibility studies of acyclovir and lactose in physical mixtures and commercial tablets

This study documents drug-excipient incompatibility studies of acyclovir in physical mixtures with lactose and in different tablet brands. Differential scanning calorimetry (DSC) was initially used to assess compatibility of mixtures. The Fourier-transform infrared (FTIR) spectrum was also compared with the spectra of pure drug and excipient. Although DSC results indicated incompatibility with lactose, FTIR spectra were mostly unmodified due to overlapping peaks. Samples of isothermally stressed physical mixture were stored at 95 degrees C for 24 h. The residual drug was monitored using a validated high-performance liquid chromatography (HPLC) assay and data fitting to solid-state kinetic models was performed. The drug loss kinetics followed a diffusion model. The aqueous mixture of drug and excipient was heated in order to prepare an adduct mixture. HPLC analysis revealed one extra peak that was fractionated and subsequently injected into the liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) system. The MRM (Multiple Reaction Monitoring) chromatograms characterized the peak with molecular mass corresponding to an acyclovir-lactose Maillard reaction product. The presence of lactose in commercial tablets was checked using a new TLC method. Overall, the incompatibility of acyclovir with lactose was successfully evaluated using a combinadon of thermal methods and LC-MS/MS. I (C) 2009 Published by Elsevier B.V

Detection of gabapentin-lactose Maillard reaction product (Schiff's Base): Application to solid dosage form preformulation. Part 1

In the following study several techniques are utilized such as Differential Scanning Calorimetery (DSC), Infra-Red (IR) spectroscopy, High Performance Liquid Chromatography (HPLC) and Liquid Chromatography-Mass Spectrometry/Mass Spectrometry (LC-MS/MS) to characterize gabapentin (GBP) and lactose incompatibility in solid state binary mixtures and also in different capsule brands. Solid and aqueous mixtures of the drug and excipient were heated in order to prepare the adduct mixture. Based on the DSC results incompatibility was demonstrated and the imine formation was subsequently evaluated using FTIR spectra. HPLC analysis revealed two extra peaks (compound 1G and 2G) that were fractionated and then injected into LC-MS/MS system. Mass spectra of compound 2G was successfully correlated to GBP-lactose Maillard reaction product. The MRM (Multiple Reaction Monitoring) achieved using a new internal standard and was capable of detecting 4 separate peaks. The LC-MS/MS method was validated and then used for quantifying the amount of remaining drug in the test samples. The presence of lactose in commercial capsules was checked using a TLC method. Overall, the incompatibility of GBP with lactose was successfully evaluated using a combination of thermal methods, FTIR, HPLC and LC-MS/MS

Assessment of Feasibility of Maillard Reaction between Baclofen and Lactose by Liquid Chromatography and Tandem Mass Spectrometry, Application to Pre Formulation Studies

The aim of this study was to determine any possible, baclofen–lactose Maillard reaction products. Granules and tablets of baclofen and lactose were prepared and maintained in heat ovens for a certain time period. The effects of lactose type, addition of magnesium stearate, and water were monitored. Heated lactose and baclofen were analyzed using reverse-phase HPLC. Liquid chromatography tandem mass spectroscopy revealed nominal mass values consistent with baclofen–lactose, early-stage Maillard reaction condensation products (ESMRP). Multiple reaction monitoring confirmed the presence of ESMRP as well. FTIR analysis proved the formation of imine bond. The results indicated that baclofen undergoes a Maillard-type reaction with lactose