Development and Validation of a Stability Indicating RP-HPLC Method for Hydrocortisone Acetate Active Ingredient, Propyl Parahydroxybenzoate and Methyl Parahydroxybenzoate Preservatives, Butylhydroxyanisole Antioxidant, and Their Degradation Products in a Rectal Gel Formulation.

A stability indicating method was established through a stress study, wherein different methods of degradation (oxidation, hydrolysis, photolysis, and temperature) were studied simultaneously to determine the active ingredient hydrocortisone acetate, preservatives propyl parahydroxybenzoate, and methyl parahydroxybenzoate, antioxidant butylhydroxyanisole (BHA), and their degradation products in a semisolid dosage gel form. The proposed method was suitably validated using a Zorbax SB-Phenyl column and gradient elution. The mobile phase consisted of a mixture of methanol, acetonitrile, and water in different proportions according to a planned program at a flow rate of 1.5 mL/min. The diode array detector was set at 240 nm for the active substance and two preservatives, and 290 nm for BHA. The validation study was conducted according to International Conference on Harmonization guidelines for specificity, linearity, repeatability, precision, and accuracy. The method was used for QC of hydrocortisone acetate gel and for the stability studies with the aim of quantifying the active substance, preservatives, antioxidant, and degradation products. It has proved to be suitable as a fast and reliable method for QC.

Chitosan nanoparticles as non-viral gene delivery systems: determination of loading efficiency.

Chitosan has been studied for use in particle delivery systems for therapeutic purposes, since one of its most important applications is as a non-viral vector in gene therapy. Due to its positive charge, it is capable of forming DNA complexes (polyplexes) obtained through several methods and with the property of protecting nucleic acids. Two methods for obtaining the nanoparticles of chitosan-nucleic acids are reported in this study: simple complexation (of depolymerized chitosan or of different chitosan salts with plasmid) and ionic gelation (by adsorption of plasmid in the nanoparticles or by encapsulation of plasmid into nanoparticles). The determination of the loading efficiency of chitosan nanoparticles with the plasmid is carried out by electrophoretic mobility of the samples on agarose gel. Furthermore, the nanoparticles have been characterized according to their morphology, size and surface charge using AFM, TEM, laser diffraction and dynamic light scattering techniques. The polyplexes obtained have been found to be spherical and nanometric in size (between 100-230nm) with a zeta potential between 37 and 48mV. Positive results have been obtained by agarose gel electrophoresis for all studied cases: a concentration of between 20 and 30µg/mL of chitosan salts is required while for the remaining chitosan samples studied, 100% loading efficiency does not occur until a concentration equal to 100µg/mL (regardless of previous depolymerisation and the method performed). Chitosan-plasmid nanocapsules have been obtained at the polymer concentrations worked with (between 0.025 and 0.2%).