In vitro dissolution/release methods for mucosal delivery systems

In vitro dissolution/release tests are an indispensable tool in the drug product development, its quality control and the regulatory approval process. Mucosal drug delivery systems are designed to provide both local and systemic drug action following ocular, nasal, oromucosal, vaginal or rectal administration. They exhibit significant differences in formulation design, physicochemical characteristics and drug release properties. Therefore it is not possible to devise a single method which would be suitable for release testing of such versatile and complex dosage forms. Different apparatuses and techniques for in vitro release testing for mucosal delivery systems considering the specific conditions at the administration site are described. In general, compendial apparatuses and methods should be used as a first approach in method development when applicable. However, to assure adequate simulation of conditions in vivo, novel biorelevant in vitro dissolution/release methods should be developed. Equipment set up, the selection of dissolution media and volume, membrane type, agitation speed, temperature, and assay analysis technique need to be carefully defined based on mucosal drug delivery system characteristics. All those parameters depend on the delivery system and physiological conditions at the site of application and may vary in a wide range, which will be discussed in details

In vitro dissolution/release methods for mucosal delivery systems

In vitro dissolution/release tests are an indispensable tool in the drug product development, its quality control and the regulatory approval process. Mucosal drug delivery systems are designed to provide both local and systemic drug action following ocular, nasal, oromucosal, vaginal or rectal administration. They exhibit significant differences in formulation design, physicochemical characteristics and drug release properties. Therefore it is not possible to devise a single method which would be suitable for release testing of such versatile and complex dosage forms. Different apparatuses and techniques for in vitro release testing for mucosal delivery systems considering the specific conditions at the administration site are described. In general, compendial apparatuses and methods should be used as a first approach in method development when applicable. However, to assure adequate simulation of conditions in vivo, novel biorelevant in vitro dissolution/release methods should be developed. Equipment set up, the selection of dissolution media and volume, membrane type, agitation speed, temperature, and assay analysis technique need to be carefully defined based on mucosal drug delivery system characteristics. All those parameters depend on the delivery system and physiological conditions at the site of application and may vary in a wide range, which will be discussed in details

Termoanalitičke metode u farmaciji

Thermal Analysis (TA) is the term used to describe the analytical techniques that measure the physical and chemical properties of a sample as a function of temperature or time. Thermoanalytical methods: DSC, TGA, TOA, TMA and their application in the field of pharmaceutical analysis are reviewed. Due to the different information delivered, they are concurrent or complementary to the other analytical techniques for identification, purity and quantitative determination of the substances. They are unique methods in the field of polymer analysis and of high value for solid state analysis. They are applicable in all fields of pharmaceutical qualitative and quantitative analysis: raw materials, precursors, intermediates, drug substances and excipients, in process control and also in dosage forms. Connection to the robotic system considerably increases the advantages of these methods for routine quality control

Metalloporphyrins. The nature of ligand bonding and the mechanism of replacements

The imidazole ring is an essential component of many biological systems (hemoglobin and myoglobin, nucleic acids, vitamin B^, cytochromes, metalloenzymes, etc.). The nature of the bond between imidazole-nitrogen and the metal is therefore of biological interest. Imidazole is an electron-donating ligand in both a and n sense, much more electron donating than the majority of nitrogen heterocycles. As ligands, most imidazoles are good a donors and moderate n donors. They can also function as n acceptors if the imidazole ring has one or more electron-withdrawing substituents. Our recent study of bonding modes of pyridine and imidazole type ligands in the transition state of a Conl(protoporphyrin IX) model complex enabled us to conclude that stabilization of the reaction transition state is more sensitive to the change in the strength of n bonding than in that of a bonding. This observation is important for some metallo-enzymatic reactions. Mechanisms of replacements in porphyrin and in corrin rings are discussed

Istraživanje eutektičkog sustava acetanilida i fenacetina

The determinations of purity and the phase diagram of eutectic system with acetanilide and phenacetine have been tested by the classic methods and by DSC-method. The eutectic composition at Ten is 65 mole% acetanilide and 35 mole% phenacetine

Normizacija kalijskog bromida za Hrvatsku farmakopeju

Six various samples of potassium bromide are,,investigated as potential reference substances in IR-spectrometry for Croatian pharmacopoeia: KBr for IR-spectrometry, Merck (1); KBr for IR-spectrometry, Fluka (2); KBr purris p.a. ACS, Fluka (3); KBr purum p.a. Ph. Eur., Fluka (4); KBr, WEB (5) and KBr, Zorka Šabac (6). Critical attributive and meiisurement characteristics are established for the field of high-accuracy IR-spectrometry. Selection criteria of a material as standard reference material and steps for certification are described. On the basis of general properties, a certain number of candidate materials is selected as suitable to fulfill the required need. Measurement characteristics of all determinated samples show that samples 1-3 are suitable as substances for making standard of potassium bromide for IR-spectrometry pharmacopoeia measurements

Development of fiber optic in vitro release testing method for dexamethasone release from the oil solutions

For many parenteral drugs, there is still no standardized method for in vitro release (IVR) testing available. This article presents the development of a new IVR method for oil solutions using a dialysis membrane and USP II apparatus coupled to a fiber optic UV-Vis spectrometer. Experiments were performed using dexamethasone formulations containing castor oil as a solvent with the addition of cosolvents, 20 % (v/v) of isopropanol or Capryol® 90. Based on solubility testing results, castor oil was chosen as the best solvent amongst other vegetable oils, while a significant increase in solubility was obtained by adding either of the two cosolvents. Partitioning experiments were performed to ensure these formulations could achieve prolonged drug release. IVR testing was performed with model formulations and critical test parameters were varied in order to examine the method’s sensitivity. The developed method was sensitive to temperature and stirring rate, while coupling the USP II apparatus with a fiber optic UV-Vis spectrometer enabled complete automation. Moreover, due to the interference of excipients on fiber optic detection of dexamethasone during the release testing, derivative spectroscopy was successfully introduced for the elimination of the interference. The developed IVR method described herein could be useful in preformulation investigations and the early development of novel formulations

Evaluation of stability and in vitro wound healing potential of melatonin loaded (lipid enriched) chitosan based microspheres

The aim of this study was to evaluate long-term stability and assess the wound healing potential of the innovative melatonin-loaded lipid-enriched hybrid system compared to conventional melatonin-loaded chitosan microspheres. The hybrid system contained nanostructured lipid carrier incorporated in the chitosan matrix, in order to modify melatonin release and alter physicochemical characteristics of the delivery system. Stability testing was performed during a six-month period under two conditions - refrigerated (5±3 °C) and at room temperature (25 ± 2 °C/60 ± 5 % RH). Samples stored at both conditions were analyzed in terms of particle size, zeta potential, moisture content and thermal properties. At the end of testing, drug content was determined in all samples. Dressings wound healing potential was assessed by in vitro scratch test using human skin fibroblast cell line. Although both systems showed good stability characteristics, the addition of lipids in the system has improved its wound healing potential