Simona Ardelean

Thermal behaviour of procaine and benzocaine Part II: compatibility study with some pharmaceutical excipients used in solid dosage forms

BackgroundThe compatibility study of active substances with excipients finds an important role in the domain of pharmaceutical research, being known the fact that final formulation is the one administered to the patient. In order to evaluate the compatibility between active substance and excipients, different analytical techniques can be used, based on their accuracy, reproducibility and fastness.ResultsCompatibility study of two well-known active substances, procaine and benzocaine, with four commonly used excipients, was carried out employing thermal analysis (TG/DTG/HF) and Fourier Transform Infrared Spectroscopy (UATR-FT-IR). The selected excipients were microcrystalline cellulose, lactose monohydrate, magnesium stearate and talc. Equal proportion of active substance and excipients (w/w) was utilized in the interaction study. The absolute value of the difference between the melting point peak of active substances and the one corresponding for the active substances in the analysed mixture, as well the absolute value of the difference between the enthalpy of the pure active ingredient melting peak and that of its melting peak in the different analysed mixtures were chosen as indexes of the drug-excipient interaction degree. All the results obtained through thermal analysis were also sustained by FT-IR spectroscopy.ConclusionsThe corroboration of data obtained by thermal analysis with the ones from FT-IR spectroscopy indicated that no interaction occurs between procaine and benzocaine, with microcrystalline cellulose and talc, as well for the benzocaine-lactose mixture. Interactions were confirmed between procaine and benzocaine respectively and magnesium stearate, and for procaine and lactose.

Influence of emulsifiers on the characteristics of polyurethane structures used as drug carrier

BackgroundEmulsifiers have a significant role in the emulsion polymerization by reducing the interfacial tension thus increasing the stability of colloidal dispersions of polymer nanostructures. This study evaluates the impact of four emulsifiers on the characteristics of polyurethane hollow structures used as drug delivery system.ResultsPolyurethane (PU) structures with high stability and sizes ranging from nano- to micro-scale were obtained by interfacial polyaddition combined with spontaneous emulsification. The pH of PU aqueous solutions (0.1% w/w) was slightly acidic, which is acceptable for products intended to be used on human skin. Agglomerated structures with irregular shapes were observed by scanning electron microscopy. The synthesized structures have melting points between 245-265°C and reveal promising results in different evaluations (TEWL, mexametry) on murine skin.ConclusionsIn this study hollow PU structures of reduced noxiousness were synthesized, their size and stability being influenced by emulsifiers. Such structures could be used in the pharmaceutical field as future drug delivery systems.

Mistletoe and Garlic Extracts as Polyurethane Carriers – A Possible Remedy for Choroidal Melanoma

BACKGROUND Melanoma is known as the most dangerous form of skin cancer; whereas the malignant choroidal melanoma is an orphan disease known as the most common primary intraocular malignancy in adults. Literature suggests that the consumption of garlic and mistletoe leads to a reduced risk of developing cancer. OBJECTIVE The aim of this study was the obtaining and the characterization of polymer structures containing mistletoe or garlic extract. METHODS The structures were obtained in a polyaddition process combined with a spontaneous emulsification; they were characterized by pH, size, Zeta potential and DSC measurements, evaluation of encapsulation efficacy, penetrability through membranes and in vitro cytotoxicity tests. RESULTS The microstructures present sizes between 1.05 and 2.60 µm and Zeta potentials between -7 and +36 mV. A good encapsulation was observed on different evaluations (88-92%). It was determined that approx. 30% of polymer microstructures containing vegetal extracts pass through an artificial membrane in 4 days. An in vitro cytotoxicity test revealed that these products are safe for administration. The analysis of antitumor efficacy indicates that garlic extracts have important effects after 48 and 72 hours on A375 cells; however, polymer microstructures with herbal extracts did not reveal antiproliferative activities on A375 cells because these polymer structures present a slow degradation. CONCLUSION Sterile eye drops solutions based on polymer microstructures containing garlic or mistletoe extracts were obtained; the sample based on garlic extracts may be used in the pharmaceutical field as drug carrier with an antiproliferative effect which occurs after a prolong period.