A Calorimetric Study on Diflunisal Release from Poly(Lactide-co-Glycolide) Microspheres by Monitoring the Drug Effect on Dipalmitoylphosphatidylcholine Liposomes: Temperature and Drug Loading Influence

Diflunisal release from poly-Lactide-co-Glycolide (50:50, 34,000 MW) microspheres loaded with two different amounts of drug (2.5 +/- 0.5% and 10 +/- 0.5% w/w) was monitored by following the effects exerted by the drug on the thermotropic behavior of dipalmitoylphosphatidylcholine unilamellar vesicles at different temperatures. The effects of the drug released from the microspheres on the thermotropic behavior of lipid aqueous dispersion containing different molar ratios of drug was detected by differential scanning calorimetry and was compared with the effects exerted by the free Diflunisal. Diflunisal affects mainly the temperature (Tm) of the transition characteristic of phospholipid vesicles as model biomembrane, causing a shift toward lower values. This shift was modulated by the drug molar fraction with respect to the lipid concentration in the aqueous dispersion. Afterward, calorimetric measurements were performed on suspensions of blank liposomes added to weighed amounts of unloaded and differently Diflunisal-loaded microspheres as well as free powdered Diflunisal after incubation for increasing times at three different temperatures (25, 37, and 50 degrees C). The Tm shifts of the lipid bilayer, caused by the drug released from polymeric system as well as by the free drug during incubation periods, were compared with that caused by free drug increasing molar fractions dispersed directly on the membrane, employed as a calibration curve to obtain the fraction of drug released. This in vitro study suggests that the kinetic process involved in drug release is influenced by the amount of drug loaded in the microspheres as well as by the temperature acting on drug solubility and membrane disorder. This drug release model, monitored by the calorimetric technique shows that a) the poly-Lactide-co-Glycolide microspheres are a good delivery system able to sustain the drug release; b) the differential scanning calorimetry technique applied on the drug interaction with biomembranes constitutes a good tool to follow the drug release; 3) this model, representing an innovative alternative in vitro model, should be used to determine the different kinetics involved in the drug transfer from a drug delivery system to a membrane as uptake site

Indomethacin-Dipalmitoylphosphatidylcholine Interaction. A Calorimetric Study of Drug Release from Poly(Lactide-co-glycolide) Microspheres into Multilamellar Vesicles.

A comparative study of indomethacin controlled release from poly(lactide-co-glycolide) (50:50, molecular weight 3000) (PLGA) microspheres loaded with two different amounts of drug (10.9 ± 1%, and 34.1 ± 1% w/w) and pure free indomethacin, considering the effects exerted by the drug on the thermotropic behavior of dipalmitoylphosphatidylcholine multilamellar vesicles, was carried out by differential scanning calorimetry (DSC). The release was monitored by comparing the effect exerted by the free indomethacin on lipid thermotropic behavior with that of the drug released by the microspheres and relating these effects to a lipid aqueous dispersion containing the molar ratio of drug able to cause it. By DSC measurements, the pure free indomethacin was found to be able to have a fluidifying effect on the model membrane, causing a shift toward lower values of the transitional temperature (Tm), characteristic of phospholipid liposomes, without variations in the enthalpic changes (ΔH). This shift was found to be modulated by the drug molar fraction with respect to the lipid concentration in the aqueous dispersion. Successively, calorimetric measurements were performed on suspensions of blank liposomes added to weighed amounts of unloaded and indometha-cin-loaded microspheres as well as free powdered indomethacin, and the Tm shifts of the lipid bilayer caused by the drug released from the polymeric system, as well as by the free drug, were compared with that caused by free drug increasing molar fractions dispersed directly on the membrane, employed as a calibration curve to obtain the fraction of drug released. This drug release model could be employed to determine the different kinetics involved in the drug transfer from the microspheres to a membrane. This in vitro study suggests that the kinetic process involved in drug release is influenced by the amount of drug loaded in the microspheres. This calorimetric study shows that the PLGA microspheres are a good delivery system able to sustain drug release. Moreover, the DSC technique applied to the drug interaction with biomembranes constitutes a good tool for determining the drug release representing an innovative alternative in vitro model

Transient transfection of porcine granulosa cells after 3D culture in barium alginate capsules

Three-dimensional culture systems in barium alginate capsules can be employed to maintain primary granulosa cells in an undifferentiated state for almost 6 days. This is due to a self-organization of cells in a pseudofollicular structure. The transfection of primary granulosa cells is a necessary condition when employing these culture systems for several purposes, for example as an in vitro toxicity test or the development of oocytes or zygotes. In this work, the feasibility of two transient transfection techniques (liposome-mediated and electroporation) was assessed in primary porcine granulosa cells after a 6-day culture in an artificial extracellular matrix (barium alginate membrane). Human recombinant green fluorescent protein was chosen as a molecular readout, and protein expression was assessed after 48 hours from transfection. Liposome-mediated transfection gave low transfection levels, with increasing yields from 2 to 12 microgDNA/ml of medium; the maximum percentage (85.7%) was reached at 12 microgDNA/ml of medium. Electroporation-mediated transfection yields were higher: the best results (81.7% of transfected cells) were achieved with two 50V pulses and 12 microg/ml DNA. The application of a single or double pulse (50V) at 4 mgDNA/ml gave negligible results. These results indicate that primary granulosa cell cultured in barium alginate capsules can be transfected by electroporation with high transfection yields

Therapeutic system for the controlled release of active ingredients

A system designed to release one or more active substances in different, previously programmable modes, is described. The system is constituted by a tablet in three layers, two of which (the outer layers) vehicularise the active ingredient(s), whilst the third (the central layer) is constituted of a polymeric barrier which does not contain active substance and has the appropriate characteristics of erodibility or gelation. The tablet is completely coated with a film of polymeric material insoluble in water and/or in aqueous fluids, on which one or more incisions delimiting an area of exactly calculated geometric shape and size, have been made through the use of a laser beam of appropriate power and intensity. The removal of the film inside the incision(s) allows the release of the active ingredient(s) into aqueous fluid in predetermined amounts and umes. The procedure for the production of the aforementioned pharmaceutical form is also described

Pharmaceutical tablet suitable to deliver the active substance in subsequent and predeterminable times

Pharmaceutical tablet, capable of delivering the active substance or the active substances, according to a predeterminable release profile, comprising a core with an external partial coating in which said core consists of 3 layers, wherein the upper layer contains an amount of the active substance with suitable excipients, the intermediate layer consists of polymeric material with retarding barrier function and the lower layer contains the remaining amount of the active substance with suitable excipients and said external coating consists of controlled permeability polymeric materials, applied by compression to the lower surface and to the lateral surface of the core

Forme farmaceutiche antivirali per applicazione vaginale

Biocompatible sustained-release vaginal antiviral compositions in form of effervescent tablets, bioadhesive tablets, bi-layered tablets, bioadhesive washes, are described