Characterization of the Rheological, Mucoadhesive, and Drug Release Properties of Highly Structured Gel Platforms for Intravaginal Drug Delivery

This investigation describes the formulation and characterization of rheologically structured vehicles (RSVs) designed for improved drug delivery to the vagina. Interactive, multicomponent, polymeric platforms were manufactured containing hydroxyethylcellulose (HEC, 5 % w/w) polyvinylpyrrolidone (PVP, 4 % w/w), Pluronic (PL, 0 or 10 % w/w), and either polycarbophil (PC, 3 % w/w) or poly(methylvinylether-co-maleic anhydride) (Gantrez S97, 3 % w/w) as a mucoadhesive agent. The rheological (torsional and dynamic), mechanical (com-pressional), and mucoadhesive properties were characterized and shown to be dependent upon the mucoadhesive agent used and the inclusion/exclusion of PL. The dynamic rheological properties of the gel platforms were also assessed following dilution with simulated vaginal fluid (to mimic in vivo dilution). RSVs containing PC were more rheologically structured than comparator formulations containing GAN. This trend was also reflected in formulation hardness, compressibility, consistency, and syringeability. Moreover, formulations containing PL (10% w/w) were more rheologically structured than formulations devoid of PL. Dilution with simulated vaginal fluids significantly decreased rheological structure, although RSVs still retained a highly elastic structure (G ′> G′ ′ and tan δ < 1). Furthermore, RSVs exhibited sustained drug release properties that were shown to be dependent upon their rheological structure. It is considered that these semisolid drug delivery systems may be useful as site-retentive platforms for the sustained delivery of therapeutic agents to the vagina

A potential application of a piezoelectric atomiser for ophthalmic drug delivery

A liquid atomiser composed of a piezoelectric transducer and a metal plate with numerous micro-apertures is studied to identify the most influential factors on its atomising performance. The Taguchi method is employed in the experiment design and analysis of the study on how each factor acts in the atomising process. An optimal condition is determined for producing a stream of droplets. The study shows that the droplet size and the spraying velocity are suitable for ophthalmic drug delivery application, with an even distribution of the drug over most of the eyeball surface area due to the controllable cross-sectional area of the droplet stream. This greatly improves the treatment effectiveness and efficiency of eye therapy. Finally, a structure of the ophthalmic drug delivery system is proposed.<br /

Physicochemical Properties and Dissolution Studies of Dexamethasone Acetate-β-Cyclodextrin Inclusion Complexes Produced by Different Methods

Inclusion complexes between dexamethasone acetate (DMA), a poorly water soluble drug, and β-cyclodextrin (βCD) were obtained to improve the solubility and dissolution rate of this drug. Phase-solubility profile indicated that the solubility of DMA was significantly increased in the presence of βCD (33-fold) and was classified as AL-type, indicating the 1:1 stoichiometric inclusion complexes. Solid complexes prepared by different methods (kneading, coevaporation, freeze drying) and physical mixture were characterized by differential scanning calorimetry, thermogravimetry, infrared absorption and optical microscopy. Preparation methods influenced the physicochemical properties of the products. The dissolution profiles of solid complexes were determined and compared with those DMA alone and their physical mixture, in three different mediums: simulated gastric fluid (pH 1.2), simulated intestinal fluid (pH 7.4) and distilled water. The dissolution studies showed that in all mediums DMA presented an incomplete dissolution even in four hours. In contrast, the complexes formed presented a higher dissolution rate in simulated gastric fluid (SGF pH 1.2), which indicate that these have different ionization characteristics. According to the results, the freeze–dried and kneaded products exhibited higher dissolution rates than the drug alone, in all the mediums