ABSTRACT
Colloidal cubic phase particles formed in the monoolein/poloxamer/water system are being investigated as potential drug carriers for, e.g., intravenous administration. Preparation methods must, however, still be further developed to reliably yield monoolein dispersions with cubic particles in a size range acceptable for i.v. administration and adequate long-term stability. In this context, the influence of different composition and preparation parameters on the properties of monoolein dispersions prepared by high-pressure homogenization was studied. High pressure homogenization of coarse poloxamer 407-stabilized monoolein/water mixtures leads to dispersions with a large fraction of micrometer-sized particles at low poloxamer concentrations. Higher poloxamer concentrations lead to lower mean particle sizes but the fraction of cubic particles becomes smaller and vesicular particles are observed instead. A study of the characteristics of a dispersion with a standard composition indicated that the homogenization temperature has a much stronger influence on the dispersion properties than the homogenization pressure or the type of homogenizer used. Temperatures around 40-60 degrees C lead to the most favorable dispersion properties. The high temperature sensitivity of the preparation process appears to be at least partly correlated with the phase behavior of the dispersed particles determined by temperature-dependent X-ray diffraction.
Subject(s)
Glycerides , Water , Emulsions , Glycerides/chemistry , Nanoparticles , Phase Transition , Poloxamer , Water/chemistry , X-Ray DiffractionABSTRACT
After a synopsis of brain stem structures participating in swallowing, the main neurologic diseases are presented as a part of which swallowing disorders may occur: central and peripheral nervous system, motor end-plates and muscles can be involved. The sequence of clinical examination is described with special reference to findings in mouth, pharynx and larynx as well as to findings in high-frequency cinematography. After description of normal swallowing pre-, intra- and postdeglutitive mechanisms of aspiration are shown. This distinction has proved useful for practical reasons. Finally we give a survey of therapeutic possibilities reported in recent years in literature and developed in our hospital, divided into indirect (facilitation of orofacial and laryngeal voluntary muscles) and direct therapeutic strategies (strategy of compensation during feeding). In connection with this therapeutic possibilities applied during pre-, intra- and postdeglutitive phase, depending on neuromuscular disturbances, are also described.
