Preparation and characterization of methacrylate hydrogels for zeta potential control

A technique based on the measurement of streaming potentials has been developed to evaluate the effects of hydrophilic coatings on electroosmotic flow. The apparatus and procedure are described as well as some results concerning the electrokinetic potential of glass capillaries as a function of ionic strength, pH, and temperature. The effect that turbulence and entrance flow conditions have on accurate streaming potential measurements is discussed. Various silane adhesion promoters exhibited only a slight decrease in streaming potential. A coating utilizing a glycidoxy silane base upon which methylcellulose is applied affords a six-fold decrease over uncoated tubes. Hydrophilic methacrylate gels show similar streaming potential behavior, independent of the water content of the gel. By introduction of positive or negative groups into the hydrophilic methacrylate gels, a range of streaming potential values are obtained having absolute positive or negative signs

BIODEGRADABLE CONTRACEPTIVE DRUG DELIVERY SYSTEM.

Sustained release of drugs from polymeric matrices has received increased interest. However, unitl now only a few examples are available where steroids are covalently bonded to a polymeric system and no data are available about the coupling of steroids to biodegradable polymers. This paper reports a new derivatization of 17 alpha -ethynyl-17 beta -hydroxy steroids, which is applicable for attachment to biodegradable poly( alpha -amino acids). Poly(hydroxyalkyl)-L-glutamines are prepared through base catalyzed polymerization of gamma -benzyl-L-glutamate N-carboxyanhydride giving the polymeric benzyl-L-glutamate, followed by displacement of the benzyl group with the desired hydroxyalkyl amines. The polymers are water soluble but upon substitution with hydrophobic steroids become water insoluble. Microparticles of the drug-polymer conjugate have been subcutaneously implanted in female rats. Liquid scintillation counting of urine and feces indicate that the contraceptive steroid is released in near zero order kinetics for more than 200 days