Showing papers by "Nicholas A. Peppas published in 1981"
TL;DR: In this article, drug release mechanisms from, and diffusion processes in hydrophilic crosslinked polymeric systems were investigated in two macromolecular states: in the glassy and rubbery states during the early part of countercurrent water diffusion, and in the rubbery state after thermodynamic equilibrium between the network and the surrounding dissolution medium (water) was attained.
399 citations
TL;DR: A new dosage form designed to provide parenteral drug delivery over a prolonged period of time following a standard injection using testosterone as the model drug consists of a biodegradable, biocompatible polymer in which the drug is dispersed on a molecular level.
Abstract: A new dosage form designed to provide parenteral drug delivery over a prolonged period of time following a standard injection has been investigated using testosterone as the model drug. The drug carrier consists of a biodegradable, biocompatible polymer in which the drug is dispersed on a molecular level. The polymer itself is formulated as a pseudolatex with high solid content (40.0%). The formulation has a low viscosity (97 cps) which can be injected easily through a hypodermic needle. The histopathology study showed good tissue compatibility of the pseudolatices and in-vivo tests on rats confirmed a prolonged release of drug over a 14 day period. The stability of the biodegradable poly-d, l-lactic acid latex was found not to be significantly changed over 120 days of storage at room temperature (25°). A six month study showed a slight increase (10%) in the viscosity of the parenteral product when stored at room temperature. The increase was attributed to partial coalescence of the polymer partic...
178 citations
TL;DR: In this article, the authors measured the oxygen permeability of polymeric materials used for hard and soft contact lens applications using a gas-to-water oxygen permeation technique, where the oxygen is dissolved and measured with an oxygen analyzer.
82 citations
Journal Article•
19 citations
TL;DR: In this article, a new method of crosslinking of polystyrene using difunctional chloromethylated cross-linking agents is reported, which took place in dichloroethane with SnCl4 as a catalyst at 80°C and with molar ratios of poly styrene to crosslink agent ranging from 1∶2 to 12∶1.
Abstract: A new method of crosslinking of polystyrene using difunctional chloromethylated crosslinking agents is reported. The solution crosslinking took place in dichloroethane with SnCl4 as a catalyst at 80°C and with molar ratios of polystyrene to crosslinking agent ranging from 1∶2 to 12∶1. The crosslinked networks prepared by this method had thermal transitions considerably affected by the degree of crosslinking. Ion-exchange resins were prepared by sulfonation of these networks. Water swelling ratios as high as 16.2 were measured leading to indications about the physical structure of these networks.
14 citations
26 Oct 1981
11 citations