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Biomedical subjects

R G Linford

Publications and source records attributed to R G Linford.

4 recordsLinked to original sources
PubMed2000

In vitro iontophoretic release of lithium chloride and lidocaine hydrochloride from polymer electrolytes.

Ionically conducting polymers, frequently known as polymer electrolytes, are potential candidates as hosts for drugs to be delivered iontophoretically. The iontophoretic delivery of lithium or lidocaine from polymer electrolyte films through a cellophane membrane was examined using different delivery current regimes. Thin, mechanically strong, polymer electrolyte films were fabricated from poly(ethylene oxide) (PEO) with lithium chloride or lidocaine hydrochloride. Experiments showed that iontophoretic transport of both lithium chloride and lidocaine hydrochloride might be achieved from these PEO-based films. Cation transport number determinations give values for PEO-based films of about 0.4 for lithium chloride systems and 0.12 for lidocaine hydrochloride systems. The mechanism of transport from these PEO-based polymer electrolyte films allows the delivery of ionic salts such as lithium chloride and lidocaine hydrochloride to be controlled solely by current, thus providing a system that can deliver precise amounts of drug.

Anesthetics, Local↗
PubMed1999

Physical characterization of polymer electrolytes as novel iontophoretic drug delivery devices.

Polymer electrolytes are solid-like materials formed by dispersing a salt at the molecular level in a high molecular weight polymer such as poly(ethylene oxide) (PEO). They have been extensively studied for use in electrochemical applications such as batteries and display devices. This paper considers a novel application of polymer electrolytes as the basis of iontophoretic drug delivery systems. Polymer electrolyte films were cast from solutions of PEO and various drug salts using either water or an acetonitrile/ethanol mixture as the solvent. These films were characterized by variable-temperature polarizing microscopy (VTPM), differential scanning calorimetry (DSC), and alternating current (AC) impedance analysis. The films were around 100-micron thick and mechanically strong; the optical and thermal methods provided evidence that the polymer electrolytes had crystalline and amorphous phases, although some drugs may exist in films as nanodispersions. The amorphous phase is important as ions have greater mobility in this phase and therefore allow a current to be passed when the material is incorporated into a device such as one suitable for drug delivery by iontophoresis. The AC impedance analysis showed that the conductivity of the films varied between 10(-6) and 10(-3) S cm-1, depending on the salt, casting solvent, and temperature. Two drugs in particular were shown to be promising candidates in these systems: lidocaine hydrochloride and lithium chloride.

Drug Delivery Systems↗