Liquid Crystalline Polymer Pouches for Local Anaesthetic Emulsion

In order to enhance the long-term properties of a high-pH local anaesthetic drug, emulsion tests were conducted where the emulsion was stored in pouch es made of a compression moulded high-barrier liquid-crystalline polymer, V ectra A950. The oxygen permeability of the pouch materia I was too low to b e detected at 23 degreesC and 0% relative humidity with the instrument used . The water vapour transmission rate was 0.135 (g.mm/m(2).day) at 38 degree sC and 100% relative humidity. The emulsion, containing prilocain and lidoc ain as active substances, was stored in pouches which were sealed by the th ermal impulse technique at 260 degreesC for 1.08 s. It was possible to obta in good quality films and good quality seals by optimization of the compres sion moulding and sealing operations. The concentrations of prilocain and l idocain in the emulsion were studied for 14 weeks at two different temperat ures, 40 degreesC and 60 degreesC, and at 100% relative humidity. The decre ase in concentration was higher for prilocain (5.4-8.3%) than for lidocain (3.4-3.6%). The loss of the substances from the emulsion was due mainly to adsorption onto the polar surface of the liquid crystalline polymer. Copyri ght (C) 2001 John Wiley & Sons, Ltd.