EFFECT OF SODIUM-CHLORIDE ON PHYSICAL CHARACTERISTICS OF POLOXAMER 407 SOLUTIONS

Poloxamer 407 concentrated solutions display an exponential increase in viscosity with temperature. Addition of sodium chloride to these solutions increases the slope of the viscosity vs temperature relationship. In this work the effect of the addition of sodium chloride on the diffusion of atrial natriuretic factor (ANF) in the poloxamer solution and on the C-13 NMR analysis of the solution was studied. Sodium chloride 2% reduced the diffusion coefficient of ANF in 25% poloxamer 407 solution. This reduction was more important at 37°C than at 10°C. As a comparison concentrating poloxamer to 30% also reduced the diffusion coefficient of ANF but showed similar levels of reduction at 37 and 10°C. C-13 NMR analysis showed no interaction between the ions and the polymer. A shift was observed in the oxypropylene spectrum at a given temperature. At higher poloxamer concentration or in the presence of NaCl this transition temperature was decreased. © 1990.