[Concentration influence of some polymers on dermatological hydrogels pH]

For last two decades there is a lot interest in skin pH research, and pH influence on the skin barrier function. A wide range of hydrophilic polymers are applied worldwide for topical and transdermal preparation, influencing acid mantle of the skin. One of the determinants for feasibility of the polymer for dermatological application, and for proper drug release kinetics is the pH. The aim of the work was pH determination of some polyacrylic acid hydrogels and methylcellulose hydrogels in different concentrations. Carbopol 934 pH was 2.473 to 3.682 in concentrations between 0.1% and 2.0%. In the same concentrations carbopol 971 was in the range of 2.923 and 3.862, and carbopol 980 reached the values 2.638-3.763. pH of methylcellulose gels in the range 0.1%-2.0% was 5.136-7.265. Methylcellulose gels were at the higher physiological skin pH rate, and the polyacrylic gels ranged in rather acidic pH. Determined hydrogen ion concentration was a function of polymer concentration, also in the case of nonionic polymer concentration--similar to a logarythmic function. Stable polymer dispersion pH values were reached after determined time, following statistical consideration.