THE EFFECT OF SUCROSE LAURATE AND PROPYL 4-HYDROXYBENZOATE COMBINATIONS ON MICROBIAL-GROWTH .2. EVALUATION OF GROWTH OF ESCHERICHIA-COLI AND STAPHYLOCOCCUS-AUREUS IN 2 LIQUID ORAL PHARMACEUTICAL FORMULATIONS

The antimicrobial efficacy of sucrose laurate (SL), propyl 4-hydroxybe nzoate (PPHB) and their combinations was evaluated in two frequently u sed oral liquid preparations. The results of the growth experiments sh owed that 0.020% PPHB and the micellar solution of 2.86% SL and 0.020% PPHB were equally effective in preserving Sirupus simplex (FNA) (1) a nd Mixtura lidocaini 2% (FNA) (2) against all kinds of microbial growt h. An inactivation of the PPHB by SL, which was found in earlier Trypt icase Soya Broth (TSB) growth experiments (3), could not be confirmed. Both the PPHB and the SL/PPHB combination met the requirements of the United States Pharmacopeia (USP XXII), the British Pharmacopoeia (BP 1988) and the Deutsches Arzneibuch (DAB 9). Growth experiments however confirmed previous findings that SL when used alone exhibits some ant imicrobial properties. The results showed that both oral liquid prepar ations could only be partly preserved against bacteria, yeasts or moul ds by 2.86% SL. SL was found to be ineffective against Staphylococcus aureus, Pseudomonas aeruginosa, Saccharomyces cerevisiae and Saccharom yces species. The solid or liquid SL/PPHB combination was shown to ove rcome the slow dissolution rate of the parabens, could easily be store d and additionally, could be simply admixed to the liquid oral prepara tions. Combining these advantages with a high antimicrobial activity, the (solid) micellar solution can offer a new and powerful tool in pre servation techniques.