Optimization of a formulation containing viable lactic acid bacteria

In the present study, gastric juice resistant tablet formulations of lactic acid bacteria (LAB) were developed, using hydroxypropylmethylcellulose acetate succinate (HPMCAS) as well as alginates, apple pectin and Metolose ® as matrix forming components. To optimize the formulation—using survival rate in acid medium, and disintegration time in intestinal fluid as test parameters—tablets were modified with respect to LAB content, amount of applied excipients per tablet, and compaction forces. A decrease of viable cells of not more than one log unit after 2 h of incubation in acid medium was desired, as well as a disintegration time of 1 h in phosphate buffer pH 6.8. It was found that the amount of HPMCAS in the tablet correlates with gastric juice resistance. As HPMCAS also leads to a decrease of disintegration time in intestinal fluid, slight amounts of this excipient were preferred. The best protective qualities against artificial gastric juice were observed when tablets were prepared from compaction mixtures of LAB, HPMCAS and sodium alginate.