Investigation of cryoprotection on the viability of freeze dried probiotics

Aims: The aim of the present work was to evaluate the effect of various cryoprotective agents on the survival of freezedried probiotic Lactobacillus rhamnosus. Methodology and results: Investigation was done on the viability and stability of probiotics L. rhamnosus. The effect of different cryoprotective agents (namely, sodium chloride, sucrose, dextran, sorbitol, monosodium glutamate, glycerol, skim milk and skim milk with malt extract) with modified De-Man Rogosa Sharpe (MMRS) medium were examined. Commercial De-Man Rogosa Sharpe (MRS) medium was proved to be more expensive than the modified MRS medium with relatively low yield of probiotics L. rhamnosus. Significantly high viable counts were achieved with monosodium glutamate, skim milk and skim milk with malt extract, with optimum concentration at 0.3% w/v. There was a reduction in cell viability at concentration above 0.5% w/v, which could be attributed to cell shrinkage associated with osmotic pressure changes. The cells were found to be stable at room temperature (28 °C) for eight weeks. A significant growth of probiotics was produced from skim milk. Conclusions: Modified MRS medium with skim milk is suggested for the remarkable growth and yield of probiotic lactobacilli.

RP-HPLC analytical method development and optimization for quantification of donepezil hydrochloride in orally disintegrating tablet

An easy, fast and validated RV-HPLC method was invented to quantify donepezil hydrochloride in drug solution and orally disintegrating tablet. The separation was carried out using reversed phase C-18 column [Agilent Eclipse Plus C-18] with UV detection at 268 nm. Method optimization was tested using various composition of organic solvent. The mobile phase comprised of phosphate buffer [0.01M], methanol and acetonitrile [50:30:20, v/v] adjusted to pH 2.7 with phosphoric acid [80%] was found as the optimum mobile phase. The method showed intraday precision and accuracy in the range of 0.24% to -1.83% and -1.83% to 1.99% respectively, while interday precision and accuracy ranged between 1.41% to 1.81% and 0.11% to 1.90% respectively. The standard calibration curve was linear from 0.125 micro g/mL to 16 micro g/mL, with correlation coefficient of 0.9997 +/- 0.00016. The drug solution was stable under room temperature at least for 6 hours. System suitability studies were done. The average plate count was > 2000, tailing factor <1, and capacity factor of 3.30. The retention time was 5.6 min. The HPLC method was used to assay donepezil hydrochloride in tablet and dissolution study of in-house manufactured donepezil orally disintegrating tablet and original Aricept