Vitamins in Pharmaceutical Formulations

Anti-diabetic activity and stability study of the formulated leaf extract of Zizyphus spina-christi (L.) Willd with the influence of seasonal variation.

Freeze-dried mouse spermatozoa are capable of participating in normal embryonic development after injection into oocytes. When the freeze-dried spermatozoa are used as a method for storage of genetic materials, however, it is essential to assure the relevance of long-term preservation over several decades or centuries. Thus, we applied the theory of accelerated degradation kinetics to freeze-dried mouse spermatozoa. Thermal denaturation kinetics were determined based on Arrhenius plots derived from transition-state theory analysis at three elevated temperatures: 30, 40, and 50°C. Accelerated degradation kinetics were calculated by extrapolation of Arrhenius plots. This theory also is being applied to the long-term stability of drugs. The estimated rate of development to the blastocyst stage at 3 and 6 mo and at 1, 10, and 100 yr of sperm storage at 4°C were 21.60%, 7.91%, 1.00%, 0%, and 0%, respectively. At −80°C, estimated development rates to the blastocyst stage that would be expected after 10...

Possibility of Long-Term Preservation of Freeze-Dried Mouse Spermatozoa

Study of stability of methotrexate in acidic solution spectrofluorimetric determination of methotrexate in pharmaceutical preparations through acid-catalyzed degradation reaction.

Two integral methods for kinetic parameter estimation with linear temperature profiles were tested using simulated and experimental data sets. They were the second rational approximation method (SRAM) and the equivalent point method (EPM) using least squares nonlinear regression (LSNR) and weighted least squares nonlinear regression (WLSNR). For three simulated data sets, the SRAM with WLSNR yielded accurate parameter estimation. For the experimental data set, both SRAM and EPM using WLSNR yielded accurate parameter estimation. The standard error in activation energy were 37.3% (for SRAM) and 46.7% (for EPM) lower than that of the differential method. The SRAM with WLSNR was the best parameter estimation procedure.

Kinetic Parameter Evaluation with Linearly Increasing Temperature Profiles: Integral Methods

A procedure for prediction of thermal stability of a component in a complex pharmaceutical preparation is outlined. It is based on the reproducibility of the degradation rate function at the various elevated temperatures and extrapolation of the Arrhenius relation to obtain the rate constants that would describe degradation rates at marketing temperatures. The method is applied to the prediction of color stability at shelf temperatures in a liquid multisulfa preparation and the color intensity is predicted at the end of several years by a study completed within a month's time.

Robert F. Carper

Papers

Prediction of Stability in Pharmaceutical Preparations. I. Color Utability in a Liquid Multisulfa Preparation