Das Gupta V, Stewart K R
Am J Hosp Pharm. 1985 Mar;42(3):598-602.
The effect of magnesium sulfate on the stability of penicillin G potassium solutions (0.5 mg/mL) was investigated using a stability-indicating high-performance liquid chromatography method. The penicillin G potassium powder buffered with and without citrate was used. Twelve aqueous duplicate penicillin solutions with various concentrations of magnesium sulfate and with or without buffers were prepared and stored at room temperature. Data on clarity, pH values, and HPLC assay results were determined at intervals during the 10-day storage period. The results indicated that the presence of high concentrations of magnesium sulfate in unbuffered penicillin solutions can cause large pH changes and the degradation of penicillin. However, the effect of magnesium sulfate on the stability of penicillin G potassium was negligible in the buffered solutions. Solutions with a constant pH value of 5.6 prepared using 0.1 M acetate buffer with and without magnesium sulfate showed similar apparent first-order degradation after the 10-day storage period at 24 degrees C. During decomposition, the pH values of the unbuffered solutions decreased for three days and then started increasing in most solutions. The degradation of penicillin G potassium by magnesium sulfate in aqueous solutions resulted from decreases in pH values of the solutions.
采用稳定性指示高效液相色谱法研究了硫酸镁对青霉素G钾溶液（0.5mg/mL）稳定性的影响。使用了添加和未添加柠檬酸盐缓冲的青霉素G钾粉末。制备了十二份含不同浓度硫酸镁且添加或未添加缓冲剂的青霉素水溶液复制品，并在室温下储存。在10天的储存期内定期测定澄清度、pH值和高效液相色谱分析结果。结果表明，未缓冲的青霉素溶液中高浓度硫酸镁的存在会导致pH值大幅变化和青霉素降解。然而，在缓冲溶液中硫酸镁对青霉素G钾稳定性的影响可忽略不计。在24℃下储存10天后，使用含和不含硫酸镁的0.1M醋酸盐缓冲液制备的pH值恒定为5.6的溶液显示出相似的表观一级降解。在分解过程中，未缓冲溶液的pH值下降三天，然后在大多数溶液中开始上升。硫酸镁在水溶液中对青霉素G钾的降解是由于溶液pH值降低所致。
