Ammar H O, Ibrahim S A, Abd El-Mohsen M G
Pharmazie. 1982 Apr;37(4):270-1.
The chelating agents NTA, EDTA, HEDTA and DTPA afford a stabilizing action towards isoniazid solutions. The stabilizing effect of the chelating agents is highly dependent on their concentration. The stability of isoniazid solutions increases markedly with increasing NTA or EDTA concentration up to 1 mmol/l. Beyond this concentration, the stabilizing effect of NTA is more or less independent of its concentration and the dependency of the degradation rate of isoniazid on the concentration of EDTA becomes less pronounced. There is an optimum concentration for HEDTA and DTPA at which their stabilizing effect is maximum; below or above this concentration, the stability of isoniazid decreases. The stabilizing efficiency of the investigated chelating agents decreases in the order DTPA greater than HEDTA greater than EDTA greater than NTA, which runs parallel with the stability constants of their metal chelates.
螯合剂NTA、EDTA、HEDTA和DTPA对异烟肼溶液具有稳定作用。螯合剂的稳定效果高度依赖于它们的浓度。异烟肼溶液的稳定性随NTA或EDTA浓度增加至1 mmol/l而显著提高。超过此浓度，NTA的稳定效果或多或少与其浓度无关，而异烟肼降解速率对EDTA浓度的依赖性变得不那么明显。HEDTA和DTPA存在一个最佳浓度，此时它们的稳定效果最大；低于或高于此浓度，异烟肼的稳定性会降低。所研究的螯合剂的稳定效率按DTPA＞HEDTA＞EDTA＞NTA的顺序降低，这与它们金属螯合物的稳定常数平行。
