Capillary electrophoresis for the control of impurities of rDNA somatropin.

In the European Pharmacopoeia, the monographs on somatropin, somatropin bulk solution and somatropin for injection prescribe a number of tests including "related substances", "dimer and related substances of higher molecular weight" and "isoform distribution" which are intended to control the levels of impurities in the substance. The aim of this study was to verify the robustness of a new method by capillary electrophoresis and to compare its performance with that of the existing test for "isoform distribution" by isoelectric focusing. It was demonstrated that the capillary electrophoresis method was superior to the method of isoelectric focusing. The interest of the CZE method consists in the resolution of related impurities that might be process specific and/or generated by the expression system.

Inhibition of mast cell histamine release by flavonoids and biflavonoids.

The effect of 11 flavonoids and 4 biflavonoids on the release of histamine from peritoneal rat mast cells induced by compound 48/80 and calcium ionophore A23187 was studied. Dihydroflavonoids (flavanones) and (+)-catechin did not modify histamine release induced by both secretagogues. Flavone, apigenin and cromoglycate inhibited the secretion elicited by compound 48/80 but did not modify the A23187-induced secretion. The effect of kaempferol on the compound 48/80-induced histamine release was biphasic. Low doses (10 (-6) to 10 (-5)M) of the compound potentiated secretion whereas higher doses inhibited histamine secretion. Some of the drugs tested revealed a higher potency as referred to quercetin. Luteolin, a tetrahydroxyflavone and amentoflavone, a biapigenin, exhibited the highest inhibitory effects of mast cell histamine secretion.