Quantitative determination and stability of lisuride hydrogen maleate in pharmaceutical preparations using thin-layer chromatography

Abstract

A thin-layer chromatographic (TLC) method has been developed for the determination of lisuride hydrogen maleate (LHM). Lisuride hydrogen maleate [3-(10,10a-didehydro-7-methyl-9α-ergolinyl)-1,1-diethylurea hydrogen maleate] is a substance which has an effect on the CNS. The extraction of the active ingredient from the drugs is performed in a fully automated, electronically controlled extraction apparatus within 2–5 min. The solutions are applied to pre-coated silica gel 60 F254 TLC plates and the separation of the active substance from the inactive ingredient is complete within 20 min. The separated spots are quantified by a thin-layer chromatogram spectrophotometer and the data are processed on-line using a CHB 66/80 computer. The developed chromatographic method is suitable for quality control and for long-term stability studies of LHM in pharmaceutical preparations and can be reproduced with a maximum coefficient of variation of 2.5%. The stability study of LHM in pharmaceutical preparations indicates that this substance is stable only at low temperatures (20 °C). At high temperatures (40, 50 and 60 °C) degradation of LHM occurs after a short storage time. The prediction of the stability study shows that LHM is stable for at least 32 months at 20 °C (room temperature) in solid form. In solutions LHM was completely degraded after a very short time even at 20 °C.