Determinations of the content of selected triptanes in drug substance and pharmaceutical dosage forms using gas chromatography and densitometry in the presence of their degradation products

Abstract

Two methods were developed for the determination of naratriptan hydrochloride and sumatriptan. Their degradation products indispensable for validation of the system were obtained by degrading the substances using acid (0.1 M hydrochloric acid), base (0.1 M sodium hydroxide), oxidising agent (30% hydrogen peroxide), heat (105˚C), and VIS irradiation as the degradation agents. The first method consisted in the use of gas chromatography with flame ionisation detector. The best results were acquired using as a stationary base a capillary column HP-1 (10 mm x 0,53 mm i.d. with a film thickness of 2.65 µm) and helium as a mobile phase. The initial temperature, speed of temperature increase, pressure of the carrier gas and internal references were selected. Calibration graphs were linear in the concentration range 50–350 µg/ml (naratriptan hydrochloride) and 10–200 µg/ml (sumatriptan). The second method consisted in the densitometric evaluation of the selected compounds (naratriptan hydrochloride and sumatriptan) in the tablets after former separation using a thin – layer chromatography. Ethyl acetate – methanol – ammonium hydroxide solution (19:2:1 v/v/v) was used as a mobile phase and optical densities were measured at 225 nm (naratriptan hydrochloride) and 226 nm (sumatriptan). Calibration graphs of naratriptan hydrochloride and sumatriptan were linear in the concentration ranges respectively 0.2 – 3 µg and 0.2 - 4µg per spot. The developed methods were successfully applied for determining naratriptan hydrochloride and sumatriptan in drug substances and pharmaceutical dosage forms (Naramig tablets, Imigran suppositories, Sumamigran tablets) and good repeatability and accuracy were proved. The obtained results were subject to analysis and compared with the reference methods, i.e. pharmacopeal HPLC methods.