HPLC evaluation of drugs in transdermal therapeutic preparations. I. Glycerol trinitrate

In connection with the development of transdermal delivery systems (TTS) of the laminated adhesive patches type, HPLC was selected for analytical evaluation of active principles. It was employed for analysis of glycerol trinitrate (GTN) as one of the drugs administered in the form of medicinal adhesive patches. After isolation from the patch, GTN was analysed by reverse phase HPLC, employing methanol and water as the mobile phase, and detected at 206 nm. The total amount of GTN in the patch was evaluated and its concentrations in a lactose trituration and the reservoir layer were determined. In the patches manufactured in a test series, the elaborated HPLC method was used to investigate the release of GTN in a liberation study and its permeation through excised human skin in experiments performed in vitro. In connection with the stability study, the decomposition products of GTN were also determined.