Release of ergotamine from poly (2‐hydroxyethyl Methacrylate)

Abstract

The release of the alkaloid ergotamine from thin discs of poly(2‐hydroxyethyl methacrylate) [PHEMA] into an aqueous buffered medium has been effected under sink conditions and monitored by fluorescence spectroscopy. The process was found to be diffusion controlled, the fraction of available drug released being linear in (time)^1/2 during the initial stages. The influences of disc thickness, drug load and temperature were investigated and yielded 2.0 (± 1.0) × 10⁻¹³ m² s⁻¹ for the diffusion coefficient of ergotamine through the swollen gel at 310K and a value of 69 ± 5 kJ mol⁻¹ for the activation energy of diffusion. For the uptake of aqueous buffer alone into PHEMA the corresponding values were ca 100 times greater and three times smaller respectively.