Eudragit s

Lactose monohydrate was obtained from Meggle, Wasserburg Germany. Povidone (K25) was acquired from Boai NKY Pharmaceuticals Ltd, Jiaozuo, China, and sodium starch glycolate was obtained from JRS Pharma, Rosenberg, Germany. Magnesium stearate was provided by Peter Greven GmbH & Co. KG, Bad Münstereifel, Germany. Talc was obtained from Ferdinand Kreuzter Sabamühle GmbH, Nürnberg, Germany. Eudragit ® S was purchased from Evonik, Darmstadt, Germany. Maize starch (Amylo N-400 formerly known as Eurylon 6) was purchased from Roquette, Lestrem, France. Polysorbate 80 (tween 80), butan-1-ol, sodium hydroxide were all purchased from Sigma-Aldrich, Buchs, Switzerland. Potassium dihydrogen phosphate, glyceryl monostearate (GMS) and triethyl citrate (TEC) were all purchased from VWR international LTD, Poole, UK. Trifluoroacetic acid and buffer salts used for dissolution buffers preparation were obtained from Sigma-Aldrich, UK. Sodium chloride and di-potassium hydrogen phosphate were obtained from Fisher Chemical. Magnesium sulphate heptahydrate and calcium chloride hexahydrate were obtained from VWR, UK. Sodium bicarbonate was obtained from Sigma Aldrich, UK, while haemin, L-cysteine HCl, vitamin K and resazurin were obtained from Sigma Life Sciences, UK. Bile salts were from Fluka Analytical, UK and FlukaChemika, UK.

Ibuprofen (99.9%) was supplied by Sequoia Research Products Ltd (Pangbourne, UK). Eudragit® E (EuE), Eudragit® RS (EuRS) and Eudragit® S (EuS) were donated by Evonik (Essen, Germany). Absolute ethanol (EtOH) (HPLC grade), acetonitrile (ACN) (HPLC grade), formic acid (98-100%) and phosphate buffer saline tablets (pH 7.0) were all acquired from Fisher Scientific (Loughborough, UK). Propylene glycol (PG) (99%) was purchased from Sigma-Aldrich (Gillingham, UK). Non-porous, non-reinforced, 0.13 cm thick silicone membrane was purchased from Bioplexus (Ventura, USA).