The effect of the composition of a fixed dose combination on bioequivalence results

The purpose of this work was to develop a new supergeneric product Meloxicam/Omeprazole. Such a combination brings a benefit in terms of decreasing side effects for the patients using meloxicam. The new combination is composed of a meloxicam powder blend (MPB) and omeprazole gastro-resistant pellets (OAP) in hard gelatin capsules. The main tasks were to select the excipients to keep the functional layer of OAP active and to prove the bioequivalence to the original products of meloxicam tablets together with omeprazole capsules. Although dissolution profiles similar to the original product were obtained, the unexpected results of omeprazole low bioavailability in the fed bioequivalence study (BES I) showed the necessity to investigate the formulation in greater depth. A modified more complex dissolution method was developed in order to understand the release of omeprazole under gastric conditions. This method revealed the degradation of omeprazole in the formulation when exposed to the fed conditions because of the increase in microenvironmental pH in the capsule caused by trisodium citrate, commonly used for improving solubility of meloxicam. This pH increase dissolved the gastro-resistant layer of OAP and caused the chemical degradation. To prevent this effect, a trisodium citrate-free formulation was developed. Reformulated capsules passed the repeated fed bioequivalence study (BES II).

Effect of iron overload and iron deficiency on liver hemojuvelin protein

INTRODUCTION

Hemojuvelin (Hjv) is a key component of the signaling cascade that regulates liver hepcidin (Hamp) expression. The purpose of this study was to determine Hjv protein levels in mice and rats subjected to iron overload and iron deficiency.

METHODS

C57BL/6 mice were injected with iron (200 mg/kg); iron deficiency was induced by feeding of an iron-deficient diet, or by repeated phlebotomies. Erythropoietin (EPO)-treated mice were administered recombinant EPO at 50 U/mouse. Wistar rats were injected with iron (1200 mg/kg), or fed an iron-deficient diet. Hjv protein was determined by immunoblotting, liver samples from Hjv-/- mice were used as negative controls. Mouse plasma Hjv content was determined by a commercial ELISA kit.

RESULTS

Liver crude membrane fraction from both mice and rats displayed a major Hjv-specific band at 35 kDa, and a weaker band of 20 kDa. In mice, the intensity of these bands was not changed following iron injection, repeated bleeding, low iron diet or EPO administration. No change in liver crude membrane Hjv protein was observed in iron-treated or iron-deficient rats. ELISA assay for mouse plasma Hjv did not show significant difference between Hjv+/+ and Hjv-/- mice. Liver Hamp mRNA, Bmp6 mRNA and Id1 mRNA displayed the expected response to iron overload and iron deficiency. EPO treatment decreased Id1 mRNA, suggesting possible participation of the bone morphogenetic protein pathway in EPO-mediated downregulation of Hamp mRNA.

DISCUSSION

Since no differences between Hjv protein levels were found following various experimental manipulations of body iron status, the results indicate that, in vivo, substantial changes in Hamp mRNA can occur without noticeable changes of membrane hemojuvelin content. Therefore, modulation of hemojuvelin protein content apparently does not represent the limiting step in the control of Hamp gene expression.