HPLC-MS characterisation of chelate modified somatropin

Somatropin is a recombinant human growth hormone, consisting of 191 amino acids. This protein is clinically used in children and adults with inadequate endogenous growth hormone to stimulate a normal bone and muscle growth. In addition, somatropin is currently being investigated for the diagnosis and radiotherapy of certain hormonal cancers. The modification of the protein with the chelating agent NOTA (1,4,7-triazacyclononane-1,4,7-triacetic acid) allows the inclusion of metals coupled to the protein for diagnostic (e.g. 68Ga) or therapeutic (e.g. 90Y) purposes. The NOTA unit is selectively introduced on a lysine side chain. This yields 9 possible labelling sites for somatropin: FPTIPLSRLFDNAMLRAHRLHQLAFDTYQEFEEAYIPKEQKYSFLQNPQTSLCFSESIPTPSNREETQQKSNLELLRISLLLIQSWLEPVQFLRSVFANSLVYGASDSNVYDLLKDLEEGIQTLMGRLEDGSPRTGQIFKQTYSKFDTNSHNDDALLKNYGLLYCFRKDMDKVETFLRIVQCRSVEGSCGF We have applied an enzymatic digestion procedure for the characterisation of the modified somatropin, using trypsin, chymotrypsin and Staphylococcus aureus V-8 proteases. The resulting peptides were then monitored using HPLC-MS2, allowing the characterisation of the modified protein

Qbd analytical development of calcitonin bioadhesive formulation

Calcitonin is a 32-amino acid polypeptide hormone ubiquitous in humans and animals. It acts i.a. to reduce blood calcium (Ca2+), opposing the effects of parathyroid hormone (PTH). Both human (hu) and salmon (sa) calcitonins are clinically effective and currently approved as active pharmaceutical ingredients (APIs). A new bioadhesive nasal formulation is currently under development, which contains low dose calcitonin in polymeric excipients (carbomer and starch). The analytical development is confronted with several challenges: the low dose of the peptide in the formulation, its inherent instability, the polymeric matrix interacting with the peptide influencing sample preparation and its undefined degradation impurity profile in this formulation. The aim of this investigation was to develop a suitable method to determine the concentration of sa-calcitonin in this formulation and to establish its degradation profile, using experimental designs which will also give us mechanistic information. Degradation profiling was developed towards the sensitive detection of all possible already-identified related compounds [1], using a selective gradient FA-based RP-HPLC with ESI/iontrap MS detection in the SIM mode The assay was developed using Onion and Plackett-Burman designs, evaluating and optimizing the sample treatment procedure. The chromatography method is based on a TFA-based gradient RP-HPLC with UV detection for quantification. Both methods are applied in short-term stability studies for the release of clinical trial material