Characterization of PEGylation sites in Neulasta and a biosimilar candidate with a combined fragmentation strategy in mass spectrometry analysis.

In the development of biosimilar products to Neulasta, it is essential to determine the intact molecular mass and confirm precise PEGylation sites. In this study, we applied a combination of techniques, including post-column addition of triethylamine in reversed-phase liquid chromatography-mass spectrometry (RPLC-MS) to determine the intact molecular mass, and in-source fragmentation (ISF) and higher-energy collision dissociation-tandem mass spectrometry (HCD-MS/MS) to identify the PEGylation site. Our results show that both the pegfilgrastim biosimilar candidate and Neulasta lots are mono-PEGylated at the N-terminal end.

Characterization of furosemide-induced activation of the renal prostaglandin system.

A detailed time course of changes in plasma renin activity (PRA), urinary prostaglandin (PG) E2, PGF2 alpha, thromboxane (TX) B2 and sodium excretion rates following furosemide was obtained in 7 women. PRA increased within the first 15 min and remained elevated all through the experiment. PGE2, PGF2 alpha, TXB2 and sodium increased simultaneously, reached a peak between 15 and 45 min after furosemide and declined thereafter.

Relationship between kallikrein and PRA after intravenous furosemide.

Interrelationships between plasma renin activity (PRA), urinary kallikrein and sodium excretion were studied before and after furosemide iv administration in nine normal volunteers and in one low renin non hypertensive patient. PRA, urinary kallikrein and sodium excretion increased within 15 min of furosemide injection in nine subjects; kallikrein excretion then decreased sharply, whereas plasma renin activity reached peak values within 15-120 min of stimulation. In low renin subject low basal levels of PRA paralled undetectable values of kallikrein excretion, and PRA and kallikrein excretion showed no increase after furosemide, despite the expected natriuretic response.