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At least 163 records · Page 9Linked to original sources
PubMed1995

Fused pyrazine mono-N-oxides as bioreductive drugs. III. Characterization of RB 90740 in vitro and in vivo.

RB 90740 is the lead compound in a series of aromatic mono-N-oxide bioreductive drugs. The compound shows considerably greater toxicity towards hypoxic verses aerobic mammalian cells in vitro. The differential in concentration required to give the same level of cell killing under these conditions ranges from 3.5 in a human bronchio-alveolar tumor cell line up to 120 in a rodent cell line defective in the repair of DNA strand breaks. The ability of RB 90740 to cause DNA strand breaks under hypoxic conditions was confirmed by alkaline sucrose gradient and pulsed field gel electrophoresis techniques. Despite these properties demonstrated in vitro, RB 90740 was shown not to be cytotoxic to hypoxic cells in experimental murine tumors in vivo. This may be due, in part, to the level of hypoxia (< 0.02% O2) necessary to produce toxicity in vitro.

Animals↗
PubMed1988

The metabolism of 5-(4-acetamidophenyl)pyrazin-2(1H)-one in rat, dog and cynomolgus monkey.

1. The metabolism and disposition of 14C-acetamidophenyl pyrazinone has been studied in rat, dog and cynomolgus monkey. The compound was well absorbed and rapidly excreted in urine and faeces by all three species. 2. Distribution of 14C-pyrazinone was rapid and extensive with the exception of the central nervous system where concentrations were at, or below, the limit of detection. 3. Whereas, in in vitro studies, metabolites (but not the parent compound) weakly inhibited some activities of the cytochrome P-450 system, there was evidence from in vivo studies in the rat that the compound and/or its metabolite(s) are weak selective inducers of cytochrome P-450. 4. Metabolite patterns were similar in all three species. The major route of metabolism was glucuronidation at the oxygen of the pyrazinone ring. Other metabolites originated from metabolism by gut microflora with subsequent hepatic metabolism.

Animals↗