Process-tolerant manufacturing: An optimization strategy for improving manufacturing yields

In mice depleted of glutathione (GSH) by pretreatment with an inhibitor of GSH synthesis, buthionine sulfoximine (BSO; 1 hr before styrene, 2 mmol/kg or higher doses, ip), styrene (0.96-5.76 mmol/kg, po) produced hepatotoxicity characterized by an increase in serum alanine transaminase activity and cetrilobular necrosis of hepatocytes. Treatment with inhibitors of hepatic cytochrome P-450-dependent monooxygenases such as carbon disulfide, methoxsalen, piperonyl butoxide, and SKF-525A prevented or tended to reduce the hepatotoxic effect of styrene given in combination with BSO. Styrene 7,8-oxide (3.84 mmol/kg, po), a known metabolite of styrene, in combination with BSO caused an earlier and larger increase in SALT than that caused by an equimolar dose of styrene in combination with BSO. These results suggest that metabolism of styrene, possibly to styrene 7,8-oxide, is a necessary step in styrene-induced hepatotoxicity in GSH-depleted mice. Before the onset of hepatotoxicity, styrene in combination with BSO produced a larger and more prolonged depletion of hepatic GSH than that seen after the sole treatment with BSO or prolonged depletion of hepatic GSH than that seen after the sole treatment with BSO or styrene, but no depletion of hepatic protein sulfhydryls was induced by styrene in combination with BSO.