pentobarbital will lower the extent or effect of dexamethasone by impacting hepatic/intestinal enzyme CYP3A4 metabolism. Use Warning/Monitor.pentobarbital will lower the level or outcome of doxorubicin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Warning/Check.In 2009, Nitschke and his spouse have been detained at Heathrow Airport