This mechanism is most likely with the induction of hepatic microsomal enzymes that metabolize the antibiotic. If phenobarbital and doxycycline are administered concurrently, the clinical reaction to doxycycline should be monitored intently. Phenytoin, sodium valproate, valproic acid: The effect of barbiturates on the metabolism of phenytoin seems to be variable. https://gunnernvuvr.pointblog.net/the-fact-about-nembutal-that-no-one-is-suggesting-69091665