Fioricet Mechanism of action

Fioricet is a brand name consisting of a combination of butalbital (a barbiturate), acetaminophen and caffeine which is indicated for the treatment of tension headaches, muscle contraction headaches and post-dural puncture headaches. Although not indicated, they are commonly used to treat migraines and other pain related ailments

Butalbital has generalized depressant effect on central nervous system and, in very high doses, has peripheral effects. Acetaminophen has analgesic and antipyretic effects mediated by a metabolite which acts atcannabinoid receptors, contrary to popular belief it is not an antiinflammatory at safe levels (it becomes toxic at doses above 1,000mg per dose and/or 3,000mg per day). Caffeine is thought to produce constriction ofcerebral blood vessels and serves to counteract the sedative effect of butalbital.


Butalbital has a half-life of about 35 hours. Acetaminophen has a half-life of about 1.25 to 3 hours, but may be increased by liver damage and after an overdose. Caffeine has a half-life of about 5 to 7 hours.