Fioricet contains a combination of acetaminophen, butalbital, and caffeine. Acetaminophen is a pain reliever and fever reducer. Butalbital is in a group of drugs called barbiturates. It relaxes muscle contractions involved in a tension headache.
Caffeine is a central nervous system stimulant. It relaxes muscle contractions in blood vessels to improve blood flow.
Fioricet is used to treat tension headaches that are caused by muscle contractions.
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 at cannabinoid 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 of cerebral 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