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.
Fioricet Mechanism of Action
Fioricet is a brand name consisting of a combination of butalbital (a barbiturate), APAP and caffeine which is indicated for the treatment of tension headaches, muscle contraction headaches and post-dural puncture headaches. 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.
Each tablet contains the following active ingredients:
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- butalbital USP . . . . . . . . . .50 mg
- acetaminophen USP . . . . 325 mg
- caffeine USP . . . . . . . . . . .40 mg
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Butalbital (5-allyl-5-isobutylbarbituric acid), is a short to intermediate-acting barbiturate.
Butalbital belongs to the group of medicines called barbiturates. Barbiturates act in the central nervous system (CNS) to produce their effects. When butalbital is used for a long time, it may become habit-forming, causing mental or physical dependence. However, people who have continuing pain should not let the fear of dependence keep them from using narcotics to relieve their pain.
Physical dependence may lead to withdrawal side effects if treatment is stopped suddenly. However, severe withdrawal side effects can usually be prevented by gradually reducing the dose over a period of time before treatment is stopped completely. It has the following structural formula:
Acetaminophen (4´-hydroxyacetanilide), is a non-opiate, non-salicylate analgesic and antipyretic. Acetaminophen is used to relieve pain and reduce fever in patients.
It does not become habit-forming when taken for a long time. But acetaminophen may cause other unwanted effects when taken in large doses, including liver damage.
It has the following structural formula: 
Caffeine (1,3,7-trimethylxanthine), is a central nervous system stimulant.Caffeine is a CNS stimulant that is used with pain relievers to increase their effect. It has also been used for migraine headaches. However, caffeine can also cause physical dependence when it is used for a long time. This may lead to withdrawal (rebound) headaches when you stop taking it. It has the following structural formula: 
Inactive Ingredients: crospovidone, FD&C Blue #1 (aluminum lake), magnesium stearate, microcrystalline cellulose, povidone, pregelatinized starch, and stearic acid.