Fioricet Mechanism of Action

Acetaminophen, butalbital, and caffeine is used to relieve tension headaches. Acetaminophen is in a class of medications called analgesics (pain relievers). It works by changing the way the body senses pain. Butalbital is in a class of medications called barbiturates.

It works by having a relaxing effect on the brain and central nervous system (CNS). Caffeine is a CNS stimulant. It works by changing the amounts of certain natural substances in the brain.

• Fioricet is a combination pain reliever (analgesic) containing acetaminophen, butalbital, and caffeine.
• Experts aren’t sure exactly how acetaminophen works, but suspect it may activate descending serotonergic inhibitory pathways in the CNS and other nociceptive pathways (nociceptive pain describes pain from physical or potential damage to the body such as that from a sports injury or dental procedure). Inhibition of the hypothalamic heat-regulating center gives acetaminophen its fever-lowering effect.
• Butalbital belongs to the class of medicines called barbiturates. When used for pain due to tension headaches experts believe it works by relaxing muscle contractions and causing sedation via an enhancement of the inhibitory effects of GABA (a neurotransmitter that regulates communication between brain cells).
• Caffeine is thought to enhance the pain-relieving effects of acetaminophen by up to 40%. In addition, it has vasoconstrictive properties, narrowing blood vessels in the brain thereby decreasing blood flow and oxygen tension (before a headache or a migraine, blood vessels tend to enlarge). This also helps to relieve pain.
• Fioricet belongs to the class of medicines known as barbiturates because it contains butalbital. It may also be called a combination analgesic.