The Mechanism of Action of Fioricet

The roles and interactions of the combination of acetaminophen, butalbital and caffeine in the treatment of tension headaches are not well understood. But the different mechanisms of action of acetaminophen, or butalbital, or caffeine are well understood.

The mechanism of action of acetaminophen

The mechanisms of action of acetaminophenAcetaminophen:  Acetaminophen acts primarily in the CNS and increases the pain threshold by inhibiting cyclooxygenase, an enzyme involved in prostaglandin (PG) synthesis. Paracetamol (acetaminophen) is generally considered to be a weak inhibitor of the synthesis of prostaglandins (PGs). However, the in vivo effects of paracetamol are similar to those of the selective cyclooxygenase-2 (COX-2) inhibitors. Paracetamol also decreases PG concentrations in vivo, but, unlike the selective COX-2 inhibitors, paracetamol does not suppress the inflammation of rheumatoid arthritis.  Acetaminophen inhibits both isoforms of central cyclooxygenase, COX-1 and COX-2.

Acetaminophen does not inhibit PG synthesis in peripheral tissues, which is the reason for its lack of peripheral anti-inflammatory effects. The antipyretic activity of acetaminophen is exerted by blocking the effects of endogenous pyrogen on the hypothalamic heat-regulating center by inhibiting PG synthesis. Heat is dissipated by vasodilatation, increased peripheral blood flow, and sweating.

The mechanism of action of butalbital

Butalbital (5-allyl-5-isobutylbarbituric acid), a slightly bitter, white, odorless, crystalline powder, is a short to intermediate-acting barbiturate. The mechanism of action of barbiturate is listed below:

The mechanism of action of barbiturate


Butalbital:  Butalbital has generalized depressant effect on central nervous system and, in very high doses, has peripheral effects. Sedative-hypnotic effects of butalbital are similar to phenobarbital and may result from producing or enhancing the inhibitory affects of gamma-aminobutyric acid (GABA) in the thalamus. Barbiturates inhibit ascending conduction in the reticular formation, which interferes with conduction of impulses to the cortex causing sensory cortex depression, decreased motor activity, drowsiness, sedation and changes in cerebral function. Barbiturates also cause a nonselective depressant effect throughout the CNS and are capable of producing all types of CNS mood alterations. In addition, butalbital may exhibit anticonvulsant affects in high, anesthetic doses.

The mechanism of action of Caffeine

The mechanism of action of caffeine

Caffeine is thought to produce constriction of cerebral blood vessels and serves to counteract the sedative effect of butalbital.  Caffeine causes cerebral vasoconstriction, which decreases blood flow and oxygen tension. In combination with acetaminophen, caffeine may provide a quicker onset of action and enhance pain relief allowing for lower doses of analgesics. In some patients, caffeine relieves headaches by treating the effects of caffeine withdrawal.

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 2.5 to 4.5 hours.

Fioricet Cautions and Warnings and What You Must Know Before You Ordering Fioricet Online

Fioricet contains a combination of acetaminophen, butalbital, and caffeine. Butalbital is a short to intermediate-acting barbiturate and is habit-forming and potentially abusable.  Consequently, the extended use of this product is not recommended.

Acetaminophen is used to relieve mild to moderate pain from headaches, muscle aches, menstrual periods, colds and sore throats, toothaches, backaches, and reactions to vaccinations (shots), and to reduce fever. Caffeine is a methylxanthine similar to theophylline and theobromine. While caffeine is used for stimulant and mood-elevating effects in drinks such as coffee, it also has been used to treat neonatal apnea and headaches in combination with other analgesics.

Following image is the ingredient of fioricet.

 the ingredient of fioricet

The average daily dose for the barbiturate addict is usually about 1500 mg.  But the lethal dose of a barbiturate is far less if alcohol is also ingested. It is strictly required not taking alcohol while you are taking fioricet. One of the important ingredient is acetaminophen. A lot of drugs contains acetaminophen.

More than 600 medicines contain acetaminophen. These medicines include both prescription medicines and OTC medicines. On prescription labels, acetaminophen is sometimes listed as “APAP,” “acetam,” or other shorted versions of the word.  Please read very carefully when you are taking the medicines that contains APAP because overdose of acetaminophen will hurt your heart, liver,  and kidney seriously.  To know what is in your medicines, read the list of active ingredients on the label each and every time you take a medicine. Following picture is a list of some OTC or prescription drugs that contain acetaminophen.

drugs that contains acetaminophen

When you take drugs for pain relief. Please check whether the drug contains apap. You cannot take more than 4000mg acetaminophen per day.

Liver Damage While taking Acetaminophen

The safety dosage is 3000mg per day.  Acetaminophen has been associated with cases of acute liver failure, at times resulting in liver transplant and death. Most of the cases of liver injury are associated with the use of acetaminophen at doses that exceed 4000 milligrams per day, and often involve more than one acetaminophen-containing product.  According to the FDA, in the United States there were “56,000 emergency room visits, 26,000 hospitalizations, and 458 deaths per year related to acetaminophen-associated overdoses during the 1990s. Within these estimates, unintentional acetaminophen overdose accounted for nearly 25% of the emergency department visits, 10% of the hospitalizations, and 25% of the deaths.” [1]

Pregnancy and nursing mom warning while taking fioricet
Acetaminophen; butalbital; caffeine components may all be excreted to some extent into breast milk.  According to the manufacturer, because many drugs are excreted in human milk and because of the potential for serious adverse reactions in nursing infants, a decision should be made whether to discontinue nursing or to discontinue the drug. Caffeine can accumulate in the neonate. Chronic barbiturate use while breast-feeding may cause dependence in the neonate. The chronic use of acetaminophen, butalbital, caffeine during breast-feeding is not recommended.

Serious Skin Reactions
Rarely, acetaminophen may cause serious skin reactions such as acute generalized exanthematous pustulosis (AGEP), Stevens-Johnson Syndrome, and toxic epidermal necrolysis (TEN), which can be fatal. Patients should be informed about the signs of serious skin reactions, and use of the drug should be discontinued at the first appearance of skin rash or any other sign of hypersensitivity.

Other warnings
other serious warning is listed in our first page. Following Patients can not buy Fioricet Online. [2]