Fioricet and Esgic are brand name drugs made from a combination of butalbital (a barbiturate, 50 mg), acetaminophen (325 mg), and caffeine (40 mg). They are indicated for the treatment of tension headaches and muscle contraction headaches. Although not indicated, they are commonly used to treat migraines and other pain related ailments. Note that Fioricet (and some other pain medications) are implicated as causing repeat headaches with over-use (see NYT citation below)

Usage and dosage

Fioricet is indicated for the treatment of complex and muscle contraction headaches. It is also commonly prescribed for migraines although it is not FDA indicated for this use. The usual adult dose is 1-2 tablets every four hours as needed, not exceeding six tablets in a 24 hour period.

Fioricet Mechanism of action

Butalbital has generalized depressant effect on central nervous system and, in very high doses, has peripheral effects. Acetaminophen has analgesic and antipyretic effects; its analgesic effects may be mediated through inhibition of prostaglandin synthetase enzyme complex. Caffeine is thought to produce constriction of cerebral blood vessels.

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 3 hours.

Fioricet Side effects

Side effects for any drug are difficult to predict, but commonly reported side effects for Fioricet include:

• Dizziness
• Drowsiness
• Intoxicated feeling
• Light-headedness
• Nausea
• Vomiting
• Sedation
• Addiction
• Shortness of breath
• Abdominal pain

Butalbital, structure presents as 5-allyl-5-isobutylbarbituric acid, is a barbiturate with an intermediate duration of action. It has the same chemical formula as talbutal but a different structure. Butalbital is often combined with other medications, such as paracetamol (acetaminophen) or aspirin, and is commonly prescribed for the treatment of pain and headache. The various formulations combined with codeine are FDA approved for the treatment of tension headaches.

Combinations include:

• Butalbital and paracetamol (acetaminophen) (trade names: Axocet, Bucet, Bupap, Cephadyn, Dolgic, Phrenilin, Phrenilin Forte, Sedapap)
• Butalbital, paracetamol (acetaminophen), and caffeine (trade names: Fioricet, Esgic, Esgic-Plus)
• Butalbital and aspirin (trade name: Axotal)
• Butalbital, aspirin, and caffeine (trade names Fiorinal, Fiormor, Fiortal, Fortabs, Laniroif)
• Butalbital, paracetamol (acetaminophen), caffeine, and codeine phosphate (Fioricet #3 with Codeine)
• Butalbital, aspirin, caffeine, and codeine phosphate (trade name: Fiorinal #3 with Codeine)

Paracetamol (INN) (pronounced /ˌpærəˈsiːtəmɒl, ˌpærəˈsɛtəmɒl/) or acetaminophen (/əˌsiːtəˈmɪnɵfɨn/  ( listen)) (USAN) is a widely used over-the-counter analgesic (pain reliever) and antipyretic (fever reducer). It is commonly used for the relief of fever, headaches, and other minor aches and pains, and is a major ingredient in numerous cold and flu remedies. In combination with non-steroidal anti-inflammatory drugs (NSAIDs) and opioid analgesics, paracetamol is used also in the management of more severe pain (such as postoperative pain).

While generally safe for human use at recommended doses (1000 mg per single dose and up to 4000 mg per day for adults, up to 2000 mg per day if drinking alcohol), acute overdoses of paracetamol can cause potentially fatal liver damage and, in rare individuals, a normal dose can do the same; the risk is heightened by alcohol consumption. Paracetamol toxicity is the foremost cause of acute liver failure in the Western world, and accounts for most drug overdoses in the United States, the United Kingdom, Australia and New Zealand. Paracetamol is derived from coal tar, and is part of the class of drugs known as “aniline analgesics”; it is the only such drug still in use today. It is the active metabolite of phenacetin, once popular as an analgesic and antipyretic in its own right, but unlike phenacetin and its combinations, paracetamol is not considered to be carcinogenic at therapeutic doses.  The words acetaminophen (used in the United States, Canada , Hong Kong and Iran) and paracetamol (used elsewhere) both come from chemical names for the compound: para-acetylaminophenol and para-acetylaminophenol. In some contexts, it is simply abbreviated as APAP, for N-acetyl-para-aminophenol.

It consists of a fixed combination of butalbital, acetaminophen, and caffeine. The role each component plays in the relief of the complex of symptoms known as tension headache is incompletely understood.

Pharmacokinetics

The behavior of the individual components is described below.

Butalbital

Butalbital is well absorbed from the gastrointestinal tract and is expected to distribute to most tissues in the body. Barbiturates in general may appear in breast milk and readily cross the placental barrier. They are bound to plasma and tissue proteins to a varying degree and binding increases directly as a function of lipid solubility.

Elimination of butalbital is primarily via the kidney (59% to 88% of the dose) as unchanged drug or metabolites. The plasma half-life is about 35 hours. Urinary excretion products include parent drug (about 3.6% of the dose), 5-isobutyl-5-(2, 3-dihydroxypropyl) barbituric acid (about 24% of the dose), 5-allyl-5(3-hydroxy-2-methyl-1-propyl) barbituric acid (about 4.8% of the dose), products with the barbituric acid ring hydrolyzed with excretion of urea (about 14% of the dose), as well as unidentified materials. Of the material excreted in the urine, 32% is conjugated.

The in vitro plasma protein binding of butalbital is 45% over the concentration range of 0.5-20 mcg/mL. This falls within the range of plasma protein binding (20%-45%) reported with other barbiturates such as phenobarbital, pentobarbital, and secobarbital sodium. The plasma-to-blood concentration ratio was almost unity, indicating that there is no preferential distribution of butalbital into either plasma or blood cells.

See OVERDOSAGE for toxicity information.

Acetaminophen

Acetaminophen is rapidly absorbed from the gastrointestinal tract and is distributed throughout most body tissues. The plasma half-life is 1.25 to 3 hours, but may be increased by liver damage and following overdosage. Elimination of acetaminophen is principally by liver metabolism (conjugation) and subsequent renal excretion of metabolites. Approximately 85% of an oral dose appears in the urine within 24 hours of administration, most as the glucuronide conjugate, with small amounts of other conjugates and unchanged drug.

See OVERDOSAGE for toxicity information.

Caffeine

Like most xanthines, caffeine is rapidly absorbed and distributed in all body tissues and fluids, including the CNS, fetal tissues, and breast milk.

Caffeine is cleared through metabolism and excretion in the urine. The plasma half-life is about 3 hours. Hepatic biotransformation prior to excretion results in about equal amounts of 1-methylxanthine and 1-methyluric acid. Of the 70% of the dose that is recovered in the urine, only 3% is unchanged drug.

See OVERDOSAGE for toxicity information.

The following drugs can interact with Fioricet. Tell your doctor if you are using any of these:

• an antibiotic;

• a blood thinner such as warfarin (Coumadin);

• isoniazid;

• zidovudine (Retrovir, AZT);

• seizure medication such as phenytoin (Dilantin) or phenobarbital (Luminal, Solfoton);

• gout medications such as probenecid (Benemid) or sulfinpyrazone;

• an MAO inhibitor such as isocarboxazid (Marplan), phenelzine (Nardil), rasagiline (Azilect), selegiline (Eldepryl, Emsam), or tranylcypromine (Parnate);

• steroids such as prednisone, fluticasone (Advair), mometasone (Asmanex, Nasonex), dexamethasone (Decadron, Hexadrol) and others; or

• an antidepressant such as amitriptyline (Elavil, Etrafon), clomipramine (Anafranil), desipramine (Norpramin), imipramine (Janimine, Tofranil), and others.

This list is not complete and there may be other drugs that can interact with Fioricet. Tell your doctor about all your prescription and over-the-counter medications, vitamins, minerals, herbal products, and drugs prescribed by other doctors. Do not start a new medication without telling your doctor.