A bottle of acetaminophen/butalbital
|Trade names||Fioricet, others|
|AHFS/Drugs.com||FDA Professional Drug Information|
Acetaminophen/butalbital, sold under the brand name Fioricet among others, is a combination medication used to treat tension headaches and migraine headaches. It contains butalbital, a barbiturate and paracetamol (acetaminophen), an analgesic. Some version also contain caffeine. It is taken by mouth.
The most common side effects include sleepiness, dizziness, trouble breathing, and abdominal pain. Other severe side effects may include liver problems, confusion, addiction, and allergic reactions. Frequent use may result in medication overuse headache. Barbiturate withdrawal may occur if rapidly stopped following long term use. Use is not generally recommended during pregnancy or breastfeeding.
The combination was approved for medical use in the United States in 1984. It is avaliable as a generic medication. In the United States the wholesale cost is about 1.20 USD per dose as of 2019. In 2016 it was the 202nd most prescribed medication in the United States with more than 2 million prescriptions. In the United States it is a schedule III controlled substance. It is banned in a number of European countries.
Acetaminophen/butalbital is indicated for the treatment of tension headaches. It is also commonly prescribed for migraines, although it is not approved by the FDA for this. The usual adult dose is one to two tablets every four hours as needed, not to exceed six tablets in a twenty-four-hour period.
Commonly reported side effects include euphoria, dizziness or lightheadedness, drowsiness or sedation, intoxication, nausea, vomiting, dependence, shortness of breath, and abdominal pain.
Prolonged use can cause rebound headaches.
Butalbital exerts its toxicity through excessive sedation, resulting in respiratory depression and ultimately death via hypoxia. Nonlethal overdoses may also result in coma and death. There is no specific antidote to barbiturate overdose; treatment is supportive, generally including the administration of intravenous saline, naloxone, thiamine, glucose, sodium bicarbonate to alkalize the urine and increase rate of excretion, and activated charcoal via nasogastric tube.
Acetaminophen exerts its toxicity through the production of a toxic metabolite that can cause liver damage at doses as low as four grams. Larger doses can precipitate acute liver failure, acute kidney injury, or gastrointestinal bleeding; death has been known to occur with ingestion of ten to fifteen grams. The specific antidote to acetaminophen overdose is N-acetylcysteine.
Mechanism of action
Butalbital exerts a generalized depressant effect on the central nervous system and, in very high doses, has peripheral effects. Acetaminophen has analgesic and antipyretic effects mediated by a metabolite that acts at cannabinoid receptors.[dubious ] 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 2.5 to 4.5 hours.
Fiorcet historically contained 50 mg of butalbital, 40 mg of caffeine, and 325 mg of acetaminophen per dose. However, in accordance with FDA guidelines advising manufacturers to limit doses of acetaminophen in prescription drugs, the acetaminophen content was lowered to 300 mg as of 2014.
Fioricet is also available in a formulation containing 30 mg of codeine per dose.
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