What Is Phenazone?

Phenazone, also called phenazon, is an analgesic, a type of medication used to relieve pain. It also functions as an anti-inflammatory medication and an antipyretic, meaning that it can alleviate fevers. This medication is part of a class of drugs called non-steroidal anti-inflammatories (NSAIDs), which include more well-known compounds like ibuprofen and acetaminophen. Often available as a tablet for oral consumption in many countries, it is also found in Europe in the form of ear drops, usually combined with a local anesthetic like lidocaine to treat earaches.

Many NSAIDs have relatively short half-lives, a term describing the length of time taken to clear half of an ingested drug from the body. Usually, the half-life of an NSAID ranges from six to eight hours. Phenazone has a longer half-life of up to 12 hours, making it a potentially favorable treatment option for persistent, moderate pain.

Pain from migraines in particular is well-suited for treatment with phenazone. A study on patients with recurring migraines found that about half of these individuals had their pain significantly reduced two hours after taking 1000 milligrams (mg) of this medication. About one-quarter of the patients had their pain disappear entirely after using it. Migraines cannot always be treated easily with over-the-counter pain relievers, making this particular drug an effective treatment option.

The risks of phenazone are similar to the risks carried by other NSAIDs, and they can include stomachaches, nausea, and allergic reactions. Allergic reactions to this medication generally occur as a result of a more general allergy to a class of chemicals called pyrazolones that phenazone belongs to. Like some other NSAIDs, this drug can also cause damage to the liver. When taken in normal therapeutic doses, liver toxicity isn't usually a problem, but it becomes a risk if taken in high doses, over long periods of time, or when consuming alcohol frequently.

Phenazone may sometimes occur in preparations with other medications, such as theophylline. In elderly patients, there may be an interaction with these two medications, however, which can change the dosages needed. A study found that administering theophylline sped up the rate that some patients metabolized phenazone, making the pain reliever less effective and shorter-acting. Patients that were less healthy were more prone to this effect occurring. The increased metabolism of this medication seemed to be due to a drug interaction occurring in the liver, which could potentially occur with similar medications such as caffeine, as well.