Phenylbutazone belongs to the non-steroidal anti-inflammatory drug group. It is used to treat inflammation, pain, and fever.
What is phenylbutazone?
Phenylbutazone belongs to the non-steroidal anti-inflammatory drug group. It is used to treat inflammation, pain, and fever. The drug phenylbutazone is used both in human medicine and in veterinary medicine. There, based on pyrazolone, an organic compound, it serves as a non-steroidal anti-inflammatory. Phenylbutazone was developed in 1951 by the Swiss pharmaceutical company Geigy, which now bears the company name Novartis. The active ingredient is suitable for the treatment of pain, inflammation and fever and was the first non-steroidal anti-inflammatory drug to be offered in Germany at the time. However, one disadvantage of the drug is its pronounced side effects. For this reason, phenylbutazone is now used only for acute rheumatoid arthritis, ankylosing spondylitis, and gout attacks.
Pharmacologic action
The most important effect of phenylbutazone is its analgesic and anti-inflammatory properties. The action of the drug is based on the inhibition of prostaglandins. These are tissue hormones that play a significant role in the development of pain, inflammatory reactions and fever. Phenylbutazone can block enzymes such as cyclooxigenase 1 and cyclooxigenase 2. These enzymes are essential for prostaglandin synthesis. In this way, phenylbutazone can exert its analgesic, anti-inflammatory and antipyretic effects. Phenylbutazone is able to remain in the body for a long time. Thus, effective concentrations still occur around three weeks after the drug has been taken. However, strong side effects are also possible due to this effect, so that the intake should not last longer than a few days. If phenylbutazone is administered orally, the drug rapidly enters the blood via the gastrointestinal tract. Within the liver, the substance is broken down to oxyphenbutazone. This substance also has an anti-inflammatory effect. The degradation of phenylbutazone from the organism takes place via the kidneys, whereby it is excreted in the urine. It takes about 50 to 100 hours for 50 percent of the active substance to be eliminated from the body.
Medical use and application
Because of its pronounced side effects, the uses of phenylbutazone are now limited. Thus, the drug is administered exclusively in acute attacks of the chronic inflammatory rheumatoid disease Bekhterev’s disease, acute rheumatoid arthritis, and acute attacks of gout. Phenylbutazone is also used in veterinary medicine for the treatment of animals. There, the drug is administered intravenously, intramuscularly or orally. Percutaneous solutions and ointments are also used. The drug is used in numerous large and small animal practices. However, administration to animals from which food is supplied is prohibited within the EU. Horses are a frequent field of application for the drug. In equestrian sports, however, phenylbutazone is also considered an illegal doping agent. Phenylbutazone is administered to human patients in the form of suppositories, coated tablets, tablets and injectable solutions. The amount of the dose is determined by the attending physician. The recommended starting dose is 600 milligrams of phenylbutazone, while the maintenance dose should not exceed 400 mg per day. In principle, the administration of phenylbutazone should be for a short period of time.
Risks and side effects
Numerous side effects may occur with the use of phenylbutazone. For example, about 20 to 30 percent of patients suffer from adverse side effects. Most cases show diarrhea, nausea, a black discolored stool, pronounced pain in the upper abdomen, unnoticed blood loss, rash and itching of the skin. Likewise, fatigue, dizziness, insomnia, headache, nervousness, decreasing liver enzymes, hepatitis, bile stasis, and the formation of edema are all within the realm of possibility.Rarely occurring side effects include gastrointestinal ulcers, allergic reactions such as asthma attacks, bleeding, anemia (anemia), blood formation disorders associated with fever, flu-like symptoms, sore throat, skin bleeding, inflamed oral mucosa, nosebleeds, and kidney, pancreas, and liver dysfunction. In addition, hypersensitivity reactions may occur that require immediate medical treatment. It is not suitable to take phenylbutazone if the patient suffers from a stomach or intestinal ulcer. If an inflammatory bowel disease such as ulcerative colitis or Crohn’s disease is present, consultation with a physician is necessary. In addition, the drug should be avoided if blood formation disorders such as porphyria are present. The same applies if the patient is already bleeding. Phenylbutazone should not be used during pregnancy. Scientific studies on the use of the drug in this period are not yet sufficient to rule out serious side effects on the embryo. Animal studies have shown indications of malformations. The long residence time of the drug is also considered counterproductive. In the last trimester of pregnancy, there is a risk that phenylbutazone will inhibit labor and cause complications during delivery. Taking phenylbutazone during breastfeeding is also not recommended, as small amounts of the active substance can pass into breast milk. The drug is also not suitable for children. The simultaneous administration of phenylbutazone and other drugs may lead to interactions. Thus, parallel administration of the non-steroidal anti-inflammatory drug and other anti-inflammatory preparations, such as glucocorticoids, may increase the risk of side effects in the gastrointestinal tract. Certain drugs also weaken the beneficial effects of phenylbutazone. These include the antibiotic rifampicin, the cholesterol-lowering agent colestyramine, the barbiturate phenobarbital, the neuroleptic promethazine, and the anti-allergic agent chlorphenamine. Phenylbutazone, on the other hand, can enhance the effect of diabetes drugs, insulin and anticoagulants (anticoagulants). Furthermore, the drug impairs the excretion of methotrexate from the body.
