Phenylbutazone is a non-steroidal anti-inflammatory drug with potent effects for treating the different inflammatory conditions in different domestic animal species.
Let’s know more about Phenylbutazone in this article, which includes:
What is phenylbutazone?
Mechanism of action of phenylbutazone.
General Use of Phenylbutazone.
Uses of Bute in horses
phenylbutazone uses in dogs.
Recommendations for Phenylbutazone use.
Drug Interactions of Phenylbutazone.
Side effects of phenylbutazone.
Precautions and storage of Phenylbutazone.
What is phenylbutazone?
It is a non-steroidal anti-inflammatory drug (NSAID) and cyclooxygenase inhibitor.
It has a potent pain-relieving effect, antipyretic, and anti-inflammatory of soft tissues, muscles, and bones.
It is given intravenously or orally; pain relief and fever reduction usually start within one to two hours.
Mechanism of action of phenylbutazone:
It is a synthetic, pyrazolone derivative which is a nonhormonal, anti-inflammatory, antipyretic compound.
It can be useful in the management of inflammatory conditions as it binds to prostaglandin H synthase inhibiting it, and prostacyclin synthase through peroxide (H2O2) mediated deactivation.
Prostaglandins act on many body cells, such as :
Vascular smooth muscle cells cause constriction or dilation.
Platelets, causing cell aggregation or disaggregation.
Spinal neurons cause pain.
Prostacyclin causes vascular constriction and platelet disaggregation.
General Use of Phenylbutazone:
Phenylbutazone is prescribed to treat fever, inflammation, and pain that results from:
Injury, gout, and osteoarthritis.
Ankylosing spondylitis.
Musculoskeletal disorders.
Use of Bute in Horses:
Phenylbutazone (Bute) is commonly used for the treatment of horse suffering:
Lameness resulting from the soft-tissue injury.
Muscle soreness.
Bone and joint problems.
Laminitis.
Fever, but the antipyretic property can mask other symptoms.
Phenylbutazone preparations for horses include:
1-gram tablets.
Oral powder or oral paste.
Injectable Syringes (containing 6 grams or 12 grams/syringe)
100ml vials providing a dose of 200 mg/ml.
Bute is one of the most common drugs used for horses. Therefore, all vets should be well aware of the health risks associated with Phenylbutazone and its potential interactions.
Phenylbutazone uses In dogs:
Phenylbutazone is usually used in dogs to control chronic pain, such as musculoskeletal pain and osteoarthritis.
The safety margin of Phenylbutazone is as narrow as all NSAIDs in the dog.
The most common anti-inflammatory drugs used in dogs (etodolac and carprofen).
Gastrointestinal-protectant drugs are frequently included as a part of treatment with any NSAID.
The renal monitoring and regular blood work should be considered after the chronic therapy of Phenylbutazone for dogs.
In other animals, due to the availability of safer and more effective options, this medication is rarely used in small animals and farmed animals.
Recommendations for Phenylbutazone using
Oral products are the most common form of administration and are often mixed with various flavors to improve their palatability.
The maximum dosage is 4 grams/day.
Phenylbutazone should be administered intravenously or orally.
Accidental injection into the artery, rather than the vein, may cause seizures.
Interactions of Phenylbutazone with Other Medications:
The following medications should be used with caution when given with phenylbutazone:
Sulfonamides.
Hepatotoxic drugs.
Any other anti-inflammatory drugs, especially corticosteroids, to avoid gastrointestinal ulcers.
Drugs that affect the serum levels and duration of action of oral anticoagulants.
Potassium-sparing diuretics.
penicillamine, penicillin G, as it increases the plasma half-life (slows the breakdown) of penicillin G.
Loop diuretics as furosemide.
Phenylbutazone and oxyphenbutazone also interact with thyroid function tests.
Other drugs as methotrexate, misoprostol, phenobarbital, tricyclic antidepressants, selective serotonin reuptake inhibitors (SSRIs), or warfarin.
Side effects of phenylbutazone.
Effects of gastrointestinal damage include:
Loss of appetite.
Excessive thirst.
Weakness and weight loss.
Kidney failure and death in advanced cases.
Also, Phenylbutazone has many other serious side effects, including:
Skin sores on the face and inside the mouth.
Abnormal urination.
Changing the color of the skin, gums, or eyes into a yellowish color.
Swelling of the legs, weight loss,
Behavior changes.
Abnormal bleeding.
Liver or kidney problems such as water retention.
It can be passed to the embryo via the placenta, causing toxicity.
Precautions and storage of phenylbutazone:
Phenylbutazone should not be administered to animals with serious hepatic, renal or cardiac pathology, or those with a history of blood dyscrasia.
Overdoses can cause:
Kidney failure.
Liver injury.
Bone marrow suppression.
Gastric ulceration or perforation.
Early signs of toxicity include loss of appetite and depression.
The perfect storage conditions of Phenylbutazone include:
Store the oral form in a tight container.
Keep the containers at room temperature, between 15 – 30 °C.
Keep the injectable form in the refrigerator between 8 – 15 °C.
Finally, although Phenylbutazone is very common and effective in horses, be aware of its side effects and overdose.
Written by: Dr. Mai Foda
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