Butazolidin
Generic Name: Phenylbutazone
Drug Class: Anti-Inflammatory agent
Indications: Active ankylosing spondylitis, active rheumatoid arthritis, acute attacks of degenerative joint disease specifically of the hips & knees, acute gouty arthritis; short term relief of muscles & tendons; analgesic, fever-reduction; never to be taken casually
Contraindications: history of bronchospasticity reaction to aspirin or other NSAID (nonsteroidal anti-inflammatory drug); pregnancy and/or lactating female as it crosses into the fetal blood circulation and causes birth defects including cardiac abnormalities; may cause prolonged labor.
Possible Adverse Reactions or Side Effects: No long term animal studies have been conducted to determine the carcinogenic pottentials. Animal studies have determined that no person under the age of 15 should take this drug due to possible genetic changes. Supposing (probably scientifically incorrect) 1 year of equine life equals 3 human years, one could determine it should not be given to any horse under the age of 5. Considering the indiscriminate usage of this drug in the equine industry, perhaps this is 1 cause of genetic weakness in the modern day horse. Further adverse reactions reported are: abdominal discomfort & distress, indigestion, abdominal distention with gas formation, constipation, diarrhea, esophagitis, gastritis, salivary gland enlargement, stomatitis often with ulceration, G.I. tract ulceration & perforation, anemia due to occult GI bleeding, hepatitis, aplastic anemia, bone marrow depression, thrombocytopenia, leukopenia, anemia, hemolytic anemia, rash, fluid retention, edema, sodium & chloride retention, congestive heart failure, metabolic acidosis, respiratory alkalosis, hypertension, interstitial myocarditis, renal stones, nephrotic syndrome, renal impairment and/or failure, ureteral obstruction with uric acid crystals, agitation, confusion, lethargy, tremors, numbness, weakness, fever, anaphylactic shock, vasculitis, activation of systemic lupus erythematosus, temporal arteritis, hyperglycemia, hearing loss, etc.
Usage should be restricted during pregnancy due to increases in the stillbirth rates and decrease in surviving offspring found in rats. Clinical studies of horses have been inconclusive or negative regarding chromosomal anomalies. Therefore, the pregnant mare's benefits should greatly outweigh the possible damage risk to the unborn fetus. Breast milk has been found to contain small amounts of the drug. Hence, lactating mares should be restricted from this therapy if possible.
Warnings & Precautions: Usage to be discontinued as soon as possible after the 7th day of therapy; can cause aplastic anemia; may precipitate other dyscrasias including thrombocytopenia or hemorrhagic diathesis; blood reactions may develop abruptly or gradually soon after therapy beins; complete blood laboratory work up including erythrocytes, leukocytes & platelets suggested prior to administration; immediately discontinue usage if sore throat, fever, oral lesions or unusual bruising or bleeding occurs including black or tarry bowel movements; gastrointestinal effects include ulcer, perforation & severe bleeding; renal toxicity may result in protein in the urine, acute interstitial nephritis with bleeding present, & may cause renal failure due to decrease in renal protaglandin formation; drug accumuulation may occur if there is renal impairement; increases socium retention, hence, there may be extremity swellings; visual disturbances include optic neuritis, retinal hemorrhage, oculomotor palsy, etc.; may increase the incidences of stomatitis, pancreatitis, or temporal arteritis; hypothyroidism has been reported in humans
Overdosage: Symptoms of mild poisoning are: abdominal pain, lethargy. Symptoms of severe poisoning in the early stages are: upper abdominal pain, diarrhea, restlessness, dizziness, agitation, hallucinations, coma, convulsions, electrolyte disturbances, alkalosis or acidosis, respiratory arrest, hypo- or hypertension, etc. Symptoms of severe poisoning in late stages (s-7 days) are: acute renal failure, edema, hematuria, jaundice, ECG abnormalities, cardiac arrest, anemia, thrombocytopenia, leukopenia, leukocytosis, seizures, etc.
Drug Interactions: Increased toxicity if used with other anti-inflammatory agents, anticoagulants, sulfonylureas, sulfonamides, phenytoin, valproic acid, lithium, methotrexate, divalproex; Decreased by barbiturates, promethazine, chlorpheniramine, rifampin, prednisone; Increased serum levels if used with methylphenidate; Decreases effectiveness of digitoxin, cortisone; Decreased absorption when used with cholestyramine.
Altered Lab Values: Liver function abnormalities may increase SGOT or SGPT; decreases uric acid levels, elevates glucose levels; no significant changes reported in urinary values when used at therapeutic dosages.
References: 1,2,3