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Indications and Dosage
Oral
Rheumatic disorders Adult: Up to 600 mg daily in divided doses. Reduce dose to the lowest effective dose after 1-3 days. Usual max: Up to 1 wk. Oral Acute gout Adult: Up to 800 mg daily may be needed. Reduce to the lowest effective dose after 1-3 days. Usual max duration: Up to 1 wk.
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Administration
Should be taken with food. Take w/ or immediately after meals.
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Contraindications
Active GI bleeding, ulcer disease, pregnancy.
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Special Precautions
CHF, hypertension, renal or hepatic impairment, history of GI disease (bleeding or ulcers), patients receiving anticoagulants, porphyric patients, lactation. Use only when other NSAIDs have failed or discontinue use if no favourable response is seen because of severe hematologic adverse effects. Not recommended for children up to 15 yr.
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Adverse Reactions
Tachycardia, hypotension, myocarditis, atrial fibrillation, atrial flutter, angina, CHF, myocardial depression, pericardial effusion/pericarditis, dizziness, drowsiness, headache, fatigue, seizures, gustatory hallucinations, rash, oedema, erythema multiforme, toxic epidermal necrolysis, cutaneous vasculitis, parotitis, GI disorders, anaemia, thrombocytopenia, coagulopathy, leukopenia, neutropenia, agranulocytosis, granulocytopenia, red blood cell aplasia, hepatitis, primary biliary cirrhosis, vision changes, ototoxicity, tinnitus, renal failure, myoglobinuria, glomerulonephritis, renal vasculitis, pulmonary oedema, pulmonary vasculitis, SLE, lymphadenopathy.
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Overdosage
Abdominal pain, agitation, ataxia, chest pain, cholestatic jaundice, coagulopathy, colitis, coma, dermatitis, diarrhoea, drowsiness, dysosmia, erythema multiforme, exfoliative dermatitis, faecal discolouration, gastritis, haematuria, GI bleeding, hyperventilation, hypotension, hypothyroidism, jaundice, lichenoid eruptions, pemphigus, periarteritis nodosa, pericarditis, photosensitivity, respiratory arrest, rhabdomyolysis, seizures, stomatitis, toxic epidermal necrolysis, urine discolouration. Treatment is supportive; multiple doses of charcoal may be needed to reduce the risk for delayed toxicities.
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Drug Interactions
May reduce phenytoin or warfarin metabolism and methotrexate excretion.
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Action
Description: Phenylbutazone is derived from pyrazolone and is an NSAID used only in acute conditions due to its toxicity. It has anti-inflammatory, antipyretic, uricosuric, and analgesic properties; these actions are due primarily to prostaglandin inhibition, leukocyte migration inhibition, and lysosomal enzyme stabilization.
Onset: 30-60 min. Duration: 3-5 days. Pharmacokinetics: Absorption: Oral: Well absorbed from GI tract. Distribution: Most body tissues and synovial spaces; protein binding: 98%. Metabolism: Hepatic, to oxyphenbutazone and hydroxyphenbutazone; half-life: 50-100 hr (increases with hepatic impairment); time to peak: within 30-60 min. Excretion: Via urine as metabolites (99%). |
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