Nurses Compass
Drug Guide
Allopurinol
Classification
Therapeutic: Antigout agent
Pharmacological: Xanthine oxidase inhibitor
FDA Approved Indications
- Gout prophylaxis
- Lixisenatide (related to gout prevention)
- Kidney stones related to uric acid
- Increased uric acid due to chemotherapy
Mechanism of Action
Inhibits xanthine oxidase enzyme, reducing uric acid production
Dosage and Administration
Adult: Initially 100 mg daily, titrate up to 300-600 mg daily based on serum uric acid levels.
Pediatric: Not typically used in children unless for tumor lysis syndrome, dose individualized.
Geriatric: Start at lower doses due to potential renal impairment.
Renal Impairment: Adjust dose based on renal function; cautious use in severe impairment.
Hepatic Impairment: Use with caution; no specific dose adjustment but monitor liver function.
Pharmacokinetics
Absorption: Well absorbed orally, peak levels in 1-2 hours.
Distribution: Distributed widely, crosses placenta and enters breast milk.
Metabolism: Minimal hepatic metabolism, mostly excreted unchanged.
Excretion: Renally excreted, requires dose adjustment in renal impairment.
Half Life: Approximately 2 hours in healthy individuals, prolonged in renal impairment.
Contraindications
- Hypersensitivity to allopurinol
- Acute gout attacks (should be initiated after attack subsides)
Precautions
- Renal or hepatic impairment
- History of hypersensitivity reactions, including skin reactions
- Risk of severe skin reactions like Stevens-Johnson syndrome (HLA-B*58:01 allele)
Adverse Reactions - Common
- Rash (Common)
- Gastrointestinal upset (Common)
Adverse Reactions - Serious
- Severe skin reactions (Stevens-Johnson syndrome, Toxic epidermal necrolysis) (Rare)
- Hepatotoxicity (Rare)
- Hematologic abnormalities (agranulocytosis, aplastic anemia) (Rare)
Drug-Drug Interactions
- Azathioprine, mercaptopurine (risk of toxicity due to decreased metabolism)
- Theophylline (altered levels)
Drug-Food Interactions
N/ADrug-Herb Interactions
N/ANursing Implications
Assessment: Monitor serum uric acid, renal and liver function, skin for reactions.
Diagnoses:
- Risk for gout attacks during initiation
- Impaired skin integrity
Implementation: Start at low dose, titrate as needed, monitor labs and clinical status.
Evaluation: Serum uric acid levels, renal function, and skin condition.
Patient/Family Teaching
- Take medication with plenty of fluids to prevent kidney stones.
- Report any skin rash or allergic reactions immediately.
- Adhere to scheduled monitoring appointments.
Special Considerations
Black Box Warnings:
- Severe dermatologic reactions, including Stevens-Johnson syndrome, toxic epidermal necrolysis, and hypersensitivity reactions. Increased risk in certain HLA alleles (HLA-B*58:01).
Genetic Factors: HLA-B*58:01 allele screening recommended in certain populations (e.g., Han Chinese, Korean, Thai) before initiation.
Lab Test Interference: Can falsely elevate serum uric acid measurements in some assays.
Overdose Management
Signs/Symptoms: Gastrointestinal symptoms, hypersensitivity reactions.
Treatment: Supportive care, monitor renal function, and consider hemodialysis in severe cases.
Storage and Handling
Storage: Store at room temperature, away from moisture and light.
Stability: Stable under recommended storage conditions.