Allopurinol Oral : Uses, Side Effects, Interactions, Warnings

Brand Names: Zyloprim
Therapeutic Category: Antigout Agent; Xanthine Oxidase Inhibitor
Dosage Forms: Tablet, Oral
Use: Labeled Indications: Management of primary or secondary gout, Nephrolithiasis, prevention of recurrent calcium stones

Dosing : Adult : Gout, treatment: Initial: 100 mg once daily
Dosage adjustments: Titrate in 100 mg increments every 2 to 4 weeks to achieve the desired serum uric acid level
Maintenance: Doses ≥300 mg/day needed to reach the desired uric acid target; doses up to 800 mg/day may be required
Maximum: 800 mg/day

Dose Adjustments
Renal Impairment: CrCl ≤60 mL/minute: Oral: Initial: <1.5 mg per unit of eGFR. Doses increased in increments of ≤50 mg/day at intervals of every 4 weeks to the minimum daily dose necessary to achieve the goal urate-lowering effect
Hepatic Impairment: no dosage adjustments
Adverse Drug Interaction:
skin rash, Nausea , vomiting, Renal failure syndrome, renal insufficiency
Pharmacodynamics/Kinetics:
Onset of action: Gout: Decrease in serum and urine uric acid: 2 to 3 days; peak effect: 1 week or longer
Absorption: Oral: 90% from GI tract
Bioavailability: 49% to 53%
Half-life elimination: Parent drug: 1 to 2 hours; Oxypurinol: 15 hours
Time to peak, plasma: Oral: Allopurinol: 1.5 hours; Oxypurinol: 4.5 hours

Important Notes:
Bone marrow suppression reported in patients receiving allopurinol
May occasionally cause drowsiness; patients cautioned about performing tasks that require mental alertness
Pregnancy & Lactation: crosses the placenta / present in breast milk
Medication Safety issue:
- Allopurinol confused with Apresoline
- Zyloprim confused with zolpidem, ZORprin, Zovirax