allopurinol

Contraindicated in:

Hypersensitivity;
Presence of HLA-B*58:01 allele (↑ risk of hypersensitivity reactions);
Lactation: Lactation.

Use Cautiously in:

Acute attacks of gout;
Renal impairment (dose ↓ required if CCr <20 mL/min);
Dehydration (adequate hydration necessary);
OB: Safety not established in pregnancy;
Geri: Begin at lower end of dosage range in older adults.

Adv. Reactions/Side Effects ⬆ ⬇

CV: bradycardia, flushing, HF (reported with IV administration), hypertension, hypotension

Derm: rash (discontinue drug at first sign of rash), DRUG REACTION WITH EOSINOPHILIA AND SYSTEMIC SYMPTOMS (DRESS), STEVENS-JOHNSON SYNDROME, TOXIC EPIDERMAL NECROLYSIS, urticaria

GI: diarrhea, hepatitis, nausea, vomiting

GU: hematuria, renal failure

Hemat: bone marrow depression

Neuro: drowsiness

Misc: HYPERSENSITIVITY REACTIONS

Interactions ⬆ ⬇

Drug-drug:

Mercaptopurine and azathioprine↑ bone marrow depressant properties; doses of these drugs should be ↓.
Ampicillin or amoxicillin↑ risk of rash.
May ↑ effects of oral hypoglycemic agents and warfarin.
Thiazide diuretics or ACE inhibitors may ↑ risk of hypersensitivity reactions.
Large doses of allopurinol may ↑ risk of theophylline toxicity.
May ↑ levels and risk of toxicity of cyclosporine.

Availability ⬆ ⬇

(Generic available)

Tablets: 100 mg; 200 mg; 300 mg
Powder for injection: 500 mg/vial

Route/Dosage ⬆ ⬇

Gout

PO (Adults and Children >10 yr): Initially: 100 mg/day; ↑ at weekly intervals based on serum uric acid (not to exceed 800 mg/day). Doses >300 mg/day should be given in divided doses; Maintenance dose: 100–200 mg 2–3 times daily. Doses of ≤300 mg may be given as a single daily dose.

Renal Impairment

(Adults and Children ): CCr 10–50 mL/min:↓ dose to 50% of recommended; CCr <10 mL/min:↓ dose to 30% of recommended.

Secondary Hyperuricemia

PO (Adults and Children >10 yr): 600–800 mg/day in 2–3 divided doses starting 1–2 days before chemotherapy or radiation.
PO (Children 6–10 yr): 10 mg/kg/day in 2–3 divided doses (maximum 800 mg/day) or 300 mg/day in 2–3 divided doses.
PO (Children <6 yr): 10 mg/kg/day in 2–3 divided doses (maximum 800 mg/day) or 150 mg/day in 3 divided doses.
IV (Adults and Children >10 yr): 200–400 mg/m²/day (up to 600 mg/day) as a single daily dose or in divided doses every 8–24 hr.
IV (Children <10 yr): 200 mg/m²/day initially as a single daily dose or in divided doses every 8–24 hr (maximum dose 600 mg/day).

Renal Impairment

(Adults and Children ): CCr 10–50 mL/min:↓ dose to 50% of recommended; CCr <10 mL/min:↓ dose to 30% of recommended.

US Brand Names ⬆ ⬇

Action ⬆ ⬇

Inhibits the production of uric acid by inhibiting the action of xanthine oxidase.

Therapeutic effects:

Lowering of serum uric acid levels.

Classifications ⬆ ⬇

Therapeutic Classification: antigout agents, antihyperuricemics

Pharmacologic Classification: xanthine oxidase inhibitors

Pharmacokinetics ⬆ ⬇

Absorption: Well absorbed (80%) following oral administration.

Distribution: Widely distributed to tissues.

Protein Binding: <1%.

Metabolism/Excretion: Metabolized to oxypurinol, an active compound with a long half-life. 12% excreted unchanged; 76% excreted as oxypurinol.

Half-Life: 1–3 hr (oxypurinol 18–30 hr).

Time/Action Profile ⬆ ⬇

(hypouricemic effect)

ROUTE	ONSET	PEAK	DURATION
PO, IV	1–2 days	1–2 wk	1–3 wk‡

‡Duration after discontinuation of allopurinol.

Patient/Family Teaching ⬆ ⬇

Instruct patient to take allopurinol as directed. Take missed doses as soon as remembered. If dosing schedule is once daily, do not take if remembered the next day. If dosing schedule is more than once a day, take up to 300 mg for next dose.
Instruct patient to continue taking allopurinol along with an NSAID or colchicine and plenty of fluids during an acute gout flare.
Alkaline diet may be ordered. Urinary acidification with large doses of vitamin C or other acids may ↑ kidney stone formation (see Food Sources for Specific Nutrients). Advise patient of need for ↑ fluid intake.
May occasionally cause drowsiness. Caution patient to avoid driving or other activities requiring alertness until response to drug is known.
Instruct patient to report skin rash, blood in urine, influenza symptoms (chills, fever, muscle aches and pains, nausea, vomiting), or symptoms of DRESS to health care professional immediately; skin rash may indicate hypersensitivity.
Advise patient that large amounts of alcohol ↑ uric acid concentrations and may ↓ effectiveness of allopurinol.
Rep: Advise women of reproductive potential to notify health care professional if pregnancy is planned or suspected and to avoid breastfeeding during therapy and for 1 wk after last dose.
Emphasize importance of follow-up exams to monitor effectiveness and side effects.

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Indications ⬇

Contraind./Precautions ⬆ ⬇