Allopurinol Contraindications and Precautions
- breast-feeding
- driving or operating machinery
- hepatic disease
- pregnancy
- renal disease
- renal failure
- renal impairment
Allopurinol (Zyloprim) Contraindications and Precautions
Allopurinol (Zyloprim) is classified as pregnancy category C. Adequate studies in pregnant women have not been conducted, so the potential risks to the fetus must be weighed against the potential benefits to the mother. Allopurinol (Zyloprim) and its metabolite oxypurinol are distributed into breast milk. Although the significance to the nursing infant is unknown, allopurinol should be used during breast-feeding only when clearly needed.
An increase in BUN has been observed in some patients with renal disease receiving allopurinol. Patients with renal impairment who are receiving thiazide diuretics in combination with allopurinol are at increased risk for severe skin and hypersensitivity reactions and should be monitored closely. Patients with renal impairment require dosage adjustments (see Dosage). Patients with renal failure may require an extended dosing interval in addition to a dosage reduction. Serious toxicity has occurred in patients who received standard doses in the presence of renal insufficiency (see Adverse Reactions). Patients should maintain a urine output >= 2 L/day to attempt to avoid the formation of xanthine calculi under the influence of allopurinol therapy and to help prevent renal precipitation of urates in patients receiving concurrent uricosuric agents.
Periodic liver-function tests are recommended during the initial stages of allopurinol treatment for patients with hepatic disease. In rare cases, reversible hepatotoxicity has been observed; the incidence of hepatotoxicity increases in patients who also have renal impairment. Asymptomatic increases in serum alkaline phosphatase or serum transaminases also have been reported. However, specific recommendations for allopurinol dosage adjustment in patients with hepatic impairment are not available.
In some patients allopurinol may cause drowsiness. Patients should exercise caution when driving or operating machinery until they know how allopurinol affects them.
[ Last revised: 10/8/2002 12:21:00 PM ]
References
Hande KR, Noone RM, Stone WJ. Severe allopurinol toxicity. Am J Med 1984;76:47-56.
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