Age

Dose

1-9 years^a

5 mg/kg once daily, or divided, twice daily, total daily dose not to exceed 150 mg

10-64 years

200 mg once daily, or divided twice daily^b,c

≥ 65

100 mg once daily^d

Renal impairment

80 mL/min

100 mg twice daily

100 mg once daily

60-79 mL/min

Alternating daily doses of 200 mg and 100 mg

Alternating daily doses of 100 mg and 50 mg

40-59 mL/min

100 mg once daily

100 mg every 2 days

30-39 mL/min

200 mg twice weekly

100 mg twice weekly

20-29 mL/min

100 mg three times/week

50 mg three times/week

10-19 mL/min

Alternating weekly doses of 200 mg and 100 mg

Alternating weekly doses of 100 mg and 50 mg

1. Use in children age < 1 year has not been evaluated adequately.

2. Reduction of dosage to 100 mg/day is recommended for people with a seizure disorder, because they may be at risk for more frequent seizures when the dosage is 200 mg/day.

3. For children who are age > 10 years, but who weigh < 40 kg, a dosage of 5 mg/kg/day is advised regardless of age.

4. The reduced dosage is recommended to minimize the risk of toxic effects, because renal function generally declines with age, and side effects have been reported more frequently in the elderly.

Calculation of estimated creatinine clearance: