150-600 mg daily in 2 or 3 divided doses. 
Neuropathic pain Initially 150 mg daily given as 2 or 3 divided doses, may be increased to 300 mg daily after an interval of 3-7 days. Max: 600 mg daily after an additional 7-day interval. 
Epilepsy Initially 150 mg daily given as 2 or 3 divided doses, may be increased to 300 mg daily after 1 wk. Max: 600 mg daily after an additional wk. 
GAD Initially 150 mg daily, may be increased to 300 mg daily after 1 wk. Following an additional wk, may be increased to 450 mg daily. Max: 600 mg daily after an additional wk. 
Renal impairment CrCl ≥60 mL/min 150 mg bid or tid. Max: 600 mg daily; 
≥30-<60 mL/min 75 mg bid or tid. Max: 300 mg daily; 
≥15-<30 mL/min 25-50 mg once daily or bid. Max: 150 mg daily; 
<15 mL/min 25 mg once daily. Max: 75 mg daily. 
Supplementary dose following haemodialysis 25 mg as a single dose. Max: 300 mg daily.