• The sustained-/extended-release formulations should not be interchanged with the immediate-release products.

Partial Seizures

• PO (Adults and Children >12 yr): 300 mg 3 times daily initially. Titration may be continued until desired effect achieved (range is 900–1800 mg/day in 3 divided doses; dosage interval should not exceed 12 hr). Doses up to 2400–3600 mg/day have been well tolerated.
• PO (Children ≥5–12 yr): 10–15 mg/kg/day in 3 divided doses initially titrated upward over 3 days to 25–35 mg/kg/day in 3 divided doses; dosage interval should not exceed 12 hr (doses up to 50 mg/kg/day have been used).
• PO (Children 3–4 yr): 10–15 mg/kg/day in 3 divided doses initially titrated upward over 3 days to 40 mg/kg/day in 3 divided doses; dosage interval should not exceed 12 hr (doses up to 50 mg/kg/day have been used).

Renal Impairment

• PO (Adults and Children >12 yr): CCr 30–59 mL/min: 200–700 mg twice daily; CCr 15–29 mL/min: 200–700 mg once daily; CCr 15 mL/min: 100–300 mg once daily; CCr <15 mL/min:↓ daily dose in proportion to CCr.

Postherpetic Neuralgia

• PO (Adults ): Immediate release: 300 mg once daily on Day 1, then 300 mg twice daily on Day 2, then 300 mg 3 times daily on Day 3; may titrate as needed up to 600 mg 3 times/day; Sustained release (Gralise): 300 mg once daily on Day 1, then 600 mg once daily on Day 2, then 900 mg once daily on Days 3–6, then 1200 mg once daily on Days 7–10, then 1500 mg once daily on Days 11–14, then 1800 mg once daily thereafter; Extended release (Horizant): 600 mg once daily in the morning on Days 1–3, then 600 mg twice daily thereafter.

Renal Impairment

• PO (Adults ): CCr 30–59 mL/min: 200–700 mg twice daily (immediate release); 600–1800 mg once daily (sustained release [Gralise]); 300 mg once daily in the morning on Days 1–3, then 300 mg twice daily thereafter (may ↑ to 600 mg twice daily, as needed) (extended release [Horizant]); CCr 15–29 mL/min: 200–700 mg once daily (immediate release); sustained release (Gralise) not recommended; 300 mg in the morning on Days 1 and 3, then 300 mg once daily in the morning thereafter (may ↑ to 300 mg twice daily, as needed) (extended release [Horizant]); CCr 15 mL/min: 100–300 mg once daily (immediate release); sustained release (Gralise) not recommended; CCr <15 mL/min:↓ daily dose in proportion to CCr (immediate release); sustained release (Gralise) not recommended; 300 mg every other day in the morning (may ↑ to 300 mg once daily in the morning, as needed) (extended release [Horizant]); CCr <15 mL/min (on hemodialysis): 300 mg after each dialysis session (may ↑ to 600 mg after each dialysis session, as needed) (extended release [Horizant]).

Restless Legs Syndrome

• PO (Adults ): Extended release (Horizant): 600 mg once daily at 5 pm.

Renal Impairment

• (Adults ): CCr 30–59 mL/min: 300 mg once daily at 5 pm; may ↑ to 600 mg once daily at 5 pm as needed; CCr 15–29 mL/min: 300 mg once daily at 5 pm; CCr <15 mL/min: 300 mg every other day; CCr <15 mL/min (on hemodialysis): Not recommended.

Neuropathic Pain (unlabeled use)

• PO (Adults ): 100 mg 3 times daily initially. Titrate weekly by 300 mg/day up to 900–2400 mg/day (maximum: 3600 mg/day).
• PO (Children ): 5 mg/kg/dose at bedtime initially; then ↑ to 5 mg/kg twice daily on Day 2 and 5 mg/kg 3 times daily on Day 3. Titrate to effect up to 8–35 mg/kg/day in 3 divided doses.