Lamotrigine 350 mg Daily Dose: Formulation Type
A 350 mg daily dose of lamotrigine is administered as immediate-release (normal-release) tablets, not extended-release formulation.
Rationale Based on Available Formulations
Extended-release lamotrigine tablets are manufactured in strengths of 25,50,100,200,250, and 300 mg only 1. The FDA-approved extended-release formulation does not include a 350 mg tablet strength.
To achieve a 350 mg daily dose using extended-release tablets, a patient would need to combine multiple tablets (e.g., 300 mg + 50 mg), which is impractical and not the standard prescribing approach for extended-release formulations 1.
Immediate-release lamotrigine allows flexible dosing across a wide range (50–500 mg/day for adjunctive therapy with enzyme-inducing AEDs, and 100–400 mg/day for monotherapy or with valproic acid) 234.
Clinical Context for 350 mg Dosing
Standard maintenance doses for immediate-release lamotrigine range from 100–200 mg/day when co-administered with valproic acid, 300–500 mg/day when combined with enzyme-inducing antiepileptic drugs (carbamazepine, phenytoin, phenobarbital), and 100–400 mg/day for monotherapy 23.
A 350 mg daily dose falls within the typical range for patients receiving enzyme-inducing AEDs or those requiring higher maintenance doses for seizure control or bipolar disorder maintenance 23.
Doses up to 700 mg/day have been studied and tolerated in patients receiving concomitant enzyme-inducing AEDs, demonstrating that 350 mg is well within the safe and effective dosing range for immediate-release formulations 4.
Administration Considerations
Immediate-release tablets should be swallowed whole with water and can be administered once or twice daily depending on the total daily dose and patient tolerability 25.
For a 350 mg daily dose, typical administration would be 175 mg twice daily or 350 mg once daily, depending on individual pharmacokinetics and concomitant medications 26.
Key Pitfall to Avoid
- Do not assume extended-release formulation is available for all dose strengths. Always verify the specific tablet strengths available for extended-release lamotrigine (25,50,100,200,250,300 mg only) before prescribing 1.