What oral tablet dose of valproic acid (sodium valproate) is equivalent to 10 ml of a liquid formulation containing 250 mg per 5 ml?

Valproic Acid Liquid to Tablet Conversion

10 ml of valproic acid 250 mg/5 ml liquid formulation contains 500 mg of valproic acid, which is equivalent to two 250 mg tablets.

Calculation

• The liquid concentration is 250 mg per 5 ml 1
• Therefore, 10 ml contains: (250 mg ÷ 5 ml) × 10 ml = 500 mg
• Each valproic acid capsule contains 250 mg 1
• Equivalent tablet dose: Two 250 mg capsules = 500 mg total

Bioavailability Considerations

• All oral formulations of valproic acid (liquid, tablets, capsules) are almost completely bioavailable, approaching 100% 2, 3
• The different formulations differ primarily in dissolution characteristics and absorption rates, not in total bioavailability 2
• Standard immediate-release formulations have absorption half-lives of less than 30 minutes to 3-4 hours 3

Practical Conversion Guidance

When converting from liquid to tablet formulation:

• Use a 1:1 mg-to-mg conversion (500 mg liquid = 500 mg tablet) 2
• Maintain the same total daily dose and dosing frequency
• Monitor for any changes in seizure control or side effects during the first 1-2 weeks after conversion
• Consider checking valproic acid levels 3-6 months after conversion if clinically indicated 4

Important Monitoring After Conversion

• The therapeutic range for valproic acid is 50-100 μg/mL 5, 6
• Verify medication adherence if breakthrough seizures occur, as non-compliance is the most common cause of subtherapeutic levels 4, 7
• Monitor liver function tests every 3-6 months, particularly in high-risk populations 4