Valproic Acid TDM

Valproic acid pharmacokinetic dosing and therapeutic monitoring with adjustments for enzyme induction, liver disease, and nonlinear protein binding.

kg

Use ideal body weight for obese patients

years

Mania allows higher target range (50-125 mcg/mL)

Bioavailability: IR=1.0, ER=0.9, IV=1.0

Phenytoin, carbamazepine, phenobarbital increase clearance ~2-fold

Valproate is contraindicated in severe hepatic disease

mg/day
mcg/mL

Steady-state level (typically 2-4 days after starting)

g/dL

Hypoalbuminemia increases free fraction

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References

  1. Valproic Acid - StatPearls — NCBI Bookshelf (2024). https://www.ncbi.nlm.nih.gov/books/NBK559112/
  2. Valproic Acid Dosage Guide + Max Dose, Adjustments — Drugs.com (2024). https://www.drugs.com/dosage/valproic-acid.html
  3. The Pharmacology of Parenteral Valproate — PMC (2004). https://pmc.ncbi.nlm.nih.gov/articles/PMC321191/
  4. TDM OF Valproic Acid — University Lecture (2025). https://www.uomustansiriyah.edu.iq/media/lectures/4/4_2025_04_07!04_31_06_PM.pdf