Table 1.

Patient case - phenytoin and valproic acid dosing and concentrations.

	Pre-Surgery	2 weeks Post-Operative	5 weeks Post-Operative	9 months Post-Operative	10 months Post-Operative*	11 months Post-Operative*	1 year Post-Operative*	1.5 years Post-Operative
Patient’s weight (kg)	156	148		100				88
Phenytoin Dose	200 mg BID	200 mg BID	250 mg BID	250 mg BID	250 mg BID	250 mg BID	250 mg BID	250 mg BID
Total Phenytoin Concentration (mcg/mL) Therapeutic range: 10–20 mcg/mL	7	5.8	8.5	13.1				15.7
Free Phenytoin Concentration (mcg/mL) Therapeutic range: 1–2 mcg/mL	1.5	1.1	1.4	1.6				3.1
Valproic Acid Dose	1000 mg TID	1000 mg TID	1000 mg TID	1000 mg TID	1500 mg TID	1750 mg TID	1500 mg QID	1500 mg QID
Total Valproic Acid Concentration (mcg/mL) Therapeutic range: 50–125 mcg/mL)	83	66	82	26	39	42	54	62
Free Valproic Acid Concentration (mcg/mL) Therapeutic range: 5–25 mcg/mL	9	15	13	4	3	4	5	5

*No patient weight, phenytoin levels were not available for 10 months, 11 months, and 1 year post-operatively.

Abbreviations: Kg: kilogram, BID: Twice a day, Mcg: microgram, mL: Milliliters, TID: Three times a day.