Prediction of Serum-Free and Cerebrospinal Fluid Valproic Acid Levels in Patients With Hypoalbuminemia After Craniotomy

Determination of Free Valproic Acid Concentration in 569 Clinical Samples by LC-MS/MS After Hollow Fiber Centrifugal Ultrafiltration Treatment

OBJECTIVE

To perform therapeutic drug monitoring of total and free plasma valproic acid (VPA) concentrations in clinical samples and to analyze the related factors.

METHODS

The total VPA concentration in plasma was determined by ultrahigh-performance liquid chromatography with precolumn derivatization with α-bromoacetophenone, and the free VPA concentration was determined by liquid chromatography-tandem mass spectrometry after the plasma was treated by hollow fiber centrifugal ultrafiltration. Regression analysis was performed to examine the associations between free plasma VPA, total plasma VPA, and the plasma protein binding rate. The impact of individual situations, outpatient or inpatient factors, and drug combinations on VPA concentrations were examined.

RESULTS

Of the 569 clinical samples, 268 were inpatients and 301 were outpatients, and the total VPA concentration in 138 cases (24.2%) was lower than the effective treatment concentration range; the total and free VPA concentrations in outpatient samples were 11.0% and 26.1% higher than those of inpatients, respectively. There was no linear relationship between the free and total VPA concentrations. The relationship equation between the plasma protein binding rate and free VPA concentrations was as follows: Y = 0.0255X2 - 1.1357X + 97.429 (r = 0.8011). The total and free VPA concentrations were significantly decreased after the coadministration of phenobarbital (83.7% and 64.3% of the control group, P < 0.05) or carbapenem antibiotics (32.0% and 32.7% of the control group, P < 0.05).

CONCLUSIONS

The total VPA concentrations in patients with epilepsy at our hospital was lower than the effective treatment concentration range, which was inadequate for epilepsy control; the total VPA concentrations of outpatients were higher than those of inpatients; as phenobarbital affects VPA metabolism, therapeutic drug monitoring is recommended. Carbapenem antibiotic coadministration with VPA should be avoided because carbapenem antibiotics can lead to the failure of VPA antiepileptic treatment.

A single dose of valproic acid improves neurologic recovery and decreases brain lesion size in swine subjected to an isolated traumatic brain injury

BACKGROUND

We lack specific treatments for traumatic brain injury (TBI), which remains the leading cause of trauma-related morbidity and mortality. Treatment with valproic acid (VPA) improves outcomes in models of severe TBI with concurrent hemorrhage. However, it is unknown if VPA will have similar benefits after isolated nonlethal TBI, which is the more common clinical scenario. The goal of this study was to evaluate the effect of VPA treatment in a preclinical isolated TBI swine model on neurologic outcomes and brain lesion size and to perform detailed pharmacokinetic analyses for a future clinical trial.

METHODS

Yorkshire swine (n = 10; 5/cohort) were subjected to TBI (8-mm controlled cortical impact). An hour later, we randomized them to receive VPA (150 mg/kg) or saline placebo (control). Neuroseverity scores were assessed daily (0 [normal] to 36 [comatose]), brain lesion size was measured on postinjury 3, and serial blood samples were collected for pharmacokinetic studies.

RESULTS

Physiologic parameters and laboratory values were similar in both groups. Valproic acid-treated animals demonstrated significantly better neuroseverity scores on postinjury 1 (control, 9.2 ± 4.4; VPA, 0 ± 0; p = 0.001). Valproic acid-treated animals had significantly smaller brain lesion sizes (mean volume in microliter: control, 3,130 ± 2,166; VPA, 764 ± 208; p = 0.02). Pharmacokinetic data confirmed adequate plasma and tissue levels of VPA.

CONCLUSION

In this clinically relevant model of isolated TBI, a single dose of VPA attenuates neurological impairment and decreases brain lesion size.

Administration of valproic acid in clinically approved dose improves neurologic recovery and decreases brain lesion size in swine subjected to hemorrhagic shock and traumatic brain injury

BACKGROUND

Traumatic brain injury (TBI) and hemorrhage remain the leading causes of death after trauma. We have previously shown that a dose of valproic acid (VPA) at (150 mg/kg) can decrease brain lesion size and hasten neurologic recovery. The current Food and Drug Administration-approved dose of VPA is 60 mg/kg. We evaluate neurologic outcomes and brain lesion size of a single dose of VPA at a level currently within Food and Drug Administration-approved dose in swine subjected to TBI and hemorrhagic shock.

METHODS

Swine (n = 5/group) were subjected to TBI and 40% blood volume hemorrhage. Animals remained in shock for 2 hours before randomization to normal saline (NS) resuscitation alone (control), NS-VPA 150 mg/kg (VPA 150), or NS-VPA 50 mg/kg (VPA 50). Neurologic severity scores (range, 0-32) were assessed daily for 14 days, and brain lesion size was measured via magnetic resonance imaging on postinjury day (PID) 3.

RESULTS

Shock severity and laboratory values were similar in all groups. Valproic acid-treated animals demonstrated significantly less neurologic impairment on PID 1 and returned to baseline faster (PID 1 mean neurologic severity score, control = 22 ± 3 vs. VPA 150 mg/kg = 8 ± 7 or VPA 50 mg/kg = 6 ± 6; p = 0.02 and 0.003). Valproic acid-treated animals had significantly smaller brain lesion sizes (mean volume in mm3, control = 1,268.0 ± 241.2 vs. VPA 150 mg/kg = 620.4 ± 328.0 or VPA 50 mg/kg = 438.6 ± 234.8; p = 0.007 and 0.001).

CONCLUSION

In swine subjected to TBI and hemorrhagic shock, VPA treatment, in a dose that is approved for clinical use, decreases brain lesion size and reduces neurologic impairment compared with resuscitation alone.