Home Drug Guide Valproic Acid

Drug Guide

Generic Name

Valproic Acid

Brand Names Depakene, Stavzor

Classification

Therapeutic: Anticonvulsant, mood stabilizer

Pharmacological: GABAergic agent

FDA Approved Indications

Epilepsy (absence seizures, partial seizures, generalized seizures)
Bipolar disorder (manic episodes)
Migraine prophylaxis

Mechanism of Action

Valproic acid increases brain concentrations of gamma-aminobutyric acid (GABA), an inhibitory neurotransmitter, thereby stabilizing neuronal activity.

Dosage and Administration

Adult: Initial dose varies; common starting dose is 10-15 mg/kg/day, titrated up to maintenance dose of 60 mg/kg/day in divided doses.

Pediatric: Dosing based on weight; generally 15 mg/kg/day initially, titrated to 60 mg/kg/day.

Geriatric: Start at lower doses due to increased sensitivity and reduced metabolism.

Renal Impairment: Adjust dose accordingly; increased monitoring needed.

Hepatic Impairment: Use with caution; dosage adjustments recommended due to hepatic metabolism.

Pharmacokinetics

Absorption: Well absorbed orally with peak levels in 1-2 hours.

Distribution: Approximately 90% bound to plasma protein.

Metabolism: Primarily hepatic via glucuronidation and mitochondrial beta-oxidation.

Excretion: Renally excreted mainly as metabolites.

Half Life: 15-17 hours in adults; shorter in children.

Contraindications

History of hypersensitivity to valproic acid or other valproates.
Liver disease.

Precautions

Monitor hepatic function, especially during initial treatment.
Risk of pancreatitis; monitor for symptoms.
Use with caution in pregnancy due to teratogenicity.

Adverse Reactions - Common

Nausea, vomiting (Frequent)
Sedation (Frequent)
Hair thinning (Common)

Adverse Reactions - Serious

Hepatotoxicity (Rare but serious)
Pancreatitis (Rare)
Thrombocytopenia (Uncommon)
Weight gain (Common)

Drug-Drug Interactions

Carbamazepine, phenytoin, phenobarbital (may alter levels)
Cimetidine (can increase valproic acid levels)

Drug-Food Interactions

N/A

Drug-Herb Interactions

N/A

Nursing Implications

Assessment: Baseline liver function tests, complete blood count, serum drug levels, and neurologic assessment.

Diagnoses:

Risk for hepatic injury
Impaired skin integrity (rash)
Risk for bleeding

Implementation: Administer with food if GI upset occurs; monitor serum levels regularly; educate patients and families.

Evaluation: Assess seizure control, monitor for side effects, and perform laboratory tests periodically.

Patient/Family Teaching

Advise on the importance of regular blood tests.
Report signs of liver dysfunction (jaundice, abdominal pain).
Use effective contraception during therapy if of childbearing age.
Be aware of possible drowsiness or coordination problems.

Special Considerations

Black Box Warnings:

Hepatotoxicity, especially in children under 2.
Teratogenicity: risk of neural tube defects and other malformations.

Genetic Factors: Polymorphisms in UGT enzymes can affect metabolism.

Lab Test Interference: May affect ammonia levels, liver function tests.

Overdose Management

Signs/Symptoms: Drowsiness, coma, increased seizure frequency, vomiting.

Treatment: Supportive care, airway management, activated charcoal if ingestion recent, and consider hemodialysis in severe cases.

Storage and Handling

Storage: Store at room temperature, away from moisture and light.

Stability: Stable for 2-3 years when stored properly.