VALPROIC ACID
(Depakene, (also see divalproex))Standard Prescription
valproic acid__mg PO/IV Q__H (__mg/kg/24hr)
Dosages
TID dosing may be required for some patients for tolerability or achieving target serum levels.
Seizures:
Children:
Increase by: 125-250 mg/dose PO/IV BID every 5-7 days
Maintenance: 500-1000 mg/dose PO/IV BID
Maximum: 1500 mg/dose PO/IV BID
Refractory status epilepticus:
30-40 mg/kg/dose IV (Max: 3000 mg/dose)
(Consider lower dose if patient already on maintenance therapy)
Seizures:
Children:
Initial: 2.5-5 mg/kg/dose PO/IV BID
Increase by: 2.5-5 mg/kg/dose PO/IV BID every 5-7 days
Maintenance: 10-15 mg/kg/dose PO/IV BID
PR: 10-15 mg/kg/dose Q8HMaximum: 20-30 mg/kg/dose PO/IV BID or 1500 mg/dose PO/IV BID, whichever is less (Use higher maximum of 60 mg/kg/24 hr only in rare cases, based on individual clinical response)
Adolescents:
Initial: 125-250 mg/dose PO/IV BIDIncrease by: 125-250 mg/dose PO/IV BID every 5-7 days
Maintenance: 500-1000 mg/dose PO/IV BID
Maximum: 1500 mg/dose PO/IV BID
Refractory status epilepticus:
30-40 mg/kg/dose IV (Max: 3000 mg/dose)
(Consider lower dose if patient already on maintenance therapy)
Mechanism of Action
Anticonvulsant
Forms Supplied
capsule: 250 mg
enteric coated capsule: 500 mg
syrup: 50 mg/mL
IV: 100 mg/mL (Available through Health Canada Special Access Programme only)
Comments
Hazardous drug. Refer to Hazardous Drug Handling Policy in PHSA SHOP
Avoid in mitochondrial/urea cycle disorders.
Effective as a mood stabilizer in bipolar disorder and for migraine prophylaxis - see divalproex.
Do not chew or crush enteric coated capsule.
Can give PR as a retention enema (use valproic acid syrup diluted 1:1 with water).
IV administration rate up to 1.5-3 mg/kg/min see IV manual.
Dose related adverse effects: GI upset, drowsiness, tremor, weight gain, thrombocytopenia, hair loss.
Idiosyncratic adverse effects: hepatotoxicity , pancreatitis, hyperammonemia.
Associated with Polycystic Ovarian Syndrome in reproductive age females.
Monitor CBC and liver function at baseline and periodically.
Substrate of CYP 2C9, 2C19; inhibits CYP 2C9, 2C19; highly protein bound. Check for drug Interactions.
Post load (valproic acid) level to be taken 1 hour after IV load or 3 hours after PO load.
Target Level: 350-700 micromoles/L.
See Therapeutic Drug Monitoring in References and Supplementary (white pages in hard copy).
Avoid in mitochondrial/urea cycle disorders.
Caution in < 2 yrs old: increased risk of hepatic failure, particularly in those with undiagnosed inborn errors of metabolism.
Teratogenic: Risk of significant congenital malformations if taken during pregnancy
Effective as a mood stabilizer in bipolar disorder and for migraine prophylaxis - see divalproex.
Do not chew or crush enteric coated capsule.
Can give PR as a retention enema (use valproic acid syrup diluted 1:1 with water).
IV administration rate up to 1.5-3 mg/kg/min see IV manual.
Dose related adverse effects: GI upset, drowsiness, tremor, weight gain, thrombocytopenia, hair loss.
Idiosyncratic adverse effects: hepatotoxicity , pancreatitis, hyperammonemia.
Associated with Polycystic Ovarian Syndrome in reproductive age females.
Monitor CBC and liver function at baseline and periodically.
Substrate of CYP 2C9, 2C19; inhibits CYP 2C9, 2C19; highly protein bound. Check for drug Interactions.
Post load (valproic acid) level to be taken 1 hour after IV load or 3 hours after PO load.
Target Level: 350-700 micromoles/L.
See Therapeutic Drug Monitoring in References and Supplementary (white pages in hard copy).
References
44, 83, 336, 337, 338, 556, 557
Last Edited
2022-09-13 06:25:08