Overview
11 DESCRIPTION Valproate sodium is the sodium salt of valproic acid designated as sodium 2-propylpentanoate. Valproate sodium has the following structure: C 8 H 15 NaO 2 M.W. 166.2 Valproate sodium occurs as an essentially white and odorless, crystalline, deliquescent powder. Valproate sodium injection, USP is available in 5 mL single-dose vials for intravenous injection.
Mechanism of Action
12 CLINICAL PHARMACOLOGY 12.1 Mechanism of Action Valproate sodium exists as the valproate ion in the blood. The mechanisms by which valproate exerts its therapeutic effects have not been established. It has been suggested that its activity in epilepsy is related to increased brain concentrations of gamma-aminobutyric acid (GABA). 12.2 Pharmacodynamics The relationship between plasma concentration and clinical response is not well documented. One contributing factor is the nonlinear, concentration dependent protein binding of valproate which affects the clearance of the drug. Thus, monitoring of total serum valproate cannot provide a reliable index of the bioactive valproate species.
Indications
- 1 INDICATIONS AND USAGE Valproate sodium injection is indicated as an intravenous alternative in patients in whom oral administration of valproate products is temporarily not feasible in the following conditions: • Monotherapy and adjunctive therapy of complex partial seizures and simple and complex absence seizures; adjunctive therapy in patients with multiple seizure types that include absence seizures ( 1 ) 1.1 Epilepsy Valproate sodium injection is indicated as an intravenous alternative in patients for whom oral administration of valproate products is temporarily not feasible in the...
Common Doses
- 15 mg
- 10 mg
- 60 mg
- 20 mg
Dosage
2 DOSAGE AND ADMINISTRATION Valproate sodium injection is intended for intravenous use only. • Epilepsy o Complex Partial Seizures in Adults and Children 10 years of age or older: Initial dose is 10 to 15 mg/kg/day, increasing at 1 week intervals by 5 to 10 mg/kg/day to achieve optimal clinical response. Maximum recommended dose is 60 mg/kg/day ( 2.1 ). o Simple and Complex Absence Seizures: Initial dose is 10 to 15 mg/kg/day, increasing at 1 week intervals by 5 to 10 mg/kg/day to achieve optimal clinical response. Maximum recommended dose is 60 mg/kg/day ( 2.1 ). 2.
Black Box Warning
WARNING: LIFE THREATENING ADVERSE REACTIONS WARNING: LIFE THREATENING ADVERSE REACTIONS See full prescribing information for complete boxed warning. • Hepatotoxicity, including fatalities, usually during the first 6 months of treatment. Children under the age of two years and patients with mitochondrial disorders are at higher risk. Monitor patients closely, and perform serum liver testing prior to therapy and at frequent intervals thereafter ( 5.1 ) • Fetal Risk, particularly neural tube defects, other major malformations, and decreased IQ ( 5.2 , 5.3 , 5.
Contraindications
- 4 CONTRAINDICATIONS • Valproate sodium injection should not be administered to patients with hepatic disease or significant hepatic dysfunction [see Warnings and Precautions ( 5.1 )] . • Valproate sodium injection is contraindicated in patients known to have mitochondrial disorders caused by mutations in mitochondrial DNA polymerase γ (POLG; e.g., Alpers-Huttenlocher Syndrome) and children under two years of age who are suspected of having a POLG-related disorder [see Warnings and Precautions ( 5.1 )] .
Side Effects
- 6 ADVERSE REACTIONS The following serious adverse reactions are described below and elsewhere in the labeling: • Hepatic failure [see Warnings and Precautions ( 5.1 )] • Birth defects [see Warnings and Precautions ( 5.2 )] • Decreased IQ following in utero exposure [see Warnings and Precautions ( 5.3 )] • Pancreatitis [see Warnings and Precautions ( 5.5 )] • Hyperammonemic encephalopathy [see Warnings and Precautions ( 5.6 , 5.8 , 5.9 )] • Bleeding and other hematopoietic disorders [see Warnings and Precautions ( 5.7 )] • Hypothermia [see Warnings and Precautions ( 5.
Interactions
- 7 DRUG INTERACTIONS • Hepatic enzyme-inducing drugs (e.g., phenytoin, carbamazepine, phenobarbital, primidone, rifampin) can increase valproate clearance, while enzyme inhibitors (e.g., felbamate) can decrease valproate clearance. Therefore increased monitoring of valproate and concomitant drug concentrations and dosage adjustment are indicated whenever enzyme-inducing or inhibiting drugs are introduced or withdrawn ( 7.1 ) • Aspirin, carbapenem antibiotics, estrogen-containing hormonal contraceptives: Monitoring of valproate concentrations is recommended ( 7.