From the FDA Drug Label
Because of reports of thrombocytopenia, inhibition of the secondary phase of platelet aggregation, and abnormal coagulation parameters, (e.g., low fibrinogen), platelet counts and coagulation tests are recommended before initiating therapy and at periodic intervals. The probability of thrombocytopenia increases significantly at total trough valproate plasma concentrations above 110 μg/mL in females and 135 μg/mL in males. It is recommended that patients receiving valproic acid be monitored for platelet count and coagulation parameters prior to planned surgery In patients who develop unexplained lethargy, vomiting, or changes in mental status, hyperammonemic encephalopathy should be considered and an ammonia level should be measured. Asymptomatic elevations of ammonia are more common and when present, require close monitoring of plasma ammonia levels.
The lab tests indicated for monitoring Depakote (valproate) therapy are:
- Platelet counts: before initiating therapy and at periodic intervals
- Coagulation tests: before initiating therapy and at periodic intervals
- Ammonia levels: in patients who develop unexplained lethargy, vomiting, or changes in mental status, and in cases of asymptomatic elevations of ammonia
- Valproate plasma concentrations: to determine whether or not they are in the usually accepted therapeutic range (50 to 100 μg/mL) 1
From the Research
Introduction to Depakote (Valproate) Therapy Monitoring
Depakote, also known as valproate, is a medication used to treat various conditions, including epilepsy and bipolar disorder. Monitoring valproate therapy is crucial to ensure its effectiveness and minimize potential adverse effects.
Indicated Lab Tests for Monitoring Valproate Therapy
Lab tests are essential for monitoring valproate therapy, particularly to detect potential liver damage and other adverse effects. According to 2, routine liver function tests may be especially important during valproate therapy because some cases of valproate-induced hepatic failure are the result of chronic liver damage and cirrhosis.
Liver Function Tests
Liver function tests, including measurements of hepatic enzymes, are recommended to monitor for potential liver damage. However, as noted in 3, isolated changes in standard laboratory liver parameters are not reliable early indicators of valproate-associated liver failure.
Therapeutic Drug Monitoring (TDM)
TDM is also an important aspect of valproate therapy monitoring. As stated in 4, the therapeutic range for valproate is between 50 to 100 mg/L, and TDM can help ensure that plasma concentrations remain within this range. TDM can be performed using various methods, including dried plasma spot sampling, as described in 5.
Other Lab Tests
Other lab tests, such as complete blood counts, may also be necessary to monitor for potential adverse effects, including bone marrow suppression.
Treatment and Dosing Considerations
Valproate dosing should be individualized, and the medication should be administered at a dose that maintains plasma concentrations within the therapeutic range. As noted in 6, careful attention must be applied to specific gender and age groups on an individual basis when interpreting plasma concentration results.
Caveats and Differentials
It is essential to consider the potential for drug interactions and individual variability in plasma concentrations when monitoring valproate therapy. Additionally, clinical symptoms, rather than laboratory findings alone, may be the most relevant indicators of impending complications, as noted in 3.
Conclusion
In conclusion, lab tests, including liver function tests and TDM, are essential for monitoring valproate therapy. By individualizing dosing and carefully monitoring plasma concentrations, healthcare providers can minimize the risk of adverse effects and ensure the effectiveness of valproate therapy, as supported by findings from 2, 3, 4, 5, 6.