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Paediatric Laboratory Medicine

Ethosuximide

Clinical Significance

Ethosuximide is the principle succinimide derivative shown to be effective in the treatment of absence (petit mal) epilepsy. It is considered the treatment of choice for this condition, which occurs primarily in childhood. At therapeutic levels, the frequency of convulsions is apparently reduced by depression of the motor cortex and elevation of the threshold of the central nervous system stimuli. Due to individual pharmacokinetics and changes in patient metabolism, plasma ethosuximide levels may be unpredictable. At toxic levels, ethosuximide may produce side effects to the gastrointestinal, central nervous and hematopoetic systems.

Test Name

Ethosuximide

Alternate Name/ Synonym

Zarontin

Test Code

ETHOS

Drug Class

Anticonvulsants

Division

Therapeutic Drug Monitoring - TDM

Method

HPLC

External Proficiency Testing

CAP

Turn Around Time

Daily @ 14:00h

Disease/Condition

Anticonvulsant

Specimen Type

Serum, Plasma (Heparin or Citrate)

Minimum Specimen Requirements

50 uL

Optimal Collection Time

Trough: 0-30 minutes prior to dose

Storage/Transportation

4°C (transport with a cool pack if possible)

Approval is not required

CPT Codes

80168

Shipping and Contact Information

The Hospital for Sick Children
Rapid Response Laboratory
170 Elizabeth Street, Room 3642
Toronto, ON
M5G 2G3
Canada
Phone: 416-813-7200
Phone: 1-855-381-3212

Therapeutic Range

280-710 umol/L

Critical Values

> 1060 umol/L