Received on May 21, 2008
Accepted on October 28, 2008

Drug Monitoring and Toxicology

Clinical Utility of an LC-MS/MS Seizure Panel for Common Drugs Involved in Drug-Induced Seizures

¹ Department of Laboratory Medicine, University of California–San Francisco, San Francisco, CA
² Department of Laboratory Medicine, University of California–San Francisco, San Francisco, CA, and Clinical Laboratory, San Francisco General Hospital, San Francisco, CA
³ Clinical Pharmacy, University of California–San Francisco, San Francisco, CA, and California Poison Control System, San Francisco Division, San Francisco, CA
⁴ Emergency Medicine, University of California–San Francisco, San Francisco, CA

^* To whom correspondence should be addressed. E-mail: wualan{at}labmed2.ucsf.edu.

BACKGROUND: Approximately 6% of new-onset seizures are drug-related, but there is currently no reliable way to determine if a seizure is drug-induced. Liquid chromatography/tandem mass spectrometry (LC-MS/MS) is a powerful tool that allows simultaneous detection of numerous analytes of diverse chemical nature in patient samples. This allows a single analysis to incorporate many compounds relevant to a particular clinical presentation, such as suspected drug-induced seizures. We investigated whether results from a seizure panel using LC-MS/MS could affect patient care.

METHODS: We developed a semiquantitative LC-MS/MS assay to detect 12 chemically diverse drugs implicated in drug-related seizures. We collected leftover serum and plasma samples from patients who had seized, extracted the solid phase, and performed analysis using a hybrid triple quadrupole/linear ion trap mass spectrometer. After assembling a team of medical and toxicology experts, we developed and used a scoring system to determine whether the results of the seizure panel would have affected patient treatment in each case where a drug was detected.

RESULTS: In an analysis of 157 samples from patients who seized, 17 (11%) were found to be positive for a drug on the seizure panel. The team of experts determined that the test results probably or definitely would have affected treatment in 7 (41%) of these cases.

CONCLUSIONS: A test that detects the presence of drugs implicated in drug-induced seizures can help physicians determine if an unexplained seizure is drug-related and thus potentially better direct patient care. Additionally, LC-MS/MS is an effective tool for answering clinically driven questions.