Researchers report the successful development of a prototype lab-on-a-chip for measuring anti-epileptic drug levels from saliva samples. Initial results show the promise of the immunoassay for two commonly used anti-epileptic drugs, but the researchers say they hope to expand the noninvasive testing system to include validation of up to 15 marketed anti-epileptic drugs, potentially replacing the need for serial, outpatient serum monitoring in optimally dosing millions of patients with epilepsy. The researchers developed a multiplexed nanochip-based immunoassay that incorporated drug-specific sensitized beads for the anti-epileptics phenytoin and phenobarbital, according to the proof-of-concept study presented at the American Epilepsy Society annual meeting (Washington, D.C.; Dec. 6-10). Epilepsy patients taking one or both of the drugs were recruited to provide a single serum sample and multiple salivary samples (collected either by passive drool or an oral swab that was diluted). Saliva results were compared to gold-standard serum testing conducted using a particle-enhanced turbidimetric immunoassay in a clinical chemistry laboratory, as well as salivary samples assayed with gas chromatography-mass spectrometry at a commercial toxicology laboratory. Limits of detection and the useful range of the assay were computed. The bio-nanochip calibration signals were “robust” and provided low, reliable limits of detection. The assay also compared favorably to the gold-standard serum tests and gas chromatography-mass spectrometry testing. Future work will increase the number of samples tested, expand the assay to include additional drugs, and adapt the electronic reader to a practical point-of-care diagnostic size, eventually a handheld, credit card-sized device, that will make monitoring drug levels outside of medical settings feasible. “Labs add time, cost, inconvenience, and another problem is needlephobia and difficulties with vascular access, especially in small children,” Giridhar Kalamangalam, M.D., an associate professor of neurology at University of Texas, Houston, tells DTET. “These bio-nanochips are a new generation of compact, programmable chemical processors that will satisfy the urgent need for a noninvasive, adaptable, and cost-effective alternative to a blood test. They have already been successfully piloted in other contexts and their advantages of portability and easy accessibility with alternate fluid samples make adaptability to the epilepsy world sensible.” While it will likely take several years before the at-home monitoring system is commercially available, Kalamangalam says making the system as user friendly as possible is the goal and that includes not just the user interface, but the cost. The disposable chips will likely cost just cents to run a test and the researchers are trying to get the electronic reader to be similar in cost to a cellphone. Takeaway: Lab-on-a-chip test development will continue to expand the opportunity to utilize at-home monitoring for chronic conditions, including epilepsy.