B-335 Rapid Quantitative Clozapine Measurements at the Point-of-Care Using Capillary Blood

Abstract

Abstract Background Clozapine is the most effective medication for treatment-resistant schizophrenia, and is endorsed in professional guidelines. Therapeutic drug monitoring (TDM) is recommended for Clozapine due to high pharmacokinetic variability and risk of adverse drug reactions. The effectiveness of TDM for managing clozapine patients is limited by the lack of immediate results. Methods A novel immunoassay, the MyCare Insite Clozapine Test (MCI), was developed that uses 20 µL of capillary blood (CP) and delivers 7-minute quantitative results for a portable point-of-care (POC) device. To validate the MCI system, matching CP and serum samples were collected from 113 patients at two sites. CP was tested immediately with MCI and compared to serum immunoassay results on a Beckman-Coulter AU480 analyzer. Precision was evaluated using three whole blood spiked samples and two assay controls over five days with five replicates per day. Results The figure shows a correlation plot evaluated by Passing-Bablok regression of the POC MCI (y-axis) and the Beckman analyzer (x-axis). The regression line was y = 1.05*x + 1.4 ng/L, r = 0.927, indicating good agreement. Precision studies demonstrated that repeatability was ≤11% and within-lab precision was ≤13%. Conclusion Quantitative Clozapine results are available in 7 min using CP in a portable POC device. A rapid POC alternative can achieve timely patient results in many testing environments. Rapid Clozapine testing has the potential for expanding utilization of this important drug by providing actionable POC results.