Diazyme Receives 510(K) FDA Approval for Enzymatic Lithium Assay Kit

Diazyme Receives 510(K) FDA Approval for Enzymatic Lithium Assay Kit

SAN DIEGO, CA – December 23, 2003 - Diazyme Laboratories, a company that applies its proprietary Substrate Trapping-Enzyme Technology® (STE) platform to develop low cost and high quality diagnostic products for clinical and research uses, announced today that the U.S. Food and Drug Administration (FDA) has granted Diazyme 510(K) clearance to market their Enzymatic Lithium Assay Kit for the quantitative in vitro determination of lithium in human serum.

With Diazyme's Enzymatic Lithium Assay, serum lithium levels are determined spectrophotometrically through a kinetic coupling assay system involving a Diazyme's proprietary phosphatase whose activity is sensitive to lithium (IC50 = 0.1mM). Through enzymatic coupling, a quinone dye, which has maximal absorbance at 556nm, is formed. The rate of the quinone dye formation is inversely proportion to the concentration of lithium in serum samples. The assay has been fully automated with general chemistry analyzers such as Hitachi, Cobas Mira and Eurolab Analyzers.

For decades, lithium carbonate remains one of the most effective agents for the treatment of patients suffering from bipolar disorder (manic depressive psychosis). Recently, studies have shown that lithium holds promise against Alzheimer's disease. However lithium has many side effects and over dosage of lithium can cause acute Li+ intoxication, which occurs due to a narrow therapeutic index. Serum Li+ levels higher than 1.5mM (12 hours after a dose) usually indicates a significant risk of toxicity.

Currently, the commonly used methods to detect serum lithium are ion-selective electrode (ISE) and flame photometry. However, routine maintenance of these analyzers requires effort and can be cumbersome. Diazyme's lithium enzymatic assay is proven to be equivalent to currently available tests but is more convenient for use in automated analyzers.

Key Assay Characteristics: Diazyme's lithium enzymatic assay is a two reagent (R1 and R2) based kinetic assay system. The results are obtained in 10 minutes by measuring absorbance at 550nm. No off line pretreatment is needed. The assay has excellent accuracy and precision with a wide measuring range (0 to 3mmol/L).

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