Optimal timing for lithium levels

Reddy and Reddy (2014) discuss the optimal timing for lithium levels in patients taking once-daily extended-release formulations. They argue blood sampling 24 h after previous dose rather than standard 12 h. I interpret data quite differently. The authors start with assumption that clinician wants a trough level. disagree. What one is to be able compare patient’s level large body of published knowledge about dosing. Almost all comes from 12-h draws plain (immediate-release) carbonate or citrate. So, real question interest is, formulations, at what time point does draw most accurately carbonate? answer not obvious because formulations affect only absorption excretion lithium. Their primary benefit reducing transient peak serum concentration, delaying (already relatively slow) elimination lithium. Emami colleagues (2004) provide needed data. First they show 90% administered commercial formulation (Eskalith CR®) absorbed by 4 dose, ~100% 8 (their Figure 2A). Second, immediate extended release are essentially identical ns5:href="https://sites.ualberta.ca/~csps/JPPS7(3)/J.Emami/Figure%20(3).gif">Figure 3). Thus ideal drawing tablets.