Why do you champion extended-release lithium over immediate-release lithium?
PL doesn’t “champion” any formulation of lithium. The most important thing to know about lithium is that it should be dosed only once daily, not multiple times daily. Its half life is about 24 hours and there is no reason to dose it more than once a day. Long-term outcome studies show that multiple daily dosing is a major predictor of long-term chronic kidney impairment. This issue is much much more important than whether immediate or extended release dosing is used. PL recommends that readers use whichever formulation they prefer, as long as they give them once daily only.
The extended release formulation cuts off the initial peak of dosing. In the standard formulation, this initial peak might cause more short-term side effects and/or brief exposure of the kidney to high lithium levels. PL doesn’t feel strongly about this point, which is conceptual, and not proven in empirical studies. If you feel strongly about using immediate-release lithium for other reasons, such as cost, that’s fine. The more important matter is to dose it once daily rather than multiple times daily.