Lipid Emulsion Dosing Regimens and the Influence of Beta-Blocker Lipid Solubility on Lipid Emulsion Resuscitation for...

I read with interest the systematic review by Meamar et al. on intravenous lipid emulsion (ILE) therapy for beta-blocker toxicity. I highlight two important issues that may further refine the interpretation of ILE efficacy. First, although no association was observed between ILE dose and cardiovascular outcomes, the optimal dosing regimen for nonlocal anesthetic drug toxicity remains uncertain because current practice is largely extrapolated from local anesthetic systemic toxicity despite important pharmacokinetic differences. Second, drug lipophilicity should be evaluated using the distribution coefficient (log D), rather than the octanol/water partition coefficient (log P), because log D reflects pH-dependent ionization under physiological conditions. As metabolic acidosis accompanying severe beta-blocker poisoning reduces log D, the lipid shuttle effect may diminish, potentially increasing the relative contribution of ILE's direct cardiotonic and metabolic effects. These considerations suggest that early ILE administration may be advantageous and that log D may better predict responsiveness to ILE than log P. Further studies are warranted to establish optimal dosing strategies and validate the clinical relevance of log D.