Nonclinical Pharmacokinetic Study Of Cationic Lipid ALC-0315 In Lipid Nanoparticle

Since December 2019,the novel corona virus pandemic has spread violently around the world,humanity has been hit by the most widespread global pandemic in a century.As an effective means of preventing epidemic situation,vaccines are the scientific solution to contain the epidemic at its root.Currently,there are two kinds of mRNA COVID-19 vaccine that use lipid nanoparticle(LNP)as delivery vector on the market: The mRNA-1273 vaccine developed by Moderna and the Comirnaty vaccine jointly developed by Pfizer and BioNTech.Both received emergency authorization from the FDA and were quickly put into mass production and employment.Although mRNA vaccine has remarkable effect and developed rapidly,mRNA is easy to degrade in the body and difficult to cross cell membranes,which has become the bottleneck of its development.According to the above characteristics of mRNA vaccine,LNP was constructed to compensate for the functional deficiency of mRNA.Cationic lipids in LNP can condense negatively charged nucleic acid into small particles through charge interaction,combine with negatively charged cell membrane,induce relevant nucleic acid to be absorbed into cells,and play an irreplaceable role in targeted delivery of mRNA.However,several studies have shown that cationic lipids may cause toxic effects in vitro or in vivo,such as: cationic lipids may lead to cell contraction,reduced mitotic number,cytoplasmic vacuoles;polyvalent cationic lipids can cause lung toxicity;the interaction between cationic lipids and macrophages may lead to apoptosis.At the same time,some serious adverse events,such as acute myocarditis and thrombocytopenia,were reported with the widespread and mass vaccination of the mRNA vaccine Comirnaty.It is not clear whether the occurrence of these adverse events is related to the cationic lipid in Comirnaty vaccine,and there have been no pharmacokinetic studies of the cationic lipid material ALC-0315 in this vaccine to date.In this study,cationic lipid ALC-0315 in Comirnaty vaccine was used as research object,and LC-MS/MS detection method was established in various substrates of rats to evaluate the pharmacokinetic behavior of ALC-0315 in rats,and to reveal the change process of ALC-0315 in vivo.Plasma pharmacokinetics of ALC-0315 in rats showed that after 200 μg/kg ALC-0315 was intramuscular injected into rats,the elimination efficiency of ALC-0315 in rat plasma was relatively slow,and the elimination in plasma was relatively complete after 96 h.The Vd value was lower than the total volume of plasma and body fluid of rats,indicating that ALC-0315 was less distributed in plasma and extracellular fluid.The results of tissue distribution of ALC-0315 in rats showed that 5 days after intramuscular injection of 200 μg/kg ALC-0315,the exposure level in liver and spleen was low,but the exposure level in the muscle of injection site was relatively high.Indicating that ALC-0315 has a certain accumulation at the injection site.This suggests that we need to be concerned about possible muscular toxicity.The results of rat excretion study of ALC-0315 showed that the cumulative excretion rate of ALC-0315 primary form in urine and feces was low.Since there are two ester bonds in the structure of ALC-0315,it is easy to be hydrolyzed by esterase after entering the body,so it is speculated that most of ALC-0315 may be excreted in the form of metabolites.