Pharmacokinetic Study Of Lipid Nanoparticle Carrier Material SM-102 In Rats

COVID-19 is raging covertly and rapidly all around the world.As the number of patients increases over time.COVID-19 is extremely contagious,and the sequelae produced are permanent.As of March 24,2022,it has infected more than 470 million people worldwide and caused more than 6.1 million death.Vaccination can not only greatly reduce the risk of severe illness and death,but also help to establish a herd immunity barrier,and fundamentally control the epidemic and spread of COVID-19.Among the current COVID-19 vaccines,a variety of Messenger ribonucleic acid（m RNA）vaccines based on lipid nanoparticles（LNP）have been widely used.One of the most effective and protective m RNA vaccines is Spikevax^?from Moderna.Due to the urgency of the COVID-19 epidemic situation and the large demand for an effective vaccine,Spikevax^?took less than 2 years from clinical trials to approval for use,which was apparently much shorter than the decade or more that vaccine development needed before.Therefore,even though the vaccine has an advantageous preventive effect,it still has many unknown safety problems.It is reported that after intramuscular injection of Spikevax?,the body will experience local pain,fever,inflammation,myocarditis or various side effects,which is closely related to the very short development of the vaccine,the incomplete preclinical and clinical trials and the Ionizable lipid in LNP carrier firstly used in humans.Researchers have demonstrated that ionizable lipids in LNP are the direct reason of inflammatory responses at the injection site.That is why we chose the ionizable lipid SM-102,as the critical ingredient in the delivery of Spikevax^?LNP,to be the object of our study.After SM-102 is administered by intramuscular injection into the body,we use liquid chromatography tandem mass spectrometry（LC-MS/MS）to quantitative analysis the pharmacokinetic behavior of SM-102 in vivo.The following results shows the detail information of this study:（1）Development of quantitative analysis method of SM-102 in rat plasmaWe developed a quantitative LC-MS/MS method for the detection of SM-102 in rat plasma.After electrospray ion source ionization,the SM-102（m/z 710.8→300.1）was quantitatively analyzed by 6500+triple quadrupole mass spectrometry under the positive ion channel,using multiple reaction monitoring mode（MRM）.And according to the ICH harmonized guideline-biological sample analysis method validation M10,a number of methodological validations were carried out.It is confirmed that the method is stable and reliable,and could be applied to quantitatively analysis the SM-102 in rat plasma samples.（2）Pharmacokinetic study of SM-102 in plasmaIn this section,we use this method to study the pharmacokinetic behavior of SM-102 in rat plasma.The results showed that after intramuscular injection of 48μg SM-102 to SD rats,SM-102 was slowly eliminated in the blood circulation of rats,and the t_1/2 was 15.7±10.1 h,the C_max was 0.285±0.193μg/L,the area under the plasma concentration-time curve AUC_（0-t）was 8.94±4.71μg/L·h,AUC_（0-∞）was 10.1±5.47μg/L·h,the plasma clearance rate CL was 5.76±2.38 L/h,the V_d was 115±62.3 L.Generally,the whole body fluid of a 200 g rat is about 0.133 L,and the Vd in this study is more than 800 times that of the rat body fluid,much larger than the total volume of the rat body fluid.This suggests that only a small amount of SM-102 is absorbed into the blood circulation through the injection site after intramuscular injection,and most of it may exist in tissues.Moreover,the SM-102 basically eliminated in the blood circulation after 72 hours of administration.（3）Distribution of SM-102 in various organizationsThe quantitative analysis method of SM-102 in rat tissue samples was developed and verified by LC-MS/MS.Then,we use this method to study the distribution of SM-102 in rat liver,spleen and muscle of injection site.The results showed that 5 days after intramuscular injection of 48μg SM-102 in SD rats,the concentration of SM-102 in the liver and spleen was lower than the lower limit of quantification,but there was still11.0±15.4 ng/g of SM in the muscle of the injection site.The presence of SM-102suggests that SM-102 is more likely to store in the injection site muscle than in the liver and spleen.（4）Excretion study of SM-102The quantitative analysis method of SM-102 in rat urine and feces samples was established and verified by LC-MS/MS.Then,we use this method to detect the SM-102 in rat urine and feces.The results showed that,intramuscular injection of 48μg SM-102 to SD rats,within 0～120 h,SM-102 was not excreted in urine,and the cumulative excretion rate of SM-102 in feces was 0.288±0.0864%.In conclusion,this study took SM-102 in Spikevax^?as the research object,and clarified for the first time the pharmacokinetics of single component SM-102 in rat plasma after intramuscular injection,such as exposure,tissue distribution and excretion.process,which will provide reliable pharmacokinetic data support for the design and optimization of novel LNP carriers based on SM-102.