Synthesis And Antibacterial Activity Of Clarithromycin 2’-OH Ester

Clarithromycin is a semi-synthetic macrolide antibiotic developed by Japan’s Taisho Company,which acts on the 50 S subunit of the ribosome to prevent protein synthesis,thereby inhibiting the growth and reproduction of bacteria.The drug is widely used in clinical practice,but mainly in the form of gastrointestinal absorption.Because of its strong vascular irritation,its intravenous injection is selected when there is no other drug,and it is injected slowly during injection,and the patient is always observed for discomfort,which greatly limits the use of this drug.For patients with severe infections or patients who cannot be taken orally,injection is the best choice.Other antibiotic injections have been used for a long time,and most bacteria have developed resistance to a certain extent.The clarithromycin-resistant bacteria are relatively small,so the development of a safe and effective clarithromycin injection has very important application significance.In recent years,emulsions and liposomes have developed rapidly,and they are favored by many researchers because of their advantages of increasing drug stability,reducing adverse reactions,sustained release,and targeting.These two dosage forms encapsulate the drug in microcapsules composed of phospholipids,which can isolate the direct effect of the drug and the blood vessel wall and reduce the stimulation of the drug to the blood vessels.This feature can well compensate for the strong blood vessel stimulation of clarithromycin injection.shortcoming.However,clarithromycin is a BCS4 drug,and its fat solubility and water solubility are very small,so it is difficult to directly make the above dosage form.The existing research is either complicated and difficult,or the added excipients are expensive or difficult to use in large quantities.In this study,the idea of modifying the drug structure with flurbiprofen axetil and dexamethasone axetil to increase the lipid solubility was used to study the esterification of clarithromycin.Clarithromycin 2’-OH ester was synthesized by one-step method with acid chloride.Using butyryl chloride,octanoyl chloride,lauric acid chloride and palmitic acid chloride to react with clarithromycin can synthesize a series of esters in one step,but clarithromycin has two active hydroxyl groups and the molecular structure is complex,which leads to the inability to complete the reaction completely and the side effects of clarithromycin.production of products.Subsequent purification operations are many,and the final yield obtained after multiple washing and extraction with alkaline aqueous phase,column chromatography and recrystallization is about 60%,and the purity is greater than 98%.The compound was identified as the target ester compound by mass spectrometry,H NMR and C NMR.With reference to the HPLC method of clarithromycin,the analytical methodology of five esters by HPLC was established.The solubility of esters in phosphate buffer,LCT and MCT at different p H and the oil-water partition coefficient of different media were determined.The results show that the solubility in the water phase increases with the increase of p H,but the solubility in the water phase is only about 100μg/m L;while the solubility in the oil phase is greatly improved,and the solubility of CLAP in MCT reaches125mg/g.Esterates can be dissolved in the oil phase or phospholipid bilayer to prepare emulsions or liposomes.In vitro antibacterial activity of clarithromycin 2’-OH esters.The inhibitory activity of five esterifications against Staphylococcus aureus;Escherichia coli;Methicillin-resistant Staphylococcus aureus was investigated.The results showed that the antibacterial activity of the esterification was greatly reduced,and the antibacterial activity of the ester compound as a prodrug needed to kill bacteria at a high dose.Due to the presence of esterase in the body,the drug will be decomposed into clarithromycin or other active substances to play a role after entering the body,so the pharmacokinetics of the ester compound in the body needs to be further studied.Biosafety study of clarithromycin 2’-OH esters.Clarithromycin itself has a strong stimulatory effect on blood vessels,so it is also necessary to conduct relevant safety studies on ester compounds.In vitro hemolysis experiments,rabbit ear vein experiments and rabbit muscle irritation experiments were carried out.RESULTS: Ester compounds did damage to erythrocytes and certain damage to blood vessels.Among them,CLAP stimulated the least,CLABZ stimulated the most;CLABZ stimulated the muscle the most,and fatty acid esters did not stimulate much.A preliminary study on CLAP liposomes.CLAP was selected as a drug for liposome preparation because of its excellent lipid solubility and less irritation.The particle size distribution of the liposomes prepared by thin film dispersion was 172 nm,the PDI was 0.082,and the encapsulation efficiency was 88%.The particle size,PDI and encapsulation efficiency did not change much within 30 days,indicating good storage stability at 4°C.