A review on phospholipids and their main applications in drug delivery systems

Phospholipids have the characteristics of excellent biocompatibility and a especial amphiphilicity.These unique properties make phospholipids most appropriate to be employed as important pharmaceutical excipients and they have a very wide range of applications in drug delivery systems.The aim of this review is to summarize phospholipids and some of their related applications in drug delivery systems,and highlight the relationship between the properties and applications,and the effect of the species of phospholipids on the efficiency of drug delivery.We refer to some relevant literatures,starting from the structures,main sources and properties of phospholipids to introduce their applications in drug delivery systems.The present article focuses on introducing five types of carriers based on phospholipids,including liposomes,intravenous lipid emulsions,micelles,drug-phospholipids complexes and cochleates.

Effects of complement inhibition on the ABC phenomenon in rats

Researchers reported that intravenously injected PEGylated colloidal drug carriers lose their long-circulating characteristic and accumulated extensively in liver when they are administrated twice in the same animal with certain intervals. This phenomenon was referred to as the 'accelerated blood clearance(ABC) phenomenon'. Some former studies had found that complement-mediated phagocytosis, activated by antigen–antibody complex, was responsible for inducing the phenomenon. According to the theory, we have used cobra venom factor to deplete complement in vivo and to investigate the effect of complement inhibition on the ABC phenomenon. Rats were administered by injection of cobra venom factor solution to build up the model of complement exhaustion/inhibition, and the effect of the inhibition of complement on ABC phenomenon was carried out. It seemed that inhibition of complement didn’t affect the pharmacokinetic of the first infection. By contrast, in rats of which complement had been depleted, the second dose of PEGylated nanoemulsions showed enhanced circulation time compared with normal rats in a complement inhibition-independent manner, but the ABC phenomenon was not completely eliminated. It indicated that complement inhibition could certainly weaken the accelerated clearance;meanwhile, there were other factors causing the ABC effect.These findings provide novel insights into the attenuating of ABC phenomenon and lay foundation for further study of immune mechanism.

Mixed PEGylated surfactant modifying system decrease the accelerated blood clearance phenomenon of nanoemulsions in rats

The accelerated blood clearance(ABC) phenomenon which is induced by repeated injection of poly(ethylene glycol)(PEG)-coated colloidal carriers gives clinical challenge to the promising drug delivery system. It is necessary to decrease this unexpected immunological response.A novel 4-arm poly(ethylene glycol-5000)4-cholesteryl methyl amide(4-arm PEG5000-CHMA)has been synthesized. The structure of 4-arm PEG5000-CHMA was confirmed by IR and 1H-NMR spectrum. The pharmacokinetics of the tocopheryl nicotinate(TN)-loaded nanoemulsions modified with 4-arm PEG5000-CHMA or/and 1, 2-distearoyl-Sn-glycero-3-phosphoethanolamine-n-[methoxy(poly-ethyleneglycol)-2000](mPEG2000-DSPE) have been studied. Furthermore, the ABC phenomenon has been detailed investigated in rats by TN-loaded nanoemulsions modified with 4-arm PEG5000-CHMA and mPEG2000-DSPE(CPNE). The plasma levels of TN and anti-PEG IgM antibody were determined by HPLC and ELISA, respectively.The circulation time of the CPNEs were comparable to the mPEG2000-DSPE coated nanoemulsions. Moreover, the ABC phenomenon can be decreased by CPNEs. This study designs a method to decrease the ABC phenomenon and develops a clinical promising nanoemulsion for therapeutic or imaging purpose.

Primary nasopharyngeal carcinoma with cerebrospinal fluid EBV positivity:A case report and mini literature review

Background:To summarize the diagnosis and treatment of a patient with nasopharyngeal carcinoma and cere-brospinal fluid(CSF)Epstein-Barr virus(EBV)positivity(determined by next-generation sequencing),review the relevant literature,and explore the significance of EBV presence in the CSF of patients with nasopharyngeal carcinoma.Methods:A patient presenting with headache as the initial symptom was diagnosed with nasopharyngeal carci-noma and admitted to the Eighth Medical Center of Chinese PLA General Hospital on March 3,2021.Available databases were screened for reports on nasopharyngeal carcinoma with EBV-positive CSF and analyzed.The patients’general information,initial symptoms,treatment,and prognosis were subsequently evaluated.Results:EBV-positive CSF is commonly observed in patients with recurrent nasopharyngeal carcinoma.However,no reports of EBV-positive CSF in patients with primary nasopharyngeal carcinoma have been published to date.Conclusion:The presence of EBV in the CSF of patients with recurrent nasopharyngeal carcinoma is indicative of a poor prognosis.Thus,newly diagnosed nasopharyngeal carcinoma patients should undergo a lumbar puncture as soon as possible to have their CSF tested for EBV.Such a measure would promptly predict the prognosis and facilitate the development of a personalized treatment strategy.