ABSTRACT
Polymer nanomaterials have been attracted more and more attention because of their advantages such as long circulation, reduced immunogenicity and less side effects, and have become a hot research topic in nanomaterials. However, the number of polymer nanomedicines successfully applied in clinical application is very limited, and the unsatisfactory pharmacokinetic behavior is one of the main reasons for thisresult. After polymer nanoparticles enter the body, they will release free drugs and polymer excipients. Polymer nanoparticles are the loaded drugs and free drugs are the active chemicals for efficacy, while polymer excipients may cause excipient drug interactions. Therefore, the focus of the pharmacokinetics study of polymer nanoparticles should not be only limited to the free drugs themselves, but should also focus on the loaded drugs, free drugs and polymer excipients. The dynamic changes of polymer excipients and their metabolites pose new requirements and challenges for the bioanalysis of polymer nanomedicines. The characteristics and application scope of common analytical methods for detection polymer nanomedicines including chromatographic assay will be discussed in this paper. Moreover, this review will also summarize the absorption, distribution, metabolism and excretion of polymer nanomedicines. We hope this review will provide reference for the pharmacokinetics study, safety and effectiveness evaluation of polymer nanomedicines.
ABSTRACT
Liposome nanomedicine is a new drug preparation with nano scale, which is encapsulated by lipid bilayer vesicle structure. As a drug delivery carrier, liposome has many advantages such as good biocompatibility, biodegradation in vivo and strong targeting. The application of liposome nano drug delivery system can improve the pharmacokinetic behavior and efficacy of some drugs in vivo to a certain extent, and reduce toxic and side effects. After liposome nanomedicine enter into the body, free drugs will be released, so there will be loaded drugs and free drugs in the body. Loaded drugs are drug repositories, free drugs are related to their efficacy and adverse reactions. Therefore, the pharmacokinetics study of liposomes should focus on both loaded drugs and free drugs. Quantitative analysis of free drugs, liposome particles and their materials is a big challenge. The bioanalysis and pharmacokinetics of liposome nanomedicines will be introduced and discussed in this review. We hope this review will provide a reference for the development of liposome nanomedicine.
ABSTRACT
The fragmentation pathways of five estrogens (estradiol, estrone, equilin sulfate, 17 a-dihydroequilin sulfate and equilenin sulfate) have been studied with high resolution and high mass accuracy using electrospray ionization quadrupole time-of-flight mass spectrometry (ESI-Q-TOF/MS) in the negative ion mode. Molecular weights were obtained from [M-H](-) ions in the product ion spectra. The results indicate that the five structurally similar estrogens have similar fragmentation pathways. Using their stable isotope forms as internal reference compounds, the accurate mass and composition of the fragment ions were determined. During collision-induced dissociation (CID), cleavage is initiated by loss of oxygen atoms from carbon-17, after which D and C rings cleave sequentially and rearrange to finally form stable conjugate structures with highly abundant characteristic fragment ions at m/z 183 (accompanied by m/z 181), m/z 169 and m/z 145 (accompanied by m/z 143). Understanding these characteristic fragmentation pathways of estrogens will be helpful in identifying the structures of steroid hormones in general.