Development of a method to quantify total and free irinotecan and 7-ethyl-10-hydroxycamptothecin(SN-38) for pharmacokinetic and bio-distribution studies after administration of irinotecan liposomal formulation

In 2015,liposomal formulation of irinotecan(ONIVYDE)has been approved by FDA and widely applied in the treatment of pancreatic cancer.ONIVYDE is a novel liposome formulation,entrapping CPT-11 in the aqueous core of vesicles using a modified gradient loading method.Due to toxicity concerns,it is essential to explore a rapid and reliable method to effectively isolate and quantify the non-liposomal,namely,free CPT-11and total CPT-11 in plasma.This study focuses on separation of non-liposomal CPT-11,evaluation of the pharmacokinetics of free CPT-11 and total CPT-11 and bio-distribution after intravenous administration of CPT-11 liposome.Free CPT-11 in plasma was separated by solid-phase extraction(SPE).The amount of total CPT-11 and main metabolite 7-ethyl-10-hydroxycamptothecin(SN-38)in plasma was quantified by ultra-performance liquid chromatography–MS/MS.The calibration curves fitted well and lower limit of quantitation for SN-38,free CPT-11,total CPT-11 and CPT-11 in tissue and were 5 ng/ml,10 ng/ml,4.44 ng/ml and 25 ng/ml respectively.The recoveries,precision and accuracy of the method appear satisfactory.Using this method,the pharmacokinetics and bio-distribution of CPT-11 liposome formulation after an intravenous dose of 2.5 mg/kg were then investigated.

Bio-distributions of [^(125)I]Spiro-I liposomes in mice

We investigated the bio-distributions of [125 I]Spiro-I formulated in sterically stabilized liposomes （SSL） or targeted liposomes （SSTL） in mice,especially their brain uptake.The [125 I]Spiro-I liposomes were prepared by film-ultrasound dispersion method.Cereport （RMP-7） was covalently conjugated with DSPE-PEG,which was attached to the surface of SSL to form SSTL.The encapsulation efficiencies （ee%） of [125 I]Spiro-I-SSL and [125 I]Spiro-I-SSTL were 97.47%±4.01% and 93.02%±2.98%,respectively.The average particle sizes were （66.47±0.76） nm and （71.40±0.45） nm,respectively.After intravenous administration,[125 I]Spiro-I was quickly eliminated from blood.SSL could prolong the retention time of [125 I]Spiro-I in blood and SSTL improved its brain uptake.The AUC of [125 I]Spiro-I-SSTL in brain was increased by 1.52 times as compared to [125 I]Spiro-I,indicating that SSTL could be used for the formulation of [125 I]Spiro-I for the imaging of central nervous system （CNS）.

Toxicity and bio-distribution of carbon dots after single inhalation exposure in vivo

Because of the advantages of excellent light stability, carbon dots（CDs） are considered to be a promising agent in the bio-marker application. Nevertheless, there are many unresolved issues with the toxicity of CDs in vitro and in vivo. In the study, CDs were synthesized by citric acid and ethylenediamine into deionized water, then the inhalation toxicity and bio-distribution of CDs in vivo were systematically assessed. The results showed that CDs caused animals death at higher dosages and induced injury in the lung and liver including inflammation and necrosis after single inhalation exposure at 5, 2 and 1 mg/kg dosages of the CDs. We also found that the injury increase with a dose-dependent and time-dependent manner. Fluorescent examination and TEM results showed that CDs mainly located at the lung and liver.And the fluorescent intensity increase with a time-dependent manner. This study provides a theoretical basis of the respiratory toxicity of CDs, and provides a basis for the use of CDs as a bio-marker.

The bio-distribution,clearance pathways,and toxicity mechanisms of ambient ultrafine particles

Ambient particles severely threaten human health worldwide.Compared to larger particles,ultrafine particles(UFPs)are highly concentrated in ambient environments,have a larger specific surface area,and are retained for a longer time in the lung.Recent studies have found that they can be transported into various extra-pulmonary organs by crossing the air-blood barrier(ABB).Therefore,to understand the adverse effects of UFPs,it is crucial to thoroughly investigate their bio-distribution and clearance pathways in vivo after inhalation,as well as their toxicological mechanisms.This review highlights emerging evidence on the bio-distribution of UFPs in pulmonary and extra-pulmonary organs.It explores how UFPs penetrate the ABB,the blood-brain barrier(BBB),and the placental barrier(PB)and subsequently undergo clearance by the liver,kidney,or intestine.In addition,the potential underlying toxicological mechanisms of UFPs are summarized,providing fundamental insights into how UFPs induce adverse health effects.

Effect of Kupffer cells depletion on ABC phenomenon induced by Kupffer cells-targeted liposomes

Accelerated blood clearance(ABC) phenomenon is common in many PEGylated nanocarriers, whose mechanism has not been completely elucidated yet. In this study, the correlation between Kupffer cells(KCs) and ABC phenomenon has been studied by KCs-targeted liposomes inducing ABC phenomenon and KCs depletion. In other words, the 4-aminophenyl-α-D-mannopyranoside(APM) lipid derivative DSPE-PEG 2000-APM(DPM), and 4-aminophenyl-β-L-fucopyranoside(APF) lipid derivative DSPE-PEG 2000-APF(DPF) were conjugated and modified on alendronate sodium(AD) liposomes to specifically target and deplete KCs. The dualligand modified PEGylated liposomes(MFPL) showed stronger ability to damage KCs in vitro and in vivo, which also could indirectly illustrate that dual-ligand modification could better target KCs. Besides, the hepatic biodistribution and pharmacokinetics could directly prove that MFPL had a stronger targeting ability to KCs. In addition, in depletion rats, plasma concentration and splenic biodistribution of MFPL and PEGylated liposomes(PL) were significantly elevated and hepatic biodistribution was significantly reduced, which demonstrated that KCs played an important role on elimination of nanoparticles. What’s more, ABC phenomenon of the secondary injection of PL was stronger in KCs depletion rats than that in normal rats, which indicated that depletion of KCs prolonged the circulation of PL in the first injection repeatedly stimulating B-cells in the marginal region of the spleen and causing it to secrete more IgM antibodies. This could also illustrate that anti-PEG IgM takes up a major station compared with KCs. Most important of all, KCs-targeted liposomes could induce a stronger ABC phenomenon than PL in normal rats, which declared that based on the same IgM concentration, the more the KCs were stimulated, the stronger ABC phenomenon was induced. However, in depletion rats, this difference of ABC phenomenon between PL and MFPL could no more exist, further demonstrating that KCs could participate and play a certain role in the ABC phenomenon.