Pharmacokinetics and tissue distribution of two novel isomerism anticancer platinum compounds

Pharmacokinetics and tissue distribution in rats of a novel anticancer platinum compound LLC-1903

LLC-1903, a novel anticancer compound, was synthesized by optimizing the structure, which was derived from altering the leaving group of lobaplatin. It has an excellent in vitro anti-cancer activity, high water solubility, high stability in solution and low in vivo toxicity according to our former study.The plasma pharmacokinetics (PK) and tissue distribution of LLC-1903 and lobaplatin in rats were determined after intravenous administration of a single dose (0.06 mmol/kg body weight). Inductively coupled plasma mass spectrometry (ICP-MS) was used to measure the concentration of platinum (Pt) in plasma and tissue samples.Most PK parameters of the Pt in LLC-1903 showed a significant difference from those of lobaplatin. The plasma level of LLC-1903 is only half of that of lobaplatin (p < 0.01) which could be the direct result of faster drug clearance. The tissue distribution showed that both LLC-1903 and lobaplatin were mainly found in the liver and kidney, and less in other organs. At four time points (0.083, 0.5, 1 and 4 h) after administration, the tissue concentrations of LLC-1903 were almost always significantly higher than those of lobaplatin (p < 0.05 or p < 0.01).

Anticancer activity and tissue distribution of platinum (II) complex with lignin-derived polymer of benzene-poly-carboxylic acids

Platinum-containing antineoplastic agents with physiologically active ligands seem to be a promising direction in anticancer drug design. PDBA is a novel promising antineoplastic agent, containing polymer ligand of natural origin (international patent WO2013/143549 A1). Polymer ligand of PDBA has a highly functionalised polyphenolic backbone, which exerts its own pharmacological effect via immune modulation and regulation of gene expression. PDBA is a cis-diammineplatinum(II) complex, containing mono-deprotonated benzene-poly-carboxylic acids, derived from lignin, and hydroxyl group as O-donor ligands (approximate bulk formula C₈₃H₇₀N₂O₂₇Pt). The agent is being evaluated in Phase II controlled clinical trials in metastatic breast cancer patients. In the present study, tissue distribution and tumour growth inhibition effects of PDBA, cisplatin and carboplatin were compared in SHR female mice, bearing inoculated solid Ehrlich carcinoma. The agents were administered subcutaneously every second day for the period of 10days (5 injections) at 62.5mg/kg, 3.0mg/kg and 18.5mg/kg for PDBA, cisplatin and carboplatin, respectively. Experimental animals were sacrificed on the Days 11, 16 and 23 after the inoculation of the tumour. The doses of all studied drugs were selected to obtain similar antitumour efficacy with ca. 50% growth inhibition of the Ehrlich tumour at the end of the study. The efficacy of a single platinum reactive moiety [cis-diammineplatinum(II)] was shown to be the highest for cisplatin, followed by PDBA and finally carboplatin. However, the toxicity of PDBA was considerably lower than that of carboplatin and especially cisplatin. The drugs were mainly distributed in lungs, kidneys, liver, spleen and tumour tissue. PDBA showed quite high accumulation in the tumour tissue, possibly, owing to the effect of the lignin-derived ligand.

Preparation and in vivo safety evaluations of antileukemic homoharringtonine-loaded PEGylated liposomes

In order to improve the in vivo safety and specific delivery efficiency of the antileukemic homoharringtonine (HHT) at the targets, the long-circulating PEGylated liposomes loaded with HHT (LCLipo-HHT) were prepared. Their physical characteristics, in vitro drug release, in vivo pharmacokinetic properties and elementary toxicity were evaluated. The mean diameter of the prepared LCLipo-HHT is 75.6 ± 3.2 nm and the zeta potential is -16.9 ± 2.5 mV. The entrapment efficiency of HHT in the liposomes is 69.5 ± 1.7%. In pharmacokinetic experiments, an increased plasma concentration as well as blood circulation time was obtained when distearoyl phosphoethanolamine-PEG 2000 lipid was added in the formulation, which results in enhancing drug delivery efficiency. Hemolysis test, vascular irritation test and acute toxicity test were used to demonstrate toxicity of LCLipo-HHT. Compared with clinical HHT injection dosage, LCLipo-HHT indicated no vascular irritation, good hemocompatibility, as well as much better safety. Therefore, the prepared LCLipo-HHT can be used as a promising anticancer formulation for antileukemic therapy in the future.