Determination of vinca alkaloids in mouse tissues by high-performance liquid chromatography

The Alterations in the Expression and Function of P-Glycoprotein in Vitamin A-Deficient Rats as well as the Effect of Drug Disposition in Vivo

This study was aimed to investigate whether vitamin A deficiency could alter P-GP expression and function in tissues of rats and whether such effects affected the drug distribution in vivo of vitamin A-deficient rats. We induced vitamin A-deficient rats by giving them a vitamin A-free diet for 12 weeks. Then, Abcb1/P-GP expression was evaluated by qRT-PCR and Western blot. qRT-PCR analysis revealed that Abcb1a mRNA levels were increased in hippocampus and liver. In kidney, it only showed an upward trend. Abcb1b mRNA levels were increased in hippocampus, but decreased in cerebral cortex, liver and kidney. Western blot results were in good accordance with the alterations of Abcb1b mRNA levels. P-GP function was investigated through tissue distribution and body fluid excretion of rhodamine 123 (Rho123), and the results proclaimed that P-GP activities were also in good accordance with P-GP expression in cerebral cortex, liver and kidney. The change of drug distribution was also investigated through the tissue distribution of vincristine, and the results showed a significantly upward trend in all indicated tissues of vitamin A-deficient rats. In conclusion, vitamin A deficiency may alter Abcb1/P-GP expression and function in rat tissues, and the alterations may increase drug activity/toxicity through the increase of tissue accumulation.

Assay of CCNU in Tumor by RP-HPLC

This paper reports a RP-HPLC method for the determination of Lomustine (CCNU) in mouse tumor tissue. CCNU was separated and determined on a reverse-phase C18 5 microm column with a mobile phase of H2O-acetonitrile (54:46), detected at 254 nm and no internal standard. The calibration curve was linear (r = 0.9999) within the range of 0.98-15.68 microg/ml for CCNU. The recovery ratio of CCNU was 68.64% (n = 5). The relative standard deviation (RSD) was 0.32%. This method is simple and accurate.

Liposome drugs' loading efficiency: a working model based on loading conditions and drug's physicochemical properties

Remote loading of liposomes by transmembrane gradients is one of the best approaches for achieving the high enough drug level per liposome required for the liposomal drug to be therapeutically efficacious. This breakthrough, which enabled the approval and clinical use of nanoliposomal drugs such as Doxil, has not been paralleled by an in-depth understanding that allows predicting loading efficiency of drugs. Here we describe how applying data-mining algorithms on a data bank based on Barenholz's laboratory's 15 years of liposome research experience on remote loading of 9 different drugs enabled us to build a model that relates drug physicochemical properties and loading conditions to loading efficiency. This model enables choosing candidate molecules for remote loading and optimizing loading conditions according to logical considerations. The model should also help in designing pro-drugs suitable for remote loading. Our approach is expected to improve and accelerate development of liposomal formulations for clinical applications.

The controlled release study of Vincristine Sulfate

We prepared microspheres of Vincristine Sulfate (VCR) through drying-from-oil method, then mixed the microspheres into 0.7% collagen swelling solution to prepare emulsion, spread the emulsion on plate to form film by frozen-dry method. The film was cross-linked and sterilized, then planted into the site of tumor and expected to release at steady speed. We measured the release of VCR in vivo and in vitro by HPLC. The results demonstrated that VCR controlled release films release at approximate steady speed in 15 days.

Pharmacokinetics and antitumor effects of vincristine carried by microemulsions composed of PEG-lipid, oleic acid, vitamin E and cholesterol

In this study, injectable microemulsions of vincristine (M-VCR) were prepared and its pharmacokinetics, acute toxicity and antitumor effects were evaluated. In M-VCR, the surfactants were PEG-lipid and cholesterol, the oil phase was a vitamin E solution of oleic acid and VCR. The particle size distribution and zeta potential of M-VCR were measured by the laser light dynamic scattering method. The VCR-loading efficiency was measured by Sephadex G50 column chromatography. The stability of M-VCR was monitored by particle size, VCR-loading efficiency and VCR content changes of M-VCR stored at 7 degrees C. The pharmacokinetics, acute toxicity and antitumor effects of M-VCR were studied in C57BL/6 mice bearing mouse murine histocytoma M5076 tumors. When stored at 7 degrees C in the dark for 1 year, the average diameter and VCR-loading efficiency of M-VCR changed from 138.1+/-1.2 nm and 94.6+/-4.7% to 127.1+/-2.4 nm and 91.3+/-4.8% (n=3), respectively, while 7.4+/-0.3% VCR decomposition was observed (n=3). The plasma AUC of M-VCR was significantly greater than that of free VCR (F-VCR). The heart, spleen and liver AUC(0.08-12 h) of M-VCR were significantly smaller than those of F-VCR while the kidney AUC(0.08-12 h) of M-VCR was significantly greater than that of F-VCR. The tumor AUC(0.08-12 h) of M-VCR was significantly greater than that of F-VCR. M-VCR had lower acute toxicity and greater potential antitumor effects than F-VCR in M5076 tumor-bearing C57BL/6 mice. M-VCR is a useful tumor-targeting microemulsion drug delivery system.

Analytical approaches for traditional chinese medicines exhibiting antineoplastic activity

Traditional Chinese medicines have attracted great interest in recent researchers as alternative antineoplastic therapies. This review focuses on analytical approaches to various aspects of the antineoplastic ingredients of traditional Chinese medicines. Emphasis will be put on the processes of biological sample extraction, separation, clean-up steps and the detection. The problems of the extraction solvent selection and different types of column chromatography are also discussed. The instruments considered are gas chromatography, capillary electrophoresis (CE) and high-performance liquid chromatography (HPLC) connected with various detectors (ultraviolet, fluorescence, electrochemistry, mass, etc.). In addition, determinations of antineoplastic herbal ingredients, including camptothecin, taxol (paclitaxel), vinblastine. vincristine, podophyllotoxin, colchicine, and their related compounds, such as irinotecan, SN-38, topotecan, 9-aminocamptothecin, docetaxel (taxotere) and etoposide, are briefly summarized. These drugs are structurally based on the herbal ingredients, and some of them are in trials for clinical use. Evaluation of potential antineoplastic herbal ingredients, such as harringtonine, berberine, emodin, genistein, berbamine, daphnoretin, and irisquinone, are currently investigated in laboratories. Other folk medicines are excluded from this paper because their antineoplastic ingredients are unknown.

The toxicology of African herbal remedies

Toxicity related to traditional medicines is becoming more widely recognized as these remedies become popular in developed countries. Accidental herbal toxicity occurs not only as a result of a lack of pharmaceutic quality control in harvesting and preparation but also because herbal remedies are believed to be harmless. Although there is a huge amount of data available documenting the pharmacologically active ingredients of many plants, it is seldom helpful to the toxicologist in an acute situation. Current analytic methods such as high-performance liquid chromatography, gas chromatography--mass spectrometry, and immunoassays can provide identification of the toxin in those few cases in which the history or symptoms give a clear lead, but broad screening methods remain to be developed. In most cases of plant poisoning, treatment continues to be only of symptoms, with few specific antidotes available. It is important that toxicologists in the West be alert to the possibility of encountering poisoning in patients due to traditional African remedies.