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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of cancer research and clinical oncology 122 (1996), S. 723-726 
    ISSN: 1432-1335
    Keywords: Lipophilic cytosine arabinoside derivatives ; Liposomes ; Oral therapy ; L1210 leukemia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract TheN 4-alkylcytosine arabinoside derivativeN 4-octadecyl-AraC (AraC-Ocd, NOAC) and the (1-octadecylglycero-3-phospho)-AraC (Ocd-GroP-AraC, OPA) conjugate are new lipophilic derivatives of the cytostatic drug 1-β-d-arabinofuranosylcytosine (AraC) that produce high antileukemic effects in the L1210 murine leukemia model when administered orally or parenterally as liposomal formulations. Between 83% and 100% of the treated animals were cured after five consecutive daily oral drug applications with a total dose of 1 mmol/kg AraC-Ocd or Ocd-GroP-AraC. Corresponding results were obtained after parenteral therapy on days 2 and 6 after tumor inoculation with five- to ten-fold lower concentrations of these two compounds. A comparable cytotoxic activity was found with the orally active AraC-5′-(n-stearyl phosphate). However, because of its strong hemolytic toxicity this derivative cannot be used for parenteral therapy. Another AraC conjugate, which was modified with two long-chain hydrocarbons, the (1-octadecylglycero-3-phospho)-N 4-hexadecyl-AraC was, probably because of poor oral bioavailability, only active when applied parenterally. The new lipophilic AraC derivatives AraC-Ocd and Ocd-GroP-AraC are compounds with a high potential for the oral treatment of leukemias and possibly also of solid tumors.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1335
    Keywords: Lipophilic AraC derivatives ; Oral activity ; Toxicity ; Pharmacokinetics ; Liposomes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The oral cytostatic activity in L1210 mouse leukaemia of the two newN 4-alkyl derivatives of 1-β-d-arabinofuranosylcytosine (AraC),N 4-hexadecyl- andN 4-octadecyl-1-β-d-arabinofuranosylcytosine (NH- AraC, NO-AraC) was investigated. In contrast to AraC, both derivatives were highly cytostatic after oral application as liposome formulations. With treatment schedules of five consecutive dosages or with two applications on days 1 and 4 after intravenous tumour cell inoculation with a total dose of 470–1000 mg/kg NH- AraC or NO-AraC, 70%–100% of the treated animals were cured. The lethal dose in healthy ICR mice after a single intraperitoneal application, corresponding to the LD50, was 524 mg/kg for NO-AraC, whereas NH- AraC proved to be less toxic. The haematological toxicity. remained moderate for both drugs with a mild leucopenia and a drop in platelet counts, which recovered 4–6 days after treatment. The erythrocytes were not affected and haemolytic toxicities were absent. As non-haematological toxicities, at high drug concentrations, a pronounced atrophy of the rapidly dividing epithelia of the small intestines and of the white pulp of the spleen were observed. The blood levels of NH-AraC given orally reached values comparable to those after parenteral application of a four-times lower dose of NH-AraC, suggesting a moderate bioavailability. Thus, these two lipophilic derivatives of AraC are compounds with a potential for the oral treatment of malignant diseases.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1612-1112
    Keywords: Liposomes ; Biotin-avidin-coupling ; Biotinylated antibody ; Drug targeting
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The cytostatic effect of the widely used antitumor drug 1-β-D-arabinofuranosyl cytosine (ara C) can be improved by its chemical derivatization to lipophilic prodrugs. We have incorporated these prodrugs together with lipophilic biotin derivatives into membranes of unilamellar liposomes. Monoclonal antibodies were coupled to the biotin residues of the liposomes via avidin-biotin complexation resulting in prodrug-liposome-antibody complexes whichin vitro preferably bind to cells selectively recognized by the immobilized antibodies. The results open a promising way of drug targeting. The components and liposomal derivatives used for the stepwise preparation of the prodrug-liposome antibody complex are purified by means of preparative liquid chromatography. Lipophilic membrane components are chromatographed on silica gel, antibodies on hydroxylapatite and liposomal derivatives on Ultrogel AcA 22 columns. Concentration and desalting are achieved by ultrafiltration. The purification process can be quantitatively pursued by labelling with radioactive components.
    Type of Medium: Electronic Resource
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