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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Taxol is a complex diterpenoid natural product under investigation for therapy of colon, ovarian, lung, and breast cancer, as well as for melanoma and lymphoma. One problem associated with the administration of Taxol is its low solubility; the formulation used clinically contains polyethoxylated castor oil (Cremophor EL) and ethanol as excipients. Cremophor EL is implicated in hypersensitivity reactions observed on infusion of Taxol. To eliminate the Cremophor EL vehicle and possibly improve the antitumor efficacy of Taxol, a systematic approach was taken to formulate Taxol in phospholipid suspensions (liposomes). Prototype formulations were developed that have sufficient chemical and physical stability to test the hypothesis that liposomes can alter the pharmacology of Taxol, in addition to providing a biologically compatible carrier in which to administer the drug. In vitro. Taxol liposomes retain the growth-inhibitory activity of free Taxol against a variety of tumor cell lines. In vivo, preliminary results showed no effect of free Taxol (in Cremophor EL) on the growth of Colon-26, a Taxol-resistant murine tumor, when given at doses that included or exceeded the maximum tolerated dose (MTD). In contrast, Taxol liposomes delayed tumor progression at a dose that exceeded the MTD of free Taxol.
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PMID:Novel Taxol formulations: Taxol-containing liposomes. 791 32

Taxol is a promising anticancer agent under investigation for therapy of ovarian, breast, colon, and head and neck cancer. One problem associated with the administration of taxol is its low solubility in most pharmaceutically-acceptable solvents; the formulation used clinically contains Cremophor EL (polyethoxylated castor oil) and ethanol as excipients, which cause serious adverse effects. To eliminate this vehicle and possibly improve the antitumor efficacy of taxol, we have formulated taxol in liposomes of various compositions. Liposome formulations containing taxol and phospholipid in the molar ratio 1:33 were prepared from phosphatidylglycerol (PG) and phosphatidylcholine (PC) (1:9 molar ratio), and were physically and chemically stable for more than 2 months at 4 degrees C, or for 1 month at 20 degrees C. A method of producing taxol-liposomes by lyophilization has been developed, by which large batches can be prepared reproducibly in a 'pharmaceutically rational' manner. Taxol-liposomes retained the growth-inhibitory activity of the free drug in vitro against a variety of tumor cell lines. In mice, taxol-liposomes were well-tolerated when given in bolus doses by both iv and ip routes. The Maximum Tolerated Dose (MTD) was > 200 mg/kg; it exceeded that of free taxol, which had a MTD of 30 mg/kg by iv or 50 mg/kg by ip administration. Free taxol administered in the Cremophor vehicle was toxic at doses > 30 mg/kg, as was the equivalent volume of vehicle without drug.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Novel taxol formulations: preparation and characterization of taxol-containing liposomes. 793 31

C8KC is a new ketochlorin photosensitizer that must be formulated with an emulsifier because of its poor water solubility. In this report, we compare properties of Cremophor EL (CRM) and Tween 80 as delivery vehicles for C8KC. Unlike Tween 80, CRM altered the physical properties of both human and mouse plasma lipoproteins, resulting in decreased electrophoretic mobility of the individual lipoproteins along with the formation of a lipoprotein degradation product: a phospholipid fraction of low buoyant density. In human plasma, where there was sufficient low-density lipoprotein (LDL) for a distinction to be made, CRM caused a shift in binding of a ketochlorin from albumin to LDL and the degraded lipoprotein fraction. In mice bearing the RIF tumor, the use of CRM for drug formulation was associated with longer plasma and tissue persistence of C8KC, and enhanced photodynamic therapy (PDT) efficacy. These results indicate the importance of both sensitizer and vehicle as determinants of PDT efficacy.
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PMID:Biodistribution and PDT efficacy of a ketochlorin photosensitizer as a function of the delivery vehicle. 793 13

The photodynamic therapy (PDT) activity of the bis(dimethylthexylsiloxy)silicon 2,3-naphthalocyanine (SiNc 8) was evaluated against the EMT-6 tumor implanted intradermally in BALB/c mice. The SiNc 8 was formulated in aqueous emulsions based on Cremophor EL or Solutol HS 15. The formulation was shown to affect plasma clearance and overall pharmacokinetics. Compared to Cremophor, Solutol promoted rapid plasma clearance and high liver retention of the dye, combined with a slight increase of dye tumor concentrations. The PDT action spectrum for tumor response of SiNc 8 in Cremophor (190 mW cm-2, 200 J cm-2, 24 h postinjection [p.i.] of 1 mumol kg-1) showed a maximum at 780 nm, which corresponds to the absorption maximum of the monomeric dye as well as the in vivo maximum change in the "diffuse optical density" produced by the dye. The extent of tumor necrosis increased with augmented dye and light doses. Regardless of the formulation, at 1 h p.i. of 0.1 mumol kg-1 SiNc 8, PDT efficiency (190 mW cm-2, 400 J cm-2) was high but accompanied by severe damage to normal tissues, at 24 h p.i. PDT resulted in complete tumor regression in 80% of the animals without adverse effects to adjacent tissues, while at 72 h p.i. PDT induced no tumor response with Cremophor and only a partial response with Solutol. At the latter time point, plasma dye clearance was nearly complete while tumor tissue levels remained high, suggesting that tumor response correlates with plasma rather than tumor dye levels. Skin sensitivity of SKhI mice to solar-simulated radiation was lower with SiNc 8 as compared to Photofrin. Our data suggest the potential of SiNc 8 as a far-red absorbing photosensitizer in clinical PDT.
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PMID:Photodynamic activities and skin photosensitivity of the bis(dimethylthexylsiloxy)silicon 2,3-naphthalocyanine in mice. 857 Jul 40

Bis(di-isobutyl octadecylsiloxy)silicon 2,3-naphthalocyanine (isoBOSINC) is a representative of a group of naphthalocyanine derivatives with spectral and photophysical properties that make them attractive candidates for photodynamic therapy (PDT). Tissue distributions were studied in tumor-bearing rats as a function of delivery system and time following administration. The tumor model was an N-(4-[5-nitro-2-furyl]-2-thiazolyl) formamide (FANFT)-induced urothelial cell carcinoma transplanted into one hind leg of male Fischer 344 rats; isoBOSINC was delivered to the rats by intravenous injection of 0.50 mg/kg of body weight as a suspension either in 10% Tween 80 in saline (Tween) or 10% (Cremophor EL + propylene glycol) in saline (Cremophor). The isoBOSINC was isolated from several tissues and organs, as well as tumors and peritumoral muscles and skin. Quantitation was by a high-performance liquid chromatographic technique with detection that utilizes the native fluorescence of the naphthalocyanine derivative. Independent of the delivery system, the dye was retained in tumors at higher concentrations than in normal tissues, except for spleen and liver. The isoBOSINC retention in tumors was high and was vehicle dependent. For Tween, the maximal ratio of dye in tumor versus peritumoral muscle occurred 12 h after injection; for Cremophor, the maximal ratio occurred later, 336 h postinjection. When the drug was delivered in Tween, isoBOSINC in serum showed two compartment kinetics: half-lives of about 2 and 11 h were found for the distribution and the elimination phases, respectively. When Cremophor was the vehicle, the elimination half-life was about 20 h, and one compartment kinetics was observed. The latter findings may explain the generally higher levels of the dye attained by the tissues at later times with Cremophor as the vehicle. An interesting exception was that after 7 and 14 days postinjection in Tween, the levels of dye found in testes were six- to seven-fold higher than those found after Cremophor delivery. Levels of dye were very low or not detectable in the brain. Optimal parameters for PDT of tumors with this novel photosensitizer are clearly time- and vehicle-dependent, and future PDT studies will need to incorporate these modulators.
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PMID:Effect of delivery system on the pharmacokinetics and tissue distribution of bis(di-isobutyl octadecylsiloxy)silicon 2,3-naphthalocyanine (isoBOSINC), a photosensitizer for tumor therapy. 857 66

Nickel-2,3,7,8,12,13,17,18-octaacetic acid-5,10,15,20-tetra-[3-carboranyl-methoxyphenyl]-porphyrin octamethylester (NiTCP) was given in a Cremophor EL, a polyethoxylated castor oil, and propylene glycol emulsion to BALB/c mice bearing transplanted s.c. KHJJ mammary carcinomas. A total dose of 244 microg NiTCP/gram body weight (gbw) (54 microg B/gbw) was given in 6 i.p. injections over a 32 hr period. Observations of behavior and changes in body weight and chemical and hematological blood tests indicated little or no toxicity from NiTCP over a period of 6-90 hr after injections. Boron concentrations near tumor margins were 160-180 microg B/g at 41-90 hr after the last injection. Tumor:normal brain boron concentration ratios reached approx. 10:1 and tumor:blood ratios reached approx. 250:1 after 4 days. There was no evidence of thrombocytopenia or other potentially important toxicities. Our findings place NiTCP among the leading candidates for pre-clinical experiments aimed toward improvement upon the compounds being tested for boron neutron-capture therapy of glioblastoma multiforme.
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PMID:Synthesis of a nickel tetracarboranylphenylporphyrin for boron neutron-capture therapy: biodistribution and toxicity in tumor-bearing mice. 889 50

Fatty acid ester surfactants Cremophor EL and Solutol HS 15 were described earlier as modulators of multidrug resistance mediated by MDR1 P-glycoprotein (Pgp). We have shown that the most active components of these polydisperse surfactants are fatty acid-polyethylene glycol-fatty acid diesters (FA-PEG-FA). A new generation of Pgp-surfactant inhibitors of defined structure was therefore synthesized. In the present study we show that these compounds are also able to inhibit up-regulation of MDR1 gene expression caused by cytarabine (ARA-C) and doxorubicin in human tumor cell lines H9 and KB 3-1, which express minimal levels of MDR1 mRNA. The surfactant inhibitors, however, had no effect on the induction of MDR1 gene expression by protein kinase C agonists. Using a set of FA-PEG-FA diesters with various fatty acids and different lengths of the PEG domain, we demonstrated that the activity of diester preparations as inhibitors of drug-induced MDR1 activation was in proportion to their activity as inhibitors of Pgp function. Oleic and stearic acid diesters with PEG 900 (20 ethylene oxide units) were the most potent. The poloxamer analogs of these diesters demonstrated similar effects. In contrast, the well-known, structurally unrelated inhibitors of Pgp activity, verapamil, cyclosporin A and PSC 833, had no inhibitory effect on drug-induced MDR1 activation. The ability of FA-PEG-FA diesters to inhibit both Pgp function and drug-induced MDR1 activation suggests that these chemomodulators may be uniquely useful for the prophylaxis of Pgp-mediated multidrug resistance in drug-treated tumors.
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PMID:Inhibition of cytarabine-induced MDR1 (P-glycoprotein) gene activation in human tumor cells by fatty acid-polyethylene glycol-fatty acid diesters, novel inhibitors of P-glycoprotein function. 890 Apr 36

Taxol is a novel antitumor alkaloid that has shown clinical activity against several tumors. However, due to its low aqueous solubility, Cremophor EL (polyoxyethylated castor oil) and ethanol are used as excipients in the pharmaceutical drug formulations. These agents are implicated in hypersensitivity reactions. Hence the goal of this work was to design a novel Taxol formulation using polymeric nanoparticles to eliminate the Cremophor EL vehicle for drug delivery. Polyvinylpyrrolidone nanoparticles containing Taxol were prepared by a reverse microemulsion method. The size of the nanoparticles as determined by quasielastic light scattering was found to be between 50 and 60 nm. The antitumor effect of Taxol encapsulated nanoparticles was evaluated in B16F10 murine melanoma transplanted in C57B1/6 mice. The in vivo efficacy of Taxol-containing nanoparticles as measured by reduction in tumor volume and increased survival time was significantly greater than that of an equivalent concentration of free Taxol. These results suggest that encapsulation of Taxol in polymeric nanoparticles could be useful in improving its therapeutic efficacy in treatment of solid tumors.
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PMID:Novel Taxol formulation: polyvinylpyrrolidone nanoparticle-encapsulated Taxol for drug delivery in cancer therapy. 893 91

Paclitaxel, a recently approved antineoplastic agent, is cleared slowly from the peritoneal cavity after i.p. injection, and therefore appears to be promising for intracavitary therapy of malignancies confined to the peritoneal cavity. However the dose-limiting toxicity of Taxol, the clinical formulation of paclitaxel, was severe abdominal pain, likely caused by the excipients (Cremophor EL and ethanol) that are required to overcome low drug solubility. We tested the hypothesis that a liposome-based formulation could modulate paclitaxel toxicity independent of antitumor activity. The dose-dependence of toxicity and antitumor effect of paclitaxel liposomes was evaluated after i.p. administration against i.p. P388 leukemia. Liposomal paclitaxel showed antitumor activity similar to that of free paclitaxel (as Taxol), but was better tolerated by both healthy and tumor-bearing mice.
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PMID:Paclitaxel-liposomes for intracavitary therapy of intraperitoneal P388 leukemia. 894 23

Cremophor EL (CreEL), a polyethylene castor oil used as a vehicle for cyclosporin A and taxol, reverses P-glycoprotein-mediated drug resistance. The vehicle in an i.v. dosage form of PSC 833, [3'-keto-Bmt1]-[Val2]-cyclosporin, contains CreEL and has been presumed to have the potentiation of the reversal activity of PSC 833. To examine this possibility, we compared reversal activities of CreEL and PSC 833 against multidrug resistance (MDR) in vitro and in vivo. Both CreEL and PSC 833 inhibited P-glycoprotein-mediated efflux of [3H]vincristine from adriamycin-resistant myelogenous leukemia K562. The sensitization of multidrug-resistant cell lines to anticancer drugs by CreEL and PSC 833 was selective to MDR-related agents, suggesting a specific interference of the P-glycoprotein function by the two MDR modulators. The concentration-dependent activity of the modulators demonstrated that CreEL is at least 100 times less potent than PSC 833. The in vivo reversal effects of CreEL alone and PSC 833 in the vehicle were investigated in multidrug-resistant tumor-bearing mouse models. In vincristine-resistant P388 leukemia-bearing mice, neither i.v. nor i.p. administration of CreEL even at 1440 mg/kg enhanced the antitumor activity of adriamycin. The in vivo negligible activity of CreEL was confirmed in an HCT-15-bearing athymic mouse model. In contrast, PSC 833 significantly enhanced the antitumor activity of adriamycin in the in vivo models. The reversal activity of CreEL restricted to in vitro leads us to conclude that the vehicle containing CreEL did not potentiate the activity of PSC 833 in the tumor-bearing mouse models.
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PMID:Cremophor EL reversed multidrug resistance in vitro but not in tumor-bearing mouse models. 899 Nov 85


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