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  • 1
    Electronic Resource
    Electronic Resource
    Prediction of ACNU plasma concentration-time profiles in humans by animal scale-up (1990)
    Springer
    Cancer chemotherapy and pharmacology 27 (1990), S. 20-26 
    Details
    ISSN: 1432-0843
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Plasma concentration-time profiles of nimustine hydrochloride, 1-[(4-amino-2-methyl-5-pyrimidinyl)methyl]-3-(2-chloroethyl)-3-nitrosourea hydrochloride (ACNU), in the mouse, rat, rabbit, and dog were determined by high-performance liquid chromatographic analysis. The pharmacokinetic parameters for these four animal species and previously reported clinical data were analyzed for investigation of interspecies correlation. Loglog plots of body weight (W; kg) vs total plasma clearance (CLtot, p; ml/min) and steady-state distribution volume (Vd, ss; 1) for the four animal species were linear, with high correlation coefficients (r 0.996 for both parameters), despite the fact that the nonrenal clearance was 〉97% in these species. Linear regression on the plots excluding human data yielded allometric equations (CLtot,p=50.6 W0.957; Bd, ss=1.29 W1.03) that were extrapolated to predict ACNU pharmacokinetic parameters in humans. For both parameters, however, there were 3-fold differences between the predicted and observed parametric values. To investigate these discrepancies, we measured serum protein binding of ACNU in these animal species and in humans. The values of CLtot,p and Vd,ss were converted into those of CLu tot,p and Vd,u ss, which correspond to the parameters for unbound ACNU. In this case, correlation coefficients of the log-log plots excluding human data (CLu tot,p=71.7 W0.891; Bd,u ss=1.82 W0.966) were also high (r≥0.991). The extrapolated values vs those observed in a 70-kg human were the following: CLu tot,p, 3,160 vs 2,290 ml/min; Vd,u ss, 110 vs 1061. Thus, the animal data were successfully extrapolated to yield better predictions of human pharmacokinetic parameters if the analysis was based on the unbound plasma concentration of ACNU. In addition, the predicted plasma concentration-time profile for humans also showed good agreement with the observed ones. These results suggest the importance of measuring unbound fractions of drugs for more accurate prediction of human pharmacokinetic parameters by extrapolation of animal data to the human situation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00689271
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  • 2
    Electronic Resource
    Electronic Resource
    Cell killing action of cell cycle phase-non-specific antitumor agents is dependent on concentration-time product (1988)
    Springer
    Cancer chemotherapy and pharmacology 21 (1988), S. 185-190 
    Details
    ISSN: 1432-0843
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Based on a pharmacokinetic model proposed by Jusko, which assumes that the cell killing action of cell cycle phase-non-specific agents occurs as a bimolecular reaction depending on drug concentration and cell density, we derived a cell kill kinetic equation for these drugs, including the decomposition constant in culture medium. This equation revealed that the cell killing activity of these drugs depends on the value of concentration x exposure time or the area under the drug concentration-time curve (AUC). It was also clarified that the curves for concentration-exposure time necessary for 90% cell kill on a log scale simulated on the basis of the equation differ according as whether drugs are stable or unstable in the culture medium, being expected to be linear with a slope of-1 in the former case, and to take the form of an asymptotic curve in the latter. For three cell cycle phase-non-specific agents, mitomycin C (MMC), 1-(4-amino-2-methylpyrimidine-5-yl)-methyl-3-(2-chloroethyl)3-nitrosourea hydrochloride (ACNU), and nitrogen mustard (HN2), we assessed the concentrations necessary for 90% cell kill (IC90) with various exposure times and the degradation rate constants under the culture conditions used. MMC was quite stable during the incubation, while ACNU and HN2 were unstable. When IC90's and exposure times were plotted on the above-mentioned graph, a linear relationship with a slope of-1 was seen for MMC, while for ACNU and HN2 the anticipated asymptotic curves resulted. We also ascertained that the decomposition constants for ACNU and HN2 expected on the basis of these curves showed a good agreement with the corresponding experimentally observed values. These results indicate that the cell killing action of cell cycle phase-non-specific drugs can be well described by a pharmacodynamic model and equation employing their decomposition constants and are dependent on the concentration-time product.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00262767
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  • 3
    Electronic Resource
    Electronic Resource
    Comparison of cellular basis of drug sensitivity of human colon, pancreatic, and renal carcinoma cell lines with that of leukemia cell lines (1988)
    Springer
    Cancer chemotherapy and pharmacology 22 (1988), S. 41-46 
    Details
    ISSN: 1432-0843
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In an attempt to find how much the low therapeutic effectiveness of antitumor drugs against so-called chemotherapy-refractory tumors such as colon carcinoma depends on drug sensitivity at the cellular level, sensitivity of five carcinoma cell lines (three colorectal, one pancreatic, and one renal) to nine typical anticancer agents was compared in vitro with that of four generally chemotherapysusceptible leukemia cell lines. Sensitivity was assesed in terms of the percentage cell growth in control cultures, which was determined by exposing exponentially growing cells for 48 h to the following antitumor drugs: 1-(4-amino-2-methylpyridine-5-yl)-methyl-3-(2-chloroethyl)3-nitrosourea hydrochloride (ACNU), adriamycin (ADM), bleomycin (BLM), cisplatin (DDP), etoposide (VP-16), 5-fluorouracil (5FU), mitomycin C (MMC), methotrexate (MTX), and vinblastine (VLB). As expected, 10-fold or greater differences in sensitivity were scarcely ever observed between the two kinds of cell lines. Thus, we recorded a result of more (or less) sensitivity when there was a difference of 3-fold or more; and compared the drug sensitivity in every pair of carcinoma and leukemia cell lines (20 pairs for each drug). We found that carcinoma cell lines were less sensitive to VP-16, ADM, DDP, and MTX than leukemia cell lines in 18, 15, 12, and 10 of 20 pairs, respectively; only one opposite case was observed, with DDP. On the other hand, no such tendency between the two groups was observed with BLM, 5FU, or MMC. Overall, significantly different sensitivities were observed between them in 91 out of 180 pairs (i.e., 9 antitumor drugsx5 carcinomasx4 leukemias), and carcinoma cell lines were less sensitive than leukemia cell lines in 79 of these 91 pairs. These results suggest that the refractoriness of colon carcinoma, etc. to chemotherapy is, at least in part, due to low drug sensitivity of the tumor cell itself.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00254179
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  • 4
    Electronic Resource
    Electronic Resource
    Kinetic analysis of the in vitro cell-killing action of neocarzinostatin (1989)
    Springer
    Cancer chemotherapy and pharmacology 23 (1989), S. 279-282 
    Details
    ISSN: 1432-0843
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The relationship between the drug concentration and exposure time of neocarzinostatin (NCS) for a definite cell-killing effect was kinetically analyzed, taking into consideration its loss in biological activity during incubation. Its cell-killing activity was determined by a colony-forming inhibition assay, which was conducted at room temperature (25° C) for 0.5–30 min exposure and at 37° C for 5 min-96 h exposure. Drug degradation at both temperatures was also investigated by bioassay. NCS lost its biological activity much faster at 37° C than at 25° C and the rate of loss in activity was higher at the lower initial concentration. Thus, the initial NCS concentrations necessary for 90% cell kill corresponding to each exposure time and a drug degradation constant were applied to a mathematical equation for the cell-killing effect of cell-cyclephase-nonspecific agents. As a result, the curves for IC90-exposure time relationships predicted from drug degradation constants for 37° C and 25° C were fairly well fitted to the respective experimental data. These results indicate that the cell-killing action of NCS can be expressed by this mathematical equation with scrutiny of drug degradation and is dependent on the concentration-time product (C x T).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00292404
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