Extensive intracellular accumulation of ID-6105, a novel anthracycline, in SK-OV-3 ovarian cancer cells.

We investigated the anticancer activity of 11-hydroxyaclacinomycin X (ID-6105), a novel anthracycline, on weakly doxorubicin (Dox)-resistant SK-OV-3 ovarian cancer cells, and elucidated the relationship between its anticancer activity and accumulation in cells compared with those of Dox. Accumulation of ID-6105 in the cells was time-and concentration-dependent, a result of drug-induced cytotoxicity in the cells. SK-OV-3 cells were preloaded with ID-6105 or Dox for 12 h at concentrations ranging from 100 to 2000 nM and then incubated with drug-free medium for 0-48 h. Cell viability was measured using a proliferation-based assay (XTT assay). The inhibitory effects of ID-6105 on cell viability were more pronounced than those of Dox. The IC(50) values of ID-6105 after 24-and 48-h incubation with drug-free medium were 1.58 and 0.084 microM, while those of Dox were 2 and 0.334 microM, respectively. To investigate the relationship between the intracellular levels and the cytotoxic effects of the drugs, we preloaded SKOV-3 cells with ID-6105 or Dox (100-2000 nM) for 12 h and then measured the intracellular levels of drugs by HPLC in drug-free medium for 0-48 h. After preloading the drugs, the intracellular concentrations of ID-6105 at time 0 were 1.3-, 1.8-, and 1.4-fold larger than those of Dox at initial concentrations of 500, 1000, and 2000 nM, respectively. The extent of ID-6105 accumulation in the cells was more pronounced than that of Dox. These findings suggest that ID-6105 effluxed less from the cells than Dox, resulting in its extensive cytotoxicity compared with that of Dox. These results show that accumulation of ID-6105 within tumor cells may be important for the inhibitory effects of this drug in cancer cells. ID-6105 has an antiproliferative effect on SK-OV-3 cells that is due to its cytotoxicity. This effect is more pronounced than that of Dox, and may be attributed to extensive accumulation of ID-6105 in the cells.

Surfactant effects upon dissolution patterns of carbamazepine immediate release tablet.

The objective of this study was to investigate the effects of sodium lauryl sulfate upon the saturation solubility of carbamazepine, its dissolution kinetics, and T50% defined as the time required for dissolving 50% of carbamazepine. Water, 0.1 N-HCl, and phosphate buffers at pH 4.0 and 6.8 containing 0.1, 0.5, 1, and 2% sodium lauryl sulfate were used as dissolution media. The dissolution study was conducted by using the USP dissolution apparatus II with an agitation rate of 75 rpm. Samples of the dissolution media were taken in 7, 15, 30, 45, 60, 75, and 90 min, and the amounts of carbamazepine were determined spectrophotometrically at 285 nm. All dissolution data were fitted well into a four-parameter exponential equation: Q = a(1 - e(-b x t)) + c(1 - e(-d x t)). In this equation Q represented % carbamazepine dissolved at a time t, and a, b, c, and d were constants. This equation led to the calculation of dissolution rates at various time points and T50%. It was found that the dissolution rate of carbamazepine was directly proportional to the aqueous concentration of sodium lauryl sulfate. In addition, under our experimental conditions T50% values ranged from 37.8 to 4.9 min. It was interesting to note that T50% declined rapidly as the surfactant concentration increased from 0.1 to 0.5%, whereas it declined more slowly at concentrations greater than 1%. These results clearly demonstrated that the dissolution rate of carbamazepine and duration of its dissolution test could be tailored by optimizing the amount of sodium lauryl sulfate in a dissolution medium.