A comparative study of the cytogenetic and antineoplasmatic effects induced by carboplatin in combination with niacin in human lymphocytes in vitro and in Ehrlich ascites tumor cells in vivo.

Enhanced sister chromatid exchange (SCE) levels and cell division delays were observed when cultured human lymphocytes treated with carboplatin (cPt) were exposed to niacin. Cytogenetic damage was also observed by cPt when Ehrlich ascites tumor (EAT) cells were exposed in vivo to nontoxic concentrations of niacin. One hour before intraperitoneal injection of 5-bromodeoxyuridine, adsorbed to activated charcoal, EAT-bearing mice treated intraperitoneally with cPt appeared to have a dose-dependent increase in SCEs and cell division delays. Niacin increased the survival time of the EAT-bearing mice treated with cPt and markedly reduced the ascitic volume. Therefore the in vivo antitumor effect of cPt in conjunction with niacin appears to correlate well with the in vitro or in vivo synergistic effects on cytogenetic damage caused by the combined cPt plus Niacin treatment upon human lymphocytes or EAT cells, respectively.