A comparative study on the cytogenetic activity of three benzodiazepines in vitro.

Even though benzodiazepines (BDZs) possess a leading place among drugs used as anxiolytics, sedatives, muscle relaxants, and anticonvulsants, their cytogenetic effects have not been widely studied in humans. Alprazolam (AZ), bromazepam (BZ), diazepam, and lorazepam (LZ) are some of the most commonly prescribed BDZs. Previous positive findings on diazepam's cytogenetic effects in human lymphocytes suggested additional investigation. In the present research, we explored the cytogenetic potential of AZ, BZ, and LZ in human lymphocyte cultures, using an expanded sample set, administering the under-investigation medications at final concentrations equivalent to oral dosage. As a biomarker of genotoxicity we used sister chromatid exchanges, one of the most sensitive methods reflecting DNA damage and/or subsequent DNA repair, and as a marker of cytostaticity we estimated the proliferation rate index. After 72 h of incubation in the cultures, all three BDZs caused a concentration-dependent, statistically significant increase of sister chromatid exchange frequency (p < 0.001) followed by a statistically significant decrease of proliferation rate index (p < 0.001) of lymphocytes. Our conclusive results suggest that AZ, BZ, and LZ, at concentrations equivalent to oral doses, exhibit statistically significant genotoxicity in human lymphocyte cultures.

Antineoplastic and cytogenetic effects of chlorpromazine on human lymphocytes in vitro and on Ehrlich ascites tumor cells in vivo.

The inhibitory effect of phenothiazines in tumor growth and cancer cell proliferation in vitro and in vivo has been established. These reports motivated us to investigate the genotoxic, cytotoxic, and cytostatic potential of chlorpromazine, alone or in combination with mitomycin C, in vitro and in vivo. Sister chromatid exchange levels were assessed providing a quantitative index of genotoxicity. In-vitro studies were performed on human lymphocyte cultures and in-vivo studies involved Ehrilch ascites tumor (EAT) cells. An antitumour study was also conducted on the survival time and the ascitic volume in EAT-bearing Balb/C mice. The combination of chlorpromazine plus caffeine and mitomycin C exerted cytostatic and cytotoxic actions in human lymphocytes. The combination of chlorpromazine plus mitomycin C exerted cytostatic and cytotoxic actions in EAT cells, significantly increased the survival span of the mice inoculated with EAT cells, and suppressed the expected tumor growth increase. The findings of this basic study illustrate that high chlorpromazine concentrations increase chemotherapeutic effectiveness of mitomycin C. Chlorpromazine concentrations within the observed human plasma concentration range need to be tested along with antineoplastic agents in vitro for its synergistic action so as to evaluate a potential clinical application. Further investigation including other phenothiazines, biological systems, and cancer models is required.