Cytotoxic and immunomodulative effects of flunitrazepam, zipeprol and trihexyphenidyl on human peripheral blood lymphocytes

The cytotoxic effects of flunitrazepam, zipeprol and trihexyphenidyl on cel l viability of peripheral blood mononuclear cells from healthy volunteers w ere studied at concentrations from 10(-2) to 10(-8) M by 2 colorimetric in vitro assays: the neutral red uptake assay and thiazolyl blue tetrazolium b romide assay. All tested drugs of abuse were non-cytotoxic at concentration s lower than 10(-5) M. Possible immunomodulative effects of these substance s were evaluated through phytohemagglutinin induced lymphocyte proliferatio n ([H-3]-thymidine DNA incorporation assay) and by a Cr-51 release natural killer assay. The 3 drugs studied produced statistically significant immuno modulative alterations on both immunological parameters.