To see whether the efficacy of butantrone in short-contact therapy could be increased by starting with a single high-concentration directly, 20 psoriatic patients were treated with dithranol (0.1,-0.5,-1.0,-2.0%) and butantrone (3.9%) short-contact therapy as a right-left comparison. With these treatment modalities the antipsoriatic effects of dithranol and butantrone were similar. Although the efficacy of 3.9% butantrone was better than the previously used butantrone therapy with gradually increasing doses, there was a parallel increase in side-effects.

Non-confluent monolayers of HeLa cells were treated with various concentrations (10(-5)-10(-8) M) of dithranol or butantrone for 45 min. The cells were then cultivated for up to 48 h and treated with 10 microM bromodeoxyuridine (BrdU) and 10 microM fluorodeoxyuridine for 30 min before harvesting. Both drugs at concentrations of 10(-6) and 10(-5) M inhibited the BrdU uptake of HeLa cells, but did not cause any significant change in the proportion of cells in S-phase. The highest (10(-5) M) concentration of butantrone caused an abrupt decrease in cell number.