In vitro effect of dapsone on human chromosomes.

The proportion of accumulated metaphases, as well as the frequency of aneuploidies and structural chromosome aberrations were investigated in DDS-treated and untreated (controls) leukocyte cultures from two samples of healthy adult Caucasoid individuals. In one sample, the sulfone-treated cultures differed from the controls in that they contained 0.4 mug of DDS per ml of tissue culture medium plus phytohemagglutinin. In the other sample, these cultures differed from the controls in that they contained a tenfold higher concentration of DDS. The two concentrations of DDS used have not significantly affected the rate of metaphases, while 0.4 mug/ml DDS did not increase the frequency of chromosome aberrations. The same was not true for the cultures treated with 4 mug/ml DDS in which the proportion of aneuploides and achromatic gaps increased significantly.

Factors influencing the level of dapsone in blood.

The level of dapsone in the blood 4 and 6 h after the ingestion of the 7th daily dose of 100 mg of the drug was investigated in 36 adult males with leprosy who had normal renal function and were free of diarrhoea and emesis. The bimodal distribution of the dapsone levels at 6 h was shown by multiple regression analysis to be due to a negative correlation between this trait and the haematocrit value. Among the patients with high dapsone blood levels, 81.8% presented haematocrit values under 36%, whereas only 20% of those with low levels showed low haematocrit values. Partial regression coefficients, calculated for the dapsone level on the age, weight of the patient, estimated number of years since the onset of leprosy, number of years under sulfone treatment, and blood levels of haemoglobin, albumin, and globulins, did not show statistical significance.