Additive effect of DL-penicillamine plus Prussian blue for the antidotal treatment of thallotoxicosis in rats

DL-penicillamine (DL-P) and Prussian blue (PB) given alone or in combination were tested as possible treatments against acute thallium toxicity. Rats were intoxicated by i.p. injection of thallium (I) acetate at LD(50) (32 mg/kg). A day later, pharmacological treatment was administered until day 4 as follows: (1) vehicles, (2) PB 50mg/kg, by oral route, twice a day, (3) DL-P 25mg/kg i.p. route, twice daily and (4) PB+DL-P. The Estimated Probability Survival (EPS) was recorded during the experiment for each treatment. DL-P alone did not show a significant effect on survival. However, when it was used in combination with PB, it increased the survival significantly (EPS=0.8, P<0.05) as compared to the control group (EPS=0.4). In a different experiment, using 16 mg/kg of Thallium I acetate, the metal levels were analyzed in blood, body organs and brain regions after treatments. DL-P given alone decreased slightly the thallium content in blood, organs and brain. Meanwhile, its administration in combination with PB diminished the thallium levels significantly (P<0.05) in the majority of tissues, at levels lower than those achieved in the PB group. Those results indicate that DL-P administered alone did not prevent the mortality nor accumulation of the metal in body tissues. Its combination with PB could be considered an alternative antidotal treatment in thallium toxicity, because this chelating agent given alone did not cause thallium redistribution to the brain. When given in combination with PB it has an additive effect in the treatment of acute thallotoxicosis.