The Effect of Penicillamine on Serum Digoxin Levels

The effect of 1 Gm of penicillamine (pen) on serum digoxin levels (SDLs) of 3 groups of patients (Pts) on maintenance digoxin therapy was studied. Each group served as its own control. Group I (10pts) had serum digoxin measurements (SDMs) 2, 4, and 6 hours (hrs) after receiving their daily oral doses of digoxin. The next day SDMs were made similarly following 1 Gm of pen 2 hrs after administration of digoxin. In all pts the SDLs were significantly lower 2, 4, and 6hrs after receiving pen (1.86±0.25 VS 1.62±0.22, 1.80±0.17 VS 1.44±0.26, 1.87±0.27 VS 1.14±0.24 ng/ml, mean±SD with respective p values <0.025, <0.005 and <0.001). In order to exclude the interference of pen on digoxin absorption, Group II (13pts) had SDMs 22 hrs after their last oral doses of digoxin before and 6hrs after receiving 1 Gm of pen. In this group SDLs were also significantly reduced (1.50±0.48 VS 1.16±0.51 ng/ml, mean±SD, p <0.05). Group III (10pts) received maintenance intravenous digoxin for 5 days prior to SDM. In this group also marked reduction of SDM was observed 4 and 6hrs following 1 Gm of pen (1.36±0.50 VS 1.04±0.40, 1.46±0.69 VS 0.50±0.64ng/ml, mean±SD with p values of <0.001 and <0.005, respectively). It can be concluded that oral penicillamine reduces SDL significantly in digitalized pts irrespective of the route of digoxin administration and may be of significant value in management of digitalis toxicity.