Digoxin absorption is found to be decreased in patients with
malabsorption syndromes on the basis of mucosal defects. Since intestinal mucosa can be damaged by
cytostatic drugs, it was the purpose of these studies to investigate the influence of various
cytostatic drugs on
digoxin and
digitoxin plasma levels and urinary excretion. In 9 patients with
malignant lymphoma, who received 0.8 mg
beta-acetyldigoxin (n = 6) or 0.5 mg
digitoxin (n = 3) before and 24 h after combined
therapy with
cyclophosphamide,
vincristine,
procarbazine, and
prednisone (CVPP) or
cyclophosphamide,
vincristine and
prednisone (CVP), plasma
glycoside concentrations were measured 0 to 8 h after
digoxin and 0--168 h after
digitoxin application and the areas under the plasma concentration-time curves were calculated. In 12 patients on 0.3 mg
beta-acetyldigoxin and in 10 patients on 0.1 mg
digitoxin, daily plasma
glycoside concentrations and daily renal excretion were measured before and after CVPP, CVP or
cyclophosphamide,
vincristine,
cytarabine and
prednisone (CVAP) treatment schemes. The diminished steady-state plasma
digoxin concentrations and daily renal
glycoside excretion during the 24-168 h period after the
cytostatic dose demonstrate a reversible impairment of
digoxin absorption. In contrast
cytostatic drug therapy does not lead to reduction in steady-state
digitoxin plasma levels and daily renal
glycoside excretion. The delayed time to peak after a single dose of
digoxin or
digitoxin during
cytostatic drug therapy shows that rate of absorption of both
glycosides is reduced. Our results indicate the need for very exact monitoring of
digoxin dosage during
cytostatic therapy. The use of
digitoxin for these patients is an alternative in maintaining adequate digitalization.