A case report of dramatic increases in serum digoxin levels after alpr
azolam administration prompted our investigation. Twelve inpatients re
ceiving long-term digoxin (0.25 mg daily) randomly received oral admin
istration of either 1.0 or 0.5 mg alprazolam per day for 7 days. In ea
ch dosage group, three patients were older than and three were younger
than 65 years of age. The area under the concentration-time curve for
serum digoxin increased significantly in patients receiving 1 mg alpr
azolam daily, and this increase was more pronounced in patients older
than 65 years of age. Clinical digoxin toxicity developed in one elder
ly patient who was receiving 1 mg/day alprazolam.