Effect of magnesium--aluminum hydroxide and kaolin--pectin on absorption of digoxin from tablets and capsules.

Twelve healthy fasting volunteers received two 0.2-mg digoxin capsules or tablets with 60 ml water, 60 ml Maalox, or 60 ml Kaopectate in a randomized, single-dose, six-way crossover study. Concentrations of digoxin in multiple plasma samples and in all urine collected during the 24 hours after each dose were determined by radioimmunoassay. Compared to the water treatment, administration of both tablets and capsules with Maalox or Kaopectate reduced the peak digoxin plasma concentrations but did not significantly influence the time of peak concentration. Neither Maalox nor Kaopectate influenced the area under the 24-hour plasma concentration--time curve for either tablets or capsules. However, 24-hour urinary recovery of digoxin from tablets tended to be reduced by Maalox and Kaopectate; this was not the case with capsules. Digoxin capsules may have an advantage over currently available tablets in clinical situations requiring digoxin coadministration with nonabsorbable gastrointestinal preparations.