May reduce the rate of absorption w/ antacid containing Al or Mg salts. Increased conc w/ nelfinavir. Theoretical possibility of ergotism w/ ergotamine derivatives. Possibility of increased digoxin levels. Elevated cyclosporine Cmax
. Increased phosphorylated zidovudine conc. Enhanced effect of astemizole, alfentanil. May increase QT interval prolongation, ventricular arrhythmias & Torsades de pointes w/ cisapride.