May reduce the rate of absorption w/ antacids containing Al or Mg salts. Increased conc w/ nelfinavir. Theoretical possibility of ergotism w/ ergotamine derivatives. Possibility of increased digoxin levels. Elevated cyclosporine C
max & AUC
0-5. Increased phosphorylated zidovudine conc. Enhanced effect of astemizole, alfentanil. May increase QT interval prolongation, ventricular arrhythmias & Torsades de pointes w/ cisapride.