Alters disposition of ritonavir. Hypertensive crisis w/ MAOIs. Increased BP w/ dihydroergotamine or linezolid, bromocriptine, pergolide, lisuride, cabergoline, ergotamine, methylergotamine & other vasoconstrictors (phenylpropanolamine, phenylephrine, ephedrine). Reduced effects of β-adrenergic blockers, methyldopa, guanethidine & reserpine. Hypertensive effect is potentiated by TCAs. Increased absorption by antacids & proton-pump inhibitors. Reduced absorption by kaolin. May provoke or worsen ventricular arrhythmia w/ halogenated anaesth agents eg, chloroform, enflurane, isoflurane, cyclopropane, halothane. Not recommended in digitalized patients.