Drug Interaction Report

MONITOR: Drugs that decrease clotting, vasoconstriction, or platelet aggregation may interfere with the therapeutic effect of verteporfin. These agents may antagonize the physiologic responses to local damage of neovascular endothelium induced by activated verteporfin, which include the release of procoagulant and vasoactive factors that result in vessel occlusion. However, the clinical significance is unknown.

MANAGEMENT: If possible, agents such as anticoagulants, thrombolytics, platelet inhibitors, nonsteroidal anti-inflammatory drugs, ginkgo, dong quai, and vasodilators should be discontinued prior to verteporfin therapy. Otherwise, the potential for diminished efficacy of verteporfin should be considered.

GENERALLY AVOID: The concurrent use of ethanol and alpha-1 adrenergic blockers may cause increased hypotensive effects. Patients with aldehyde dehydrogenase deficiencies (primarily Asians) may be at a higher risk of this interaction. The mechanism has not been determined. Data exist for prazosin and other alpha adrenergic blockers are expected to interact also. In addition, any patients taking alpha adrenergic blockers may experience excessive orthostatic hypotension with ethanol ingestion, due to ethanol's unopposed vasodilatory effects in the presence of alpha adrenergic blockade.

MANAGEMENT: Patients who develop a flushing reaction after ethanol ingestion (indicates a possible aldehyde dehydrogenase deficiency) should be advised to avoid ethanol or limit their intake. All patients should be warned about the possibility of orthostatic hypotension with concurrent ethanol use.