Increased levels/effects w/ α1
-blockers, antifungal agents (azole derivatives), Ca channel blockers (nondihydropyridine), cyclosporine, strong & moderate CYP3A4 inhibitor, dasatinib, diazoxide, fluconazole, grapefruit juice, herbs (hypotensive properties), macrolide antibiotics, Mg salts, MAOIs, pentoxifylline, phosphodiesterase 5 inhibitors, prostacyclin analogues, PIs, quinupristin. Increase the levels/effects of amifostine, antihypertensives, CYP1A2 substrates, hypotensive agents, Mg salts, neuromuscular-blocking agents (non-depolarizing), nitroprusside, phenytoin, rituximab, tacrolimus. Decreased levels/effects w/ barbiturates, Ca salts, carbamazepine, strong CYP3A4 inducers, deferasirox, herbs (CYP3A4 inducers & hypertensive properties), methylphenidate, nafcillin, rifamycin derivatives, yohimbine, St. John's wort. Decrease levels/effects of clopidogrel, quinidine. Concurrent use w/ lithium potentially may result in the form of nausea, vomiting, diarrhea, ataxia, tremors, &/or tinnitus. May worsen HTN w/ ephedra, yohimbe, ginseng. Increased hypertensive effects w/ garlic.