Increased antihypertensive effects w/ α-blockers, diuretics; TCAs. Amlodipine: Increased BP-lowering effects w/ grapefruit or grapefruit juice. Increased exposure w/ CYP3A4 inhibitors (PIs, azole antifungals, macrolides eg, erythromycin or clarithromycin, verapamil or diltiazem). Potential lowering of plasma conc w/ CYP3A4 inducers (eg, rifampicin,
Hypericum perforatum). Simvastatin; dantrolene. Valsartan: Lithium; NSAIDs including selective COX-2 inhibitors, acetylsalicylic acid (>3 g/day) & nonselective NSAIDs. Increased systemic exposure w/ uptake transporter (rifampicin, ciclosporin) or efflux transporter (ritonavir).