Drug Interaction Report

MONITOR: Coadministration with vadadustat, an organic anion transporter 3 (OAT3) inhibitor, may increase the plasma concentrations and the risk of adverse effects of drugs that are substrates of OAT3. A drug interaction study evaluating the effect of repeat doses of vadadustat (600 mg once daily) on the pharmacokinetics of furosemide, an OAT1/OAT3 substrate, showed a 2-fold increase in furosemide systemic exposure (AUC).

MANAGEMENT: Caution is advised if vadadustat is used in combination with organic anion transporter 3 (OAT3) substrates. Monitoring for signs and symptoms of increased exposure to the OAT3 substrate should be considered whenever vadadustat is added to or withdrawn from therapy. The prescribing information for concomitant medications may be consulted to assess the benefits versus risks of coadministration, as well as any dosage adjustments that may be required during coadministration and/or following the discontinuation of an OAT3 inhibitor.

MONITOR: Smoking and alcohol consumption during therapy with vadadustat may increase the risk of gastrointestinal erosions. Serious erosions, including gastrointestinal bleeding and the need for red blood cell transfusions, have been reported during vadadustat clinical trials. Patients with a history of gastrointestinal erosion, peptic ulcer disease, and current tobacco smokers and alcohol drinkers may be at higher risk of gastrointestinal injury.

MANAGEMENT: Caution is advised if vadadustat is prescribed to current tobacco smokers or alcohol drinkers. Patients should be advised to contact their physician if they develop potential signs and symptoms of gastrointestinal injury such as abdominal pain, hematemesis, trouble swallowing, chest or throat pain, and/or black, tarry stools.

H2 antagonists may reduce the clearance of nicotine. Cimetidine, 600 mg given twice a day for two days, reduced clearance of an intravenous nicotine dose by 30%. Ranitidine, 300 mg given twice a day for two days, reduced clearance by 10%. The clinical significance of this interaction is not known. Patients should be monitored for increased nicotine effects when using the patches or gum for smoking cessation and dosage adjustments should be made as appropriate.