Drug General Information (ID: DDI7Y0S8VQ)
Drug Name			Tamoxifen		Drug Info		Fostemsavir		Drug Info
Drug Type		Small molecule				Small molecule
Therapeutic Class		Antineoplastics				Antiviral Agents
Structure

Mechanism of Tamoxifen-Fostemsavir Interaction (Severity Level: Moderate)
Increased risk of prolong QT interval Click to Show/Hide Mechanism Graph
Drug Name		Tamoxifen				Fostemsavir
Mechanism		Prolong QT interval				Prolong QT interval
Key Mechanism Factor 1
		Factor Name		QT interval
		Factor Description		Long QT syndrome is a heart signaling disorder that can cause a fast, chaotic heartbeat (arrhythmia). Many people may not exhibit symptoms, and usually the condition is detected during routine medical tests. In others, the most common symptoms include: sudden fainting, palpitations, dizziness, seizures, sudden death.
Mechanism Description		Increased risk of prolong QT interval by the combination of Tamoxifen and Fostemsavir

Recommended Action
Management		Caution is recommended if fostemsavir is used in combination with other drugs that can prolong the QT interval. Consider obtaining electrocardiogram and serum electrolyte levels prior to initiating fostemsavir therapy and periodically thereafter, particularly in patients with risk factors for torsade de pointes and/or receiving one or more potent CYP450 3A4 inhibitors (e.g., azole antifungal agents cobicistat protease inhibitors ketolide and certain macrolide antibiotics ceritinib idelalisib nefazodone) or P-gp inhibitors (e.g., cyclosporine diltiazem quinidine quinine tacrolimus verapamil). Correct hypokalemia and/or hypomagnesemia before starting treatment and as indicated during treatment, as they may be risk factors for ventricular arrhythmias.

References
1	Product Information. Rukobia (fostemsavir). ViiV Healthcare, Research Triangle Park, NC.