Drug Interaction Report

MONITOR: The concomitant administration of estramustine and angiotensin enzyme converting (ACE) inhibitors may increase the risk of angioedema. The mechanism is unknown. Cases of angioedema have been associated with estramustine administration; many of these patients were also receiving ACE inhibitors.

MANAGEMENT: It is recommended to monitor patients for adverse reactions during concomitant therapy. Clinicians and patients should be aware of the potential for increased risk of angioedema when estramustine is prescribed with ACE inhibitors. Patients should be advised to promptly discontinue these medications and seek medical attention if they develop signs or symptoms suggestive of angioedema such as swelling of the face, extremities, eyes, lips, or tongue, and difficulty swallowing or breathing.

ADJUST DOSING INTERVAL: Food and milk may significantly decrease serum concentrations of estramustine. The mechanism of the interaction is not known.

MANAGEMENT: It is recommended that estramustine be taken at least 1 hour before or 2 hours after meals, and that it not be coadministered with milk, or calcium containing products.

GENERALLY AVOID: Moderate-to-high dietary intake of potassium can cause hyperkalemia in some patients who are using angiotensin converting enzyme (ACE) inhibitors. In some cases, affected patients were using a potassium-rich salt substitute. ACE inhibitors can promote hyperkalemia through inhibition of the renin-aldosterone-angiotensin (RAA) system.

MANAGEMENT: It is recommended that patients who are taking ACE inhibitors be advised to avoid moderately high or high potassium dietary intake. Particular attention should be paid to the potassium content of salt substitutes.