What may occur if Lisinopril is suddenly discontinued?

When Lisinopril, an ACE inhibitor used primarily for hypertension and heart failure, is suddenly discontinued, rebound hypertension can occur. This phenomenon is characterized by a significant increase in blood pressure that may exceed the patient's previous baseline levels before treatment was initiated.

The mechanism behind this is that when Lisinopril is abruptly stopped, the inhibition of the angiotensin-converting enzyme is removed. This loss of effect leads to an increase in the production of angiotensin II, a potent vasoconstrictor, which can result in a swift rise in blood pressure. Patients who have been on Lisinopril for an extended period may experience this rebound effect particularly pronouncedly.

Hypotension, which is low blood pressure, would not be a concern when discontinuing Lisinopril, especially if done suddenly, as the therapeutic effects would rapidly diminish, allowing the blood pressure to rise. While hyperkalemia (high potassium levels) and acute renal failure are potential side effects associated with the use of Lisinopril, these are not direct consequences of stopping the medication abruptly. Instead, they are risks that need monitoring while the drug is being used rather than following its discontinuation.