Imdur (Isosorbide Mononitrate) as an Antihypertensive
Imdur is not recommended as a primary antihypertensive agent for routine blood pressure management, as nitrates have not been shown to be useful in the treatment of hypertension and tolerance limits their long-term effectiveness. 1, 2
Primary Role: Angina Management, Not Hypertension
Isosorbide mononitrate is indicated for the treatment and prevention of angina pectoris in patients with coronary artery disease, not as a first-line or routine antihypertensive medication. 1, 2
Major hypertension guidelines (ACC/AHA 2017, AHA/ACC/ASH 2015) do not include nitrates in their recommended antihypertensive drug classes, which consist of ACE inhibitors, ARBs, calcium channel blockers, thiazide diuretics, and beta-blockers. 1
Long-acting nitrates are specifically used for angina control in hypertensive patients with coronary artery disease, but this is for symptom management rather than blood pressure reduction. 1
The Tolerance Problem
Nitrate tolerance has fundamentally limited the ability of long-term nitrates alone to be effective as antihypertensive agents. 1, 2
Continuous nitrate exposure leads to tolerance development, which can be minimized only by providing a "nitrate-free interval" of at least 10 hours daily. 2
This dosing requirement (with nitrate-free periods) makes nitrates impractical for 24-hour blood pressure control, which is the goal of antihypertensive therapy. 2
Limited Evidence for Blood Pressure Reduction
While some research suggests blood pressure effects, the evidence is weak and context-specific:
One small study (n=16) in patients with systolic hypertension showed that extended-release isosorbide mononitrate 60-120 mg daily reduced systolic blood pressure by approximately 16 mmHg after long-term use (16-109 months), but this was as adjunct therapy in patients refractory to conventional treatment. 3
A study in maintenance hemodialysis patients (n=144) showed blood pressure reduction with isosorbide mononitrate 30-120 mg daily, but this represents a highly specific population with unique pathophysiology (elevated ADMA levels and endothelial dysfunction). 4
These studies do not establish efficacy for general hypertension management and represent special circumstances rather than routine practice. 4, 3
Specific Clinical Context: Heart Failure
The only guideline-endorsed use of nitrates for blood pressure management is in a very specific population:
For African American patients with NYHA class III or IV heart failure with reduced ejection fraction, the combination of hydralazine plus isosorbide dinitrate is recommended together with ACE inhibitors, beta-blockers, and aldosterone antagonists. 1, 2
This recommendation is based on the A-HeFT trial, which showed reduced mortality (10.2% vs 6.2%, P=0.02) in this specific population. 1
The addition of hydralazine to the nitrate reduces tolerance and provides blood pressure control as a secondary benefit, not as the primary therapeutic goal. 1
Critical Safety Concerns
Isosorbide mononitrate is absolutely contraindicated with phosphodiesterase inhibitors (sildenafil, tadalafil) due to risk of profound hypotension, myocardial infarction, and death. 2
Should be avoided in patients with severe hypotension (systolic BP <90 mmHg). 2
Use with extreme caution in aortic stenosis, as marked hypotension may occur. 2
Common side effects include headache (often limiting therapy), hypotension, and dizziness. 2
Recommended Antihypertensive Approach Instead
For patients requiring blood pressure management, use evidence-based first-line agents:
Thiazide or thiazide-like diuretics (chlorthalidone preferred), ACE inhibitors or ARBs, and calcium channel blockers are the recommended first-line antihypertensive agents. 1
Beta-blockers are added when there is compelling indication (prior MI, heart failure, stable angina). 1
Target blood pressure for most patients with coronary artery disease is <140/90 mmHg (Class IIa), with consideration of <130/80 mmHg in selected patients (Class IIb). 1