Losartan is a common prescription medication belonging to the class of drugs known as Angiotensin II Receptor Blockers (ARBs). Its primary action is to manage high blood pressure (hypertension) by blocking the effects of a hormone that naturally constricts blood vessels. Losartan is also prescribed to reduce the risk of stroke in patients with left ventricular hypertrophy and to protect the kidneys in individuals with type 2 diabetes and nephropathy. When Losartan causes side effects, is ineffective, or is medically contraindicated, providers seek alternative treatments. These alternatives target different physiological mechanisms to achieve the therapeutic goal of lowering blood pressure.
Angiotensin Converting Enzyme Inhibitors
Angiotensin Converting Enzyme Inhibitors (ACE-Is) are considered a first-line alternative to Losartan because they act on the same biological cascade, the Renin-Angiotensin System (RAS). Instead of blocking the receptor where Angiotensin II binds, ACE-Is block the enzyme responsible for creating it. This enzyme, called Angiotensin-Converting Enzyme, is prevented from converting the precursor Angiotensin I into the potent vasoconstrictor Angiotensin II.
By inhibiting this conversion, ACE-Is achieve the same result as Losartan: blood vessels relax and widen, which lowers blood pressure. Common examples include lisinopril, enalapril, and ramipril. They are widely used and are effective in treating hypertension, heart failure, and diabetic kidney disease.
A distinguishing characteristic of ACE-Is is the potential for a persistent, dry cough, which affects approximately 10% of patients. This side effect is caused by the buildup of bradykinin, which is normally broken down by the ACE enzyme. If a patient develops this bothersome cough, switching to an ARB like Losartan is often the solution.
In rare cases, both ACE-Is and ARBs can cause angioedema, a serious swelling of the deep layers of the skin. The risk of angioedema is slightly higher with ACE-Is, particularly in African American patients. Because their mechanism of action is otherwise very similar, ACE-Is are a comparable pharmacological option when Losartan is no longer appropriate.
Medications That Relax Blood Vessels
Calcium Channel Blockers (CCBs) are a major class of antihypertensive drugs that use a completely different mechanism than RAS-targeting drugs. CCBs work by limiting the movement of calcium ions into the smooth muscle cells of the heart and blood vessel walls. Since calcium is necessary for muscle contraction, blocking its entry causes the muscular walls of the arteries to relax, a process known as vasodilation.
This relaxation widens the blood vessels, reducing resistance and lowering blood pressure. CCBs are divided into two main categories based on their primary site of action. Dihydropyridines, such as amlodipine and nifedipine, primarily target the blood vessels and are effective for hypertension.
Non-dihydropyridines, including diltiazem and verapamil, affect the blood vessels but also slow the heart rate and reduce the force of heart muscle contraction. This makes them useful for treating certain heart rhythm issues in addition to high blood pressure. Common side effects of CCBs can include ankle swelling (edema) and flushing, particularly with the dihydropyridine type. Because their mechanism is independent of the RAS system, CCBs are a suitable alternative when a patient cannot tolerate Losartan or ACE-Is.
Medications That Reduce Fluid Volume
Diuretics, often called “water pills,” are an established class of medication for treating hypertension. Their mechanism involves increasing the excretion of sodium and water by the kidneys, which directly reduces the total volume of fluid circulating in the bloodstream. This decrease in fluid volume lessens the strain on the heart and blood vessels, thereby lowering blood pressure.
The most frequently prescribed type for managing uncomplicated hypertension are Thiazide diuretics, such as hydrochlorothiazide (HCTZ) and chlorthalidone. These agents work by inhibiting sodium reabsorption in the distal convoluted tubule of the kidney. Loop diuretics, like furosemide, are more potent and are reserved for patients with significant fluid retention issues, such as heart failure.
A potential concern with diuretic therapy is the disturbance of electrolyte balance, particularly the loss of potassium. Regular monitoring of electrolyte levels is necessary to ensure patient safety. Potassium-sparing diuretics exist and are sometimes used in combination with Thiazides to mitigate potassium loss.
Lifestyle Changes and Safe Transitioning
Non-pharmacological interventions are an important part of managing blood pressure and can sometimes reduce the required dosage or the need for medication. Dietary changes, such as adopting the Dietary Approaches to Stop Hypertension (DASH) eating plan, are highly effective. The DASH diet emphasizes consuming fruits, vegetables, and whole grains while limiting saturated fats and added sugars. Reducing dietary sodium intake is particularly impactful, with a goal of limiting consumption to 2,300 milligrams per day.
Regular physical activity, such as at least 150 minutes of moderate-intensity cardiovascular exercise per week, contributes significantly to lowering blood pressure. Maintaining a healthy body weight and limiting alcohol consumption further supports blood pressure control.
Transitioning away from a medication like Losartan requires professional medical guidance. Patients should never abruptly stop taking their prescribed blood pressure medication, as this can lead to a dangerous spike in blood pressure. A healthcare provider will evaluate individual health conditions and determine the most appropriate alternative, which may involve a gradual change or close monitoring during the switch.