Losartan Drug Review: PTCB Exam Prep Guide

Losartan Overview for Pharmacy Technicians

Losartan is one of the most prescribed angiotensin II receptor blockers (ARBs) and a high-frequency drug on the PTCB certification exam. Understanding how losartan differs from ACE inhibitors is a key testable concept that pharmacy technicians must master.

Brand Name and Classification

Losartan is sold under the brand name Cozaar. A combination product with hydrochlorothiazide is available as Hyzaar. Losartan belongs to the angiotensin II receptor blocker (ARB) class, identified by the suffix -sartan. Other ARBs include valsartan (Diovan), irbesartan (Avapro), and olmesartan (Benicar).

Mechanism of Action

Losartan blocks angiotensin II type 1 (AT1) receptors, preventing angiotensin II from binding and causing vasoconstriction. Unlike ACE inhibitors, ARBs do not inhibit the breakdown of bradykinin, which means they are much less likely to cause the dry cough associated with ACE inhibitors. This is a critical PTCB exam distinction.

Common Indications

Hypertension: First-line or alternative therapy for high blood pressure
Diabetic nephropathy: Protects kidney function in type 2 diabetics with proteinuria
Heart failure: Alternative when ACE inhibitors are not tolerated
Stroke prevention: In hypertensive patients with left ventricular hypertrophy

Dosing Information

Losartan is available in 25 mg, 50 mg, and 100 mg tablets. The typical starting dose for hypertension is 50 mg once daily, with a maximum of 100 mg daily (can be given as a single dose or divided). For patients who are volume-depleted or taking diuretics, a lower starting dose of 25 mg is recommended.

Side Effects

Dizziness: Most commonly reported, especially at treatment initiation
Hyperkalemia: Similar to ACE inhibitors, monitor potassium
Hypotension: Especially in volume-depleted patients
Upper respiratory infection: Reported in clinical trials
Back pain and muscle cramps: Occasionally reported

Notably, losartan does not typically cause a dry cough. This is the primary reason patients are switched from ACE inhibitors to ARBs.

ARBs vs. ACE Inhibitors: PTCB Exam Comparison

Both lower blood pressure and protect kidneys
ACE inhibitors end in -pril; ARBs end in -sartan
ACE inhibitors cause dry cough (bradykinin accumulation); ARBs generally do not
Both can cause hyperkalemia and are contraindicated in pregnancy
ACE inhibitors can cause angioedema more frequently than ARBs
Both should not be combined with each other or with aliskiren in diabetic patients

PTCB Exam Tips

Key facts: losartan is brand Cozaar, ARBs end in -sartan, the main advantage over ACE inhibitors is no dry cough, and both classes are pregnancy Category D. Knowing the -pril vs -sartan distinction is essential for the exam.

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