jan asked
I was prescribed Benicar (olmesartan) 5mg two times daily for hypertension. Due to the shortage, my doctor has prescribed Cozaar (losartan), 25mg two times daily. Why the increase in dosage?
Answer
Both Benicar (olmesartan) and Cozaar (losartan) are classified as ARBs (Angiotensin Receptor Blockers).
These drugs work by blocking angiotensin II from binding to AT1 receptors, which has a variety of resulting effects.
In a nutshell, when angiotensin II does bind to AT1 receptors, the following occurs:[1]
- Reabsorption of sodium from the kidney, which increases the retention of water.
- Vasoconstriction (narrowing of the blood vessels).
- Increased secretion of the hormone aldosterone.
Since ARB drugs block angiotensin II from binding to AT1 receptors, they inhibit the above effects from happening, which results in a decrease in blood pressure, water retention and a reduction in risk of certain cardiovascular events, like a heart attack.
There are several ARB drugs available on the market, including:
- Benicar (olmesartan)
- Cozaar (losartan)
- Diovan (valsartan)
- Micardis (telmisartan)
- Edarbi (azilsartan)
- Atacand (candesartan)
- Avapro (irbesartan)
Even though all ARBs work the same way and are effective in treating high blood pressure, many have different FDA-approved indications. Additionally, they have different effective dosing ranges (i.e. potency).
Comparing Benicar And Cozaar
In this section, I will go over a few major categories (e.g. dosing, indications etc...) to help you compare Benicar and Cozaar.
Since your question is regarding dosing, we will discuss that first.
Dosing
Benicar (olmesartan) and Cozaar (losartan) have different dosage ranges and potencies, so you can't compare them on a milligram to milligram basis.
Benicar (olmesartan) is available in the following dosages:
- 5 mg
- 10 mg
- 20 mg
- 40 mg
Cozaar (losartan) is available in the following dosages:
- 25 mg
- 50 mg
- 100 mg
As you can see, Benicar (olmesartan) is a more potent drug, on a milligram basis, than Cozaar (losartan).
Since you were taking the lowest dose of Cozaar (losartan), it appears your doctor wants you to start on the lowest dose of Benicar (olmesartan), which is 5 mg.
I do want to note that both Benicar (olmesartan) and Cozaar (losartan) are FDA-approved to be dosed once daily.
However, studies have shown that dosing Cozaar (losartan) twice daily may be more effective in lowering blood pressure and reducing the risk of cardiovascular risk. This has not been shown with Benicar (olmesartan) though, and the prescribing information for the drug even states:[2]
"Twice-daily dosing offers no advantage over the same total dose given once daily."
Indications
Benicar is indicated for:
- Hypertension (increased blood pressure)
Cozaar is indicated for:
- Hypertension (increased blood pressure)
- Diabetic nephropathy
- Stroke prophylaxis
- Proteinuria
Effectiveness
In terms of their blood pressure control, both Cozaar and Benicar are effective. However, studies show that Benicar typically has stronger blood pressure lowering effects at lower doses.[3]
Below is a range of blood pressure reductions compiled from various studies for each drug.[4]
Olmesartan 5 mg/day
- Systolic blood pressure reduction: 11-13 mmHg
- Diastolic blood pressure reduction: 8-12 mmHg
Olmesartan 10 mg/day
- Systolic blood pressure reduction: 10-17 mmHg
- Diastolic blood pressure reduction: 13-18 mmHg
Olmesartan 20 mg/day
- Systolic blood pressure reduction: 11-21 mmHg
- Diastolic blood pressure reduction: 4-17 mmHg
Olmesartan 40 mg/day
- Systolic blood pressure reduction: 5-22 mmHg
- Diastolic blood pressure reduction: 5-17 mmHg
Losartan 25 mg/day
- Systolic blood pressure reduction: 8-12 mmHg
- Diastolic blood pressure reduction: 7-10 mmHg
Losartan 50 mg/day
- Systolic blood pressure reduction: 8-19 mmHg
- Diastolic blood pressure reduction: 5-15 mmHg
Losartan 100 mg/day
- Systolic blood pressure reduction: 9-12 mmHg
- Diastolic blood pressure reduction: 9-10 mmHg
There are no studies that directly compare Benicar (olmesartan) and Cozaar (losartan) on properties other than blood pressure lowering (like a reduction in cardiovascular risk).
We do know that drugs have different potencies and differ in how strongly they bind to the AT1 receptor (Benicar binds far more strongly than Cozaar). Whether or not this is clinically significant isn't well known.[5]
Side Effects
The side effect profiles between Cozaar and Benicar are similar since they work the same way.[6]
These side effects include:
- Cough (although this is less common than with the ACE-Inhibitor class)
- Dizziness
- Lightheadedness
- Low blood pressure
- Nausea
- Diarrhea
- Fatigue
Final Words
Since you are having trouble finding Cozaar (losartan) in stock, it makes sense for your doctor to prescribe a different ARB drug for you.
There are many options to choose from and they all have similar effectiveness in lowering blood pressure (comparisons on other effects, such as a reduction in cardiovascular risk, is incomplete).
As shown above, it is important to remember that you can't quite compare the drugs on an mg-mg basis since they have different potencies.
References
- ^ Angiotensin II receptor blockers PubMed
- ^ Benicar Prescribing Information
- ^ Comparative efficacy of olmesartan, losartan, valsartan, and irbesartan in the control of essential hypertension. PubMed
- ^ Elsevier ClinicalKey Drug Class Overviews: Angiotensin Receptor Blockers (ARBs). ClinicalKey (Subscription Required)
- ^ In vitro and in vivo pharmacology of olmesartan medoxomil, an angiotensin II type AT1 receptor antagonist. PubMed
- ^ The Different Therapeutic Choices with ARBs. Which One to Give? When? Why? PubMed
