Eprosartan: An Angiotensin II Receptor Blocker
Eprosartan is a medication that falls into the class of drugs known as angiotensin II receptor blockers (ARBs). It was previously marketed under the brand name Teveten and is also available in a combination product with the diuretic hydrochlorothiazide, called Teveten HCT. While effective, it's important to note that eprosartan was discontinued in the United States for business reasons, not due to safety or efficacy issues, and is no longer available there. However, it remains a notable drug in pharmacology and may be available in other regions. It is important for those who were previously prescribed this medication, or for students of pharmacology, to understand its therapeutic role.
How Eprosartan Works: The Mechanism of Action
Eprosartan's primary function is to interrupt the body's renin-angiotensin system (RAAS), a hormonal system that regulates blood pressure. Specifically, it acts as a competitive antagonist, selectively blocking the binding of angiotensin II to the AT1 receptor.
This blockade has several effects:
- Vascular Relaxation: Angiotensin II is a potent vasoconstrictor, meaning it causes blood vessels to constrict and narrow. By blocking this action, eprosartan allows blood vessels to relax and widen (vasodilation).
- Dual-Action Mechanism: Uniquely among some ARBs, eprosartan also blocks AT1 receptors located on sympathetic nerve endings (presynaptic receptors). This dual blockade inhibits the release of norepinephrine, further contributing to a reduction in blood pressure.
- Improved Blood Flow: The combined effect of relaxing blood vessels and inhibiting norepinephrine release allows blood to flow more smoothly and efficiently, decreasing the workload on the heart.
What Eprosartan Was Used For
The main therapeutic indication for eprosartan was the treatment of high blood pressure (hypertension). By effectively lowering blood pressure, the medication helps to mitigate long-term damage to the body's organs caused by uncontrolled hypertension. Regular use helps to reduce the risk of serious complications, including:
- Heart attacks
- Strokes
- Heart failure
- Kidney problems
In some clinical contexts, eprosartan was also used for other conditions:
- Heart Failure: For patients where the heart struggles to pump enough blood, eprosartan was sometimes used to help improve cardiac function.
- Diabetic Nephropathy: It has been used to manage kidney disease in patients with diabetes and high blood pressure.
- Combination Therapy: As mentioned, it was available as a combination pill with hydrochlorothiazide (Teveten HCT). This diuretic enhances the blood-pressure-lowering effect, making it effective for patients whose blood pressure wasn't adequately controlled with eprosartan alone.
Eprosartan vs. Other Angiotensin II Receptor Blockers
While most ARBs share the same fundamental function of blocking the AT1 receptor, eprosartan has some distinct properties. Here is a comparison with other common ARBs like losartan and valsartan.
| Feature | Eprosartan (Teveten) | Losartan (Cozaar) | Valsartan (Diovan) |
|---|---|---|---|
| Chemical Structure | Non-biphenyl, non-tetrazole | Biphenyl-tetrazole | Biphenyl-tetrazole |
| Receptor Antagonism | Pure competitive antagonist | Surmountable, produces active metabolite | Insurmountable antagonist |
| Mechanism | Dual blockade: AT1 receptor and presynaptic receptors | Primarily AT1 receptor blockade | Primarily AT1 receptor blockade |
| Elimination Half-Life | 5-9 hours (longer apparent half-life) | Shorter (requires twice-daily dosing) | Longer |
| PPAR-gamma Activation | Minimal | Lower potency than telmisartan | Lower potency than telmisartan |
| U.S. Availability | Discontinued | Yes | Yes |
Side Effects and Important Warnings
Like any medication, eprosartan could cause side effects. Most were mild to moderate, and generally better tolerated than the cough-inducing side effects of ACE inhibitors.
Common side effects included:
- Dizziness or lightheadedness
- Headache
- Stomach pain
- Joint pain
- Excessive tiredness
- Congestion or sore throat
Serious, but rare, side effects that required immediate medical attention included:
- Swelling of the face, throat, or tongue (angioedema)
- Difficulty breathing
- High potassium levels (symptoms like muscle weakness or irregular heartbeat)
- Severe kidney problems or acute renal failure
It was strictly contraindicated for women during the second and third trimesters of pregnancy due to the risk of injury and death to the fetus. Patients with diabetes taking aliskiren should also avoid eprosartan.
Administration
Eprosartan was typically taken once daily or divided into two doses. Taking it twice daily could sometimes provide a more satisfactory response for some patients. The medication could be taken with or without food. Full therapeutic benefits might not be achieved for 2 to 3 weeks.
Conclusion
Eprosartan was an effective and well-tolerated angiotensin II receptor blocker used for the management of high blood pressure and other related cardiovascular conditions. Its unique dual-action mechanism and competitive antagonism set it apart from other ARBs. While it is no longer available in some markets, understanding its pharmacological profile provides valuable insight into the treatment options for hypertension and the broader class of ARB medications. For patients requiring an antihypertensive, several other effective ARB options are available and widely prescribed, and a healthcare provider can determine the best alternative.
For more in-depth information, the full FDA Prescribing Information for Teveten provides extensive details on clinical pharmacology and studies.
