Olmesartan medoxomil is a prescription medication primarily used to manage high blood pressure, also known as hypertension. It is available under the brand name Benicar as well as in generic form. This drug belongs to a class of medications called angiotensin II receptor blockers, or ARBs. The medication works to reduce the risk of nonfatal and fatal cardiovascular events, such as strokes and heart attacks.
How Olmesartan Medoxomil Works
The function of olmesartan medoxomil is directly linked to the body’s renin-angiotensin-aldosterone system (RAAS), which helps regulate blood pressure. This system involves a protein called angiotensin II, a potent substance that causes blood vessels to constrict or narrow. Angiotensin II also stimulates the release of a hormone called aldosterone, which encourages the kidneys to retain sodium and water, further elevating blood pressure.
Olmesartan medoxomil is a prodrug, meaning it is converted into its active form, olmesartan, after being ingested. The active substance then works by selectively blocking AT1 receptors on the smooth muscle of blood vessels. By occupying these receptors, olmesartan prevents angiotensin II from binding to them and exerting its constricting effects. This is similar to a key being blocked from fitting into a lock, preventing the door from being opened.
This blockade of the AT1 receptors leads to the relaxation and widening of blood vessels. As a result, blood can flow more easily, which lowers overall blood pressure. Additionally, by inhibiting angiotensin II, the medication reduces the secretion of aldosterone, leading to decreased sodium and water retention by the kidneys. These combined physiological effects—vasodilation and reduced fluid volume—contribute to its effectiveness in managing hypertension.
Proper Usage and Dosage
Olmesartan is an oral tablet that is typically taken once per day. It is advisable to take it at the same time each day to maintain a consistent level of the medication. The tablet can be administered with or without food. A healthcare provider determines the appropriate dosage for each individual based on their specific condition and response to the treatment.
For adults, the usual starting dose is 20 mg once daily, which may be increased to 40 mg daily if blood pressure is not sufficiently controlled after two weeks. Individuals should continue taking it even if they feel well.
If a dose is missed, it should be taken as soon as it is remembered on the same day. However, if it is almost time for the next scheduled dose, the missed one should be skipped to avoid taking a double dose. Doubling the dose can increase the risk of unwanted side effects. Suddenly stopping the medication is not recommended, and any changes to the treatment plan should be discussed with a doctor.
Potential Side Effects
Like any medication, olmesartan medoxomil can cause side effects. It is helpful for individuals taking the drug to be aware of these potential effects and to know when to seek medical advice.
Common Side Effects
The most frequently reported side effect associated with olmesartan is dizziness or lightheadedness. This is particularly common when first starting the medication as the body adjusts to lower blood pressure. Other common effects can include back pain, flu-like symptoms, headache, and diarrhea. While these are generally mild, if they persist or become bothersome, it is a good idea to consult a healthcare provider.
Serious Side Effects
One significant concern is a condition called sprue-like enteropathy, which can cause severe, chronic diarrhea and substantial weight loss. These symptoms may develop months or even years after starting the drug and can be severe enough to require hospitalization. The condition involves intestinal damage, specifically villous atrophy, but it typically resolves after the medication is discontinued.
Signs of an allergic reaction are also considered serious. These can include hives, difficulty breathing, or swelling of the face, lips, tongue, or throat. Other serious effects include very low blood pressure (hypotension), kidney damage, and high potassium levels in the blood (hyperkalemia). If any of these severe symptoms occur, medical help should be sought immediately.
Important Warnings and Interactions
The U.S. Food and Drug Administration (FDA) has issued its most serious warning, a “black box warning,” for this medication due to its potential to cause harm to a developing fetus. Drugs that act on the renin-angiotensin system can cause injury or even death to a fetus, particularly when taken during the second and third trimesters of pregnancy. Olmesartan should be discontinued as soon as a pregnancy is detected. Individuals who are pregnant or planning to become pregnant should not take this medication.
Individuals with certain pre-existing health issues must use this medication with caution. This includes those with a history of kidney or liver disease, as well as those who are dehydrated or have low salt levels. The medication can worsen renal function in susceptible patients. Regular monitoring of kidney function and potassium levels is often recommended for these individuals.
Drug Interactions
Co-administration with nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen and naproxen, can reduce the blood pressure-lowering effect of olmesartan and increase the risk of kidney damage. Taking olmesartan with other drugs that can raise potassium levels, including potassium supplements and certain diuretics, may lead to hyperkalemia.
Combining olmesartan with lithium, a drug used to treat bipolar disorder, can increase lithium levels in the body, raising the risk of toxicity. Using it with other blood pressure medications can sometimes lead to an excessive drop in blood pressure, kidney problems, or high potassium. It is important to inform a healthcare provider of all prescription drugs, over-the-counter medicines, and supplements being taken.