The ARBs act by selectively binding to and blocking the angiotensin II type 1 (AT1) receptor. Virtually all known deleterious responses to angiotensin II, the main effector peptide of the RAAS (Renin Angiotensin Aldosterone System), are mediated through the AT1 receptor. Such responses include vasoconstriction, aldosterone and vasopressin secretion, sympathetic nervous system activation, renal tubular sodium reabsorption, and decreased renal blood flow. Chronic AT1 receptor stimulation also contributes independently to such diseases as vascular smooth-muscle cell growth and proliferation, left ventricular hypertrophy (LVH), glomerulosclerosis, vascular media hypertrophy, endothelial dysfunction, neointima formation, atherosclerosis, stroke, and dementia.
The pharmacologic basis for interrupting the RAAS with ARB therapy is threefold:
(1) Selective AT1 blockade with an ARB inhibits the negative cardiovascular consequences of AT1 receptor activation.
(2) Circulating angiotensin II (the levels of which undergo a compensatory rise during ARB therapy) can act only at unopposed AT2 receptors. This should preserve (or even augment) the favorable effects of angiotensin II, potentially producing benefits above and beyond those due to blood pressure control.
(3) Because they act at the final step of the RAAS, ARBs block the effects of angiotensin II regardless of whether it is generated systemically by ACE or within tissues by ACE-independent pathways.
What is Olmesartan?
• Olmesartan is in a class of drugs called angiotensin II receptor antagonists. Olmesartan prevents the constriction (narrowing) of blood vessels (veins and arteries).
• Olmesartan is used to treat hypertension (high blood pressure).
• Olmesartan may also be used for purposes other than those listed in PDR
Benicar Pronounced: BEN-ick-ar Generic name: Olmesartan medoxomil
Why is this drug prescribed? Return to top Benicar controls high blood pressure. It works by blocking the effect of a hormone called angiotensin II. Unopposed, this substance prompts the blood vessels to contract, an action that tends to raise blood pressure. Benicar relaxes and expands the blood vessels, allowing pressure to drop. The drug may be prescribed alone or with other blood pressure medications. Most important fact about this drug Return to top You must take Benicar regularly for it to be effective. Since blood pressure declines gradually, it may be a couple of weeks before you get significant benefits from Benicar, and you must continue taking it even though you feel well. Benicar does not cure high blood pressure; it merely keeps it under control. How should you take this medication? Return to top Benicar should be taken once a day, preferably at the same time each day. It can be taken with or without food. --If you miss a dose... Take it as soon as you remember. If it's almost time for your next dose, skip the one you missed and go back to your regular schedule. Do not take two doses in the same day. --Storage instructions... Store at room temperature. What side effects may occur? Return to top Side effects cannot be anticipated. If any develop or change in intensity, inform your doctor as soon as possible. Only your doctor can determine if it is safe for you to continue taking Benicar. · The most common side effect is: Dizziness · Less common side effects may include: Back pain, blood in urine, bronchitis, diarrhea, flu-like symptoms, headache, high blood sugar, injury, runny nose, sinus inflammation, sore throat, upper respiratory tract infection · Rare side effects may include: Abdominal pain, bone pain, chest pain, cough, fast heartbeat, fatigue, indigestion, insomnia, joint pain or inflammation, muscle pain, nausea, rash, stomach problems, swelling of the face or limbs, urinary tract infection, vertigo Why should this drug not be prescribed? Return to top If you have an allergic reaction to Benicar, you'll be unable to use it. Special warnings about this medication Return to top Benicar can cause a severe drop in blood pressure, especially when you first start taking the drug. The problem is more likely to occur if your body's supply of water has been depleted by diuretics (water pills). Symptoms include light-headedness, dizziness, and faintness. If you develop this problem, lie down and contact your physician. You may need to have your dose adjusted. If you have kidney disease or congestive heart failure, Benicar must be used with caution. In people with these problems, Benicar has been known to impair kidney function or even lead to kidney failure. Possible food and drug interactions when taking this medication Return to top No significant drug interactions have been reported. Special information if you are pregnant or breastfeeding Return to top Benicar can cause injury or death to a developing baby when used during the last six months of pregnancy. As soon as you learn you are pregnant, stop taking Benicar and call your doctor. It is not known whether Benicar appears in breast milk, but because of the potential risks to the nursing infant, it's best to avoid the drug while breastfeeding Recommended dosage Return to top ADULTS The usual starting dose is 20 milligrams once daily. If your blood pressure hasn't dropped sufficiently after 2 weeks, the doctor may raise the dose to 40 milligrams once a day. If you are taking a diuretic, your starting dose may be smaller than usual. Overdosage Return to top Any medication taken in excess can have serious consequences. If you suspect an overdose, seek medical attention immediately. · Symptoms of Benicar overdose may include: Fast or slow heartbeat, very low blood pressure