DESCRIPTION
Olmesartan -Olmesartan is an antihypertensive agent, which belongs to the class of medications called angiotensin II receptor blockers. It is indicated for the treatment of high blood pressure and is marketed under the name Olmetec®. The FDA label includes a black-box warning of injury and death to the fetus, so women of child-bearing age need to be warned and take the necessary precautions. Olmesartan is also contraindicated in diabetes mellitus patients taking aliskiren.Amlodipine -Amlodipine is a long-acting 1,4-dihydropyridine calcium channel blocker. It acts primarily on vascular smooth muscle cells by stabilizing voltage-gated L-type calcium channels in their inactive conformation. By inhibiting the influx of calcium in smooth muscle cells, amlodipine prevents calcium-dependent myocyte contraction and vasoconstriction. A second proposed
MECHANISM
for the drug’s vasodilatory effects involves pH-dependent inhibition of calcium influx via inhibition of smooth muscle carbonic anhydrase. Some studies have shown that amlodipine also exerts inhibitory effects on voltage-gated N-type calcium channels. N-type calcium channels located in the central nervous system may be involved in nociceptive signaling and pain sensation. Amlodipine is used to treat hypertension and chronic stable angina.Antihypertensive Agents Vasodilator Agents,Calcium Channel Blockers,Antianginal Agents. Hydrochlorthiazide-A thiazide diuretic often considered the prototypical member of this class. It reduces the reabsorption of electrolytes from the renal tubules. This results in increased excretion of water and electrolytes, including sodium, potassium, chloride, and magnesium. It has been used in the treatment of several disorders including edema, hypertension, diabetes insipidus, and hypoparathyroidism.
CATEGORIES
Olmesartan -Angiotensin II Type 1 Receptor Blockers.Amlodipine -Antihypertensive Agents,Vasodilator Agents,Calcium Channel Blockers,Antianginal Agents.Hydrochlorthiazide-Antihypertensive Agents Diuretics,Sodium Chloride Symporter Inhibitors.
CHEMICAL FORMULA
Olmesartan -C24H26N6O3.Amlodipine -C20H25ClN2O5. Hydrochlorthiazide-C7H8ClN3O4S2.
COMPOSITION
Olmesartan 20 Mg + Amlodipine 5 Mg + Hydrochlorthiazide 25 Mg
INDICATION
Olmesartan -For the treatment of hypertension.Amlodipine -For the treatment of hypertension and chronic stable angina. Hydrochlorthiazide-For the treatment of high blood pressure and management of edema.
PHARMACODYNAMICS
Olmesartan -Olmesartan is a specific angiotensin II type 1 (AT1) receptor antagonist, which blocks the blood pressure increasing effects of angiotensin II via the renin-angiotensin-aldosterone system (RAAS). During sympathetic stimulation or when renal blood pressure or blood flow is reduced, renin is released from granular cells of the juxtaglomerular apparatus in the kidneys. Renin cleaves circulating angiotensinogen to angiotensin I, which is cleaved by angiotensin converting enzyme (ACE) to angiotensin II. Angiotensin II increases blood pressure by increasing total peripheral resistance, increasing sodium and water reabsorption in the kidneys via aldosterone secretion, and altering cardiovascular structure. Angiotensin II binds to two receptors: AT1 and AT2. AT1 is a G-protein coupled receptor (GPCR) that mediates the vasoconstrictive and aldosterone-secreting effects of angiotensin II. Angiotensin receptor blockers (ARBs) are non-peptide competitive inhibitors of AT1. ARBs block the ability of angiotensin II to stimulate pressor and cell proliferative effects. Unlike ACE inhibitors, ARBs do not affect bradykinin-induced vasodilation. The overall effect of ARBs is a decrease in blood pressure. Amlodipine -Amlodipine belongs to the dihydropyridine (DHP) class of calcium channel blockers (CCBs), the most widely used class of CCBs. There are at least five different types of calcium channels in Homo sapiens: L-, N-, P/Q-, R- and T-type. It was widely accepted that DHP CCBs target L-type calcium channels, the major channel in muscle cells that mediate contraction; however, some studies have indicated that amlodipine also binds to and inhibits N-type calcium channels (see references in Targets section). Similar to other DHP CCBs, amlodipine binds directly to inactive L-type calcium channels stabilizing their inactive conformation. Since arterial smooth muscle depolarizations are longer in duration than cardiac muscle depolarizations, inactive channels are more prevalent in smooth muscle cells. Alternative splicing of the alpha-1 subunit of the channel gives amlodipine additional arterial selectivity. At therapeutic sub-toxic concentrations, amlodipine has little effect on cardiac myocytes and conduction cells.Hydrochlorthiazide-Thiazides such as hydrochlorothiazide promote water loss from the body (diuretics). They inhibit Na+/Cl- reabsorption from the distal convoluted tubules in the kidneys. Thiazides also cause loss of potassium and an increase in serum uric acid. Thiazides are often used to treat hypertension, but their hypotensive effects are not necessarily due to their diuretic activity. Thiazides have been shown to prevent hypertension-related morbidity and mortality although the
MECHANISM
is not fully understood. Thiazides cause vasodilation by activating calcium-activated potassium channels (large conductance) in vascular smooth muscles and inhibiting various carbonic anhydrases in vascular tissue.
No Information
ABSORPTION
Olmesartan -Bioavailability is about 26%. Food does not affect the bioavailability of olmesartan.Amlodipine -Amlodipine is slowly and almost completely absorbed from the gastrointestinal tract. Peak plasma concentrations are reached 6-12 hour following oral administration. Its estimated bioavailability is 64-90%. Absorption is not affected by food. Hydrochlorthiazide-50-60%.
VOLUME DISTRIBUTION
Olmesartan -The volume of distribution is 17 L and olmesartan poorly crosses the blood brain barrier.
METABOLISM
Olmesartan -Olmesartan is rapidly and completely bioactivated by ester hydrolysis to olmesartan during absorption from the gastrointestinal tract. There is virtually no further metabolism of olmesartan.Amlodipine -Hepatic. Metabolized extensively (90%) to inactive metabolites via the cytochrome P450 3A4 isozyme.Hydrochlorthiazide-Hydrochlorothiazide is not metabolized.
ELIMINATION
Olmesartan -Olmesartan is elminated unchanged in the urine (35% to 50%) and the remainder in the feces.Amlodipine -Amlodipine is extensively (about 90%) converted to inactive metabolites via hepatic metabolism with 10% of the parent compound and 60% of the metabolites excreted in the urine. Hydrochlorthiazide-Hydrochlorothiazide is not metabolized but is eliminated rapidly by the kidney. Hydrochlorothiazide crosses the placental but not the blood-brain barrier and is excreted in breast milk.
HALF LIFE
Olmesartan -The half life is approximately 13 hours.Amlodipine -30-50 hours.Hydrochlorthiazide-5.6 and 14.8 hours
TOXICITY
Olmesartan -The main symptoms of overdose include low blood pressure and fast heartbeat.Amlodipine -Gross overdosage could result in excessive peripheral vasodilatation and possibly reflex tachycardia. Marked and probably prolonged systemic hypotension up to an including shock with fatal outcome have been reported.Hydrochlorthiazide-The most common signs and symptoms observed are those caused by electrolyte depletion (hypokalemia, hypochloremia, hyponatremia) and dehydration resulting from excessive diuresis. If digitalis has also been administered, hypokalemia may accentuate cardiac arrhythmias. The oral LD50 of hydrochlorothiazide is greater than 10 g/kg in the mouse and rat.
FOOD INTERACTIONS
Olmesartan -Food does not affect the bioavailability of olmesartan.Amlodipine -Avoid natural licorice. Grapefruit down regulates post-translational expression of CYP3A4, the major metabolizing enzyme of amlodipine. Grapefruit, in all forms (e.g. whole fruit, juice and rind), can significantly increase serum levels of amlodipine and may cause toxicity. Avoid grapefruit products while on this medication. Take without regard to meals.Hydrochlorthiazide-Avoid alcohol. Avoid excess salt/sodium unless otherwise instructed by your physician. Avoid natural licorice. Do not take calcium, aluminum, magnesium or Iron supplements within 2 hours of taking this medication. Increase potassium intake; add a banana or orange juice; unless instructed otherwise. Take with food.
SIDE EFFECTS
Olmesartan -Feeling dizzy. Rise slowly over a few minutes when sitting or lying down. Be careful climbing. Cough. Loose stools (diarrhea). High potassium level. Signs include feeling weak, lightheaded, dizzy, feel like passing out, or have numbness or tingling. Kidney function that gets worse.Amlodipine -Feeling dizzy. Rise slowly over a few minutes when sitting or lying down. Be careful while climbing. – Headache. – Hard stools (constipation). Drinking more liquids, working out, or adding fiber to your diet may help. – Talk with your doctor about a stool softener or laxative. – Swelling in the arms or legs .