Diovan

Diovan (valsartan) is a drug that belongs to a class of drugs called angiotensin II receptor antagonists, also known as angiotensin II receptor blockers (ARBs). This drug is used to treat high blood pressure (hypertension), heart failure, and other cardiovascular conditions.

Valsartan works by blocking angiotensin II receptors in the vascular system. Angiotensin II is a substance that causes blood vessels to narrow and raise blood pressure. Blocking its action allows the blood vessels to widen, which reduces resistance to blood flow and allows the heart to pump blood more efficiently around the body, reducing pressure in the arteries.

Diovan is usually taken orally in tablet form. The dosage and regimen are determined by the doctor depending on the patient's condition and response to treatment. As with any medication, it is necessary to consult a doctor before using Diovan.

Indications Diovana

1. Hypertension (high blood pressure): Diovan is used to lower high blood pressure in patients with hypertension. High blood pressure can be a risk factor for developing cardiovascular diseases such as stroke and heart attacks.
2. Heart failure: Diovan may be prescribed as part of combination therapy to improve cardiac contractility, reduce symptoms and improve quality of life in patients with heart failure.
3. Post-infarction state: Valsartan may be prescribed in patients at high risk of cardiovascular complications after myocardial infarction to prevent recurrent cardiovascular events.
4. Diabetes mellitus with protein in urine: In patients with diabetes mellitus who have microalbuminuria (increased protein in the urine), Diovan can be used to slow the progression of the disease and prevent cardiovascular complications.
5. Prevention of cardiovascular complications: In some cases, Diovan may be prescribed to prevent cardiovascular complications in high-risk patients, such as those with risk factors including hypertension, diabetes, smoking, and others.

Release form

1. Tablets: This is the most common form of Diovan. Tablets come in different strengths, such as 40 mg, 80 mg, 160 mg or 320 mg.
2. Controlled-release tablets: Some manufacturers may produce Diovan as controlled-release tablets, which allows the drug to work longer and reduce the number of doses per day.
3. Combination tablets: Diovan may also be available as combination tablets containing valsartan and other antihypertensive drugs such as hydrochlorothiazide.
4. Powder for suspension: For children or people who have difficulty swallowing hard tablets, Diovan may be available as a powder for suspension.

Pharmacodynamics

1. AT1 receptor blocking: Valsartan binds with high affinity to angiotensin II receptors, specifically blocking them. This results in the prevention of the action of angiotensin II on these receptors.
2. Reduction in peripheral vascular resistance: Blockade of AT1 receptors by valsartan results in vasodilation and a reduction in peripheral resistance. This helps to reduce vascular resistance and lower blood pressure.
3. Decreasing Aldosterone Production: Valsartan may also decrease the production of aldosterone, a hormone that increases the reabsorption of sodium and water in the kidneys. This helps control blood volume and pressure.
4. Anti-remodeling action: Angiotensin II receptor antagonists, including valsartan, may have an anti-remodeling effect on the heart and blood vessels. This means that they may slow down or prevent negative changes in the structure and function of the heart and blood vessels, such as myocardial hypertrophy and fibrosis.
5. Antiarrhythmic action: Valsartan may have a beneficial effect on heart rhythm and prevent some types of arrhythmias.

Pharmacokinetics

1. Absorption: After oral administration of valsartan, it is rapidly and almost completely absorbed from the gastrointestinal tract. Food does not affect its absorption, so the drug can be taken regardless of food intake.
2. Maximum concentration (Cmax): The time to reach maximum plasma concentration is usually about 2-4 hours after taking valsartan.
3. Bioavailability: The oral bioavailability of valsartan is approximately 25-35% due to first pass metabolism through the liver.
4. Protein binding: Valsartan is highly bound to plasma proteins, mainly albumin (approximately 94-97%).
5. Metabolism: Valsartan is metabolized in the liver to form an active metabolite (valsartan acid metabolite). The major metabolite is 4-hydroxyvalsartan.
6. Elimination half-life (T½): The elimination half-life of valsartan from the body is about 6 hours, and its active metabolite is about 9 hours.
7. Excretion: Valsartan and its metabolite are excreted primarily via the kidneys in the urine and, to a lesser extent, via the intestines in the bile.
8. Metabolism Interactions: Valsartan may interact with other drugs, especially other antihypertensive drugs and drugs metabolized via the cytochrome P450 system.

Dosing and administration

Diovan (valsartan) is commonly used to treat hypertension. The standard starting and maintenance dose is 80 mg once daily. Depending on the patient's response to treatment, the dose may be increased to a maximum of 320 mg daily.

In a study involving patients with arterial hypertension living in the Far North, valsartan at a dosage of 160 mg per day was used for 4 weeks. Its effect on circadian changes in blood pressure, lipid, carbohydrate and water-salt metabolism was studied. Antihypertensive activity and tolerability of the drug were also analyzed, showing its effectiveness and good tolerability in this group of patients (Novokrestova et al., 2003).

The drug should be taken regardless of food intake, but it is recommended to take it at the same time every day to maintain a constant level of the drug in the blood. It is important to follow the recommended dosage and not exceed it without consulting a doctor.

Use Diovana during pregnancy

Use of valsartan (Diovan) during pregnancy is not recommended due to potential risk to the fetus, especially during the second and third trimesters of pregnancy. Valsartan belongs to a group of drugs called angiotensin II receptor inhibitors (ARBs), which may cause toxic effects on the fetus.

There is a documented case where the use of valsartan before the 20th week of pregnancy did not result in abnormalities in the fetus or the child after birth. However, this is an exception and in general such situations require caution and medical supervision (Öztürk, 2012).

In general, ARBs, including valsartan, may cause complications such as impaired renal function in the fetus, decreased amniotic fluid, and delayed skull development. Because of these risks, valsartan is not generally used during pregnancy unless absolutely necessary and there are no safer alternatives for treating hypertension.

Contraindications

1. Hypersensitivity: People with known hypersensitivity to valsartan or any of the components of the drug should avoid its use.
2. Pregnancy: Use of Diovan during pregnancy may be harmful to the fetus, especially in the second and third trimesters, and may result in birth defects.
3. Cardiogenic shock: Diovan is contraindicated in cardiogenic shock, a condition in which the heart is unable to pump enough blood to maintain normal circulation.
4. Severe renal impairment: The drug should be used with caution in patients with severe renal impairment.
5. Severe liver impairment: Diovan should be used with caution in patients with severe liver impairment.
6. Hypovolemia and/or hyponatremia: The drug should be used with caution in patients with hypovolemia (decreased circulating blood volume) and/or hyponatremia (low sodium levels in the blood).
7. Paediatric population: Use of Diovan in children requires special caution and should be carried out under medical supervision.
8. Use with other medications: Before using Diovan in combination with other medications, you should consult your doctor to ensure there are no potential interactions.

Side effects Diovana

1. Headache: One of the most common side effects of Diovan is headache or dizziness. These symptoms are usually temporary and may improve with continued treatment.
2. Hypotension: In some cases, Diovan may cause a drop in blood pressure, leading to hypotension (low blood pressure). This may manifest as a feeling of weakness, dizziness, or even loss of consciousness.
3. Fatigue and weakness: Some patients may feel tired or weak while taking Diovan.
4. Gastrointestinal disorders: These may include nausea, vomiting, diarrhea, and dyspepsia (indigestion).
5. Hyperkalemia: Diovan may increase potassium levels in the blood, especially in patients with impaired renal function or taking other medications that may increase potassium levels. This may cause cardiac arrhythmias and other cardiovascular complications.
6. Allergic reactions: Some people may experience allergic reactions to Diovan, such as skin rash, itching, swelling of the face or tongue.
7. Increased blood urea and creatinine: Diovan may cause increased blood urea and creatinine levels, which are indicators of impaired kidney function.
8. Other rare side effects: Include anemia, thrombocytopenia, increased liver enzymes, and others.

Overdose

1. Low blood pressure: Overdose of valsartan may cause a severe drop in blood pressure (hypotension), which may lead to dizziness, fainting, and serious complications such as cerebral ischemia or myocardial infarction in some patients.
2. Electrolyte imbalances: Overdose may cause an imbalance of electrolytes in the body, which may lead to hyperkalemia (high potassium in the blood), especially in patients with impaired renal function.
3. Drowsiness and central nervous system depression: Some patients may experience drowsiness, as well as impaired coordination, decreased activity, or even coma.
4. Other symptoms: Other symptoms of valsartan overdose may include headache, upset stomach, nausea, vomiting, and increased sensitivity to light.

Interactions with other drugs

1. Other antihypertensive drugs: Concomitant use of Diovan with other antihypertensive drugs such as diuretics, beta-blockers or ACE inhibitors may result in an increased hypotensive effect and an increased risk of hypotension.
2. Drugs that increase potassium levels: Diovan may increase the level of potassium in the blood. Therefore, taking Diovan with other drugs that may also increase potassium levels, such as potassium supplements or potassium-sparing diuretics, may lead to hyperkalemia.
3. Drugs that lower potassium levels: Using Diovan with drugs that may lower blood potassium levels, such as thiazide diuretics or laxatives, may reduce the effectiveness of blood pressure control and increase the risk of hypokalemia.
4. Nephrotoxic drugs: Using Diovan with nephrotoxic drugs, such as some nonsteroidal anti-inflammatory drugs (NSAIDs), antibiotics, or cancer drugs, may increase the risk of kidney damage.
5. Drugs metabolized via cytochrome P450: Valsartan may affect the metabolism of other drugs metabolized via the cytochrome P450 system in the liver, which may alter their effectiveness or blood levels.
6. Medicines that increase blood levels of valsartan: Some medicines, such as CYP2C9 inhibitors (eg, fluconazole), may increase blood levels of valsartan, which may increase its effect and increase the risk of side effects.