Valsartan

Pronunciation: val-SAR-tan
Class: Angiotensin II receptor antagonist

Trade Names

Diovan
- Tablets 40 mg
- Tablets 80 mg
- Tablets 160 mg
- Tablets 320 mg

Pharmacology

Antagonizes the effect of angiotensin II (vasoconstriction and aldosterone secretion) by blocking the binding of angiotensin II to the AT ₁ receptor in vascular smooth muscle and the adrenal gland, producing decreased BP.

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Pharmacokinetics

Absorption

T _max is 2 to 4 h after dosing. Bioavailability is about 10% to 35%. Food decreases AUC about 40% and decreases C _max about 50%.

Distribution

Vd is about 17 L. Highly bound to albumin (about 95%).

Metabolism

The major metabolite, valeryl 4-hydroxy valsartan, accounts for about 9% of the dose.

Elimination

Half-life is about 6 h. Valsartan is primarily recovered in the feces (about 83%) and urine (about 13%). Recovery is mainly unchanged drug, with only about 20% of the dose recovered as metabolite. The plasma Cl is about 2 L/h.

Special Populations

No correlation between renal function and exposure to the drug.

Patients with mild to moderate chronic liver disease have about twice the AUC value.

AUC is about 70% higher and t _½ is about 35% longer in elderly patients.

Indications and Usage

Treatment of hypertension; treatment of heart failure; reduction of CV mortality in clinically stable patients with left ventricular failure or dysfunction after MI.

Contraindications

Standard considerations.

Dosage and Administration

PO Initial dosage: 80 or 160 mg once daily. Maintenance dosage: 80 to 320 mg once daily.

PO Initial dosage: 1.3 mg/kg (up to 40 mg) once daily. Adjust dose based on BP response. Dosages higher than 2.7 mg/kg (up to 160 mg) once daily have not been studied in children.

PO Initial dosage: 40 mg twice daily; titration to 80 and 160 mg twice daily should be done to the highest dose, as tolerated by the patient (max dose, 320 mg/day).

PO Initiate 12 h after MI at 20 mg twice daily. Titrate within 7 days to 40 mg twice daily with additional titrations to a target maintenance dosage of 160 mg twice daily, as tolerated by the patient.

Exercise care with dosing in patients with hepatic or severe renal function impairment.

General Advice

May be administered with or without food.

Storage/Stability

Store at 59° to 86°F in tightly closed container. Protect from moisture.

Drug Interactions

May increase valsartan plasma concentrations.

Plasma concentrations may be increased by valsartan, resulting in an increase in the pharmacologic and adverse reactions of lithium.

Coadministration may cause elevated serum potassium concentrations in certain high-risk patients.

Laboratory Test Interactions

None well documented.

Adverse Reactions

Cardiovascular

Hypotension (7%); postural hypotension (2%); syncope (at least 1%).

CNS

Dizziness (17%); fatigue (3%); postural dizziness (2%); headache, vertigo (at least 1%).

Dermatologic

Alopecia (postmarketing).

EENT

Blurred vision (at least 1%).

GI

Diarrhea (5%); abdominal pain (2%); nausea, upper abdominal pain (at least 1%).

Genitourinary

Renal function impairment (at least 1%).

Hematologic-Lymphatic

Thrombocytopenia (postmarketing).

Hepatic

Elevated liver enzymes, hepatitis (postmarketing).

Metabolic-Nutritional

Hyperkalemia (2%).

Musculoskeletal

Arthralgia, back pain (3%); rhabdomyolysis (postmarketing).

Respiratory

Dry cough (3%).

Miscellaneous

Viral infection (3%); hypersensitivity (postmarketing).

Precautions

Pregnancy

Category D .

Lactation

Undetermined.

Children

Safety and efficacy not established in children younger than 6 yr of age.

Use caution when initiating therapy; hypotension may occur.

Renal Function

Patients with renal artery stenosis may experience acute renal failure. Use caution in treating patients whose renal function may depend on the activity of renin-angiotensin-aldosterone system (eg, severe CHF).

Hepatic Function

Use with caution.

Hypotension/Volume-depleted patients

Symptomatic hypotension may occur after initiation of valsartan therapy in patients who are intravascularly volume depleted (eg, those treated with diuretics). Correct these conditions prior to administration of valsartan or start treatment under close medical supervision.

Overdosage

Symptoms

Bradycardia, hypotension, tachycardia.

Patient Information

• Instruct patient to take medication as prescribed at same time each day.
• Inform patients that valsartan controls but does not cure hypertension.
• Caution patients to take dose exactly as prescribed and not to stop taking medication even if feeling better. Instruct patient not to decrease or increase dosage.
• Instruct the patient in BP- and pulse-measuring skills. Advise patient to call health care provider if abnormal readings occur.
• Instruct patients in methods of fall prevention, including arising slowly and sitting on side of bed before standing, especially early in therapy.
• Inform patients of importance of adjunctive therapies such as dietary planning, a regular exercise program, weight reduction, a low-sodium diet, smoking cessation program, alcohol reduction, and stress management.
• Instruct patient to report the following symptoms to health care provider: changes in urinary output, discomfort during urination, dizziness, fatigue, jaundice, light-headedness, weakness.
• Emphasize importance of follow-up visits and frequent assessment of BP while taking drug.
• Instruct patients to avoid use of supplements or salt substitutes containing potassium without consulting health care provider first.

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