VALSARTAN

VALSARTAN (val-sar'tan) Diovan Classifications: angiotensin ii receptor antagonist; antihypertensive; Therapeutic: antihypertensive; angiotensin ii receptor antagonist Prototype: Losartan Pregnancy Category: C first trimester; D second and third trimester

Availability

40 mg, 80 mg, 160 mg capsules

Action

An angiotensin II receptor (type AT₁) antagonist that blocks the angiotensin converting enzyme (ACE); it inhibits the binding of angiotensin II to the AT₁ receptors found in many tissues (e.g., vascular smooth muscle, adrenal glands). Angiotensin II is a potent vasoconstrictor and primary vasoactive hormone of the renin–angiotensin–aldosterone system.

Therapeutic Effect

Blocking the angiotensin II receptor results in vasodilation and blocking of the aldosterone-secreting effects of angiotensin II, thus resulting in an antihypertensive effect.

Uses

Treatment of hypertension, heart failure.

Contraindications

Hypersensitivity to valsartan or losartan; pregnancy [(category C) first trimester, (category D) second and third trimesters], lactation; severe heart failure with compromised renal function.

Cautious Use

Severe renal or hepatic impairment; renal artery stenosis; hypovolemia; congestive heart failure. Safety and efficacy in children <18 y are not established.

Route & Dosage

Hypertension Adult: PO 80 mg q.d. (max: 320 mg q.d.) Heart Failure Adult: PO Start with 40 mg b.i.d. and titrate up to 160 mg b.i.d. Hemodialysis: Adjustment not needed

Administration

Oral

• Give on an empty stomach.
• Correct volume depletion prior to initiation of therapy to prevent hypotension.
• Reduce dosage with severe hepatic or renal impairment.
• Note: Daily dose may be titrated up to 320 mg.
• Store at 15°–30° C (59°–86° F).

Adverse Effects (≥1%)

Body as a Whole: Arthralgia. CNS: Headache, dizziness. GI: Diarrhea, nausea. Respiratory: Cough, sinusitis. Metabolic: Hyperkalemia.

Pharmacokinetics

Absorption: Rapidly from GI tract, 25% bioavailability. Onset: Blood pressure decreased in 2 wk. Peak: Plasma levels, 2–4 h; blood pressure effect 4 wk. Distribution: 99% protein bound. Metabolism: In the liver. Elimination: Primarily in feces. Half-Life: 6 h.

Nursing Implications

Assessment & Drug Effects

• Monitor BP periodically; take trough readings, just prior to the next scheduled dose, when possible.
• Lab tests: Monitor liver function tests, BUN and creatinine, serum potassium, and CBC with differential, periodically.

Patient & Family Education

• Inform physician immediately if you become pregnant.
• Note: Maximum pressure lowering effect is usually evident between 2 and 4 wk after initiation of therapy.
• Notify physician of episodes of dizziness, especially those that occur when making position changes.

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Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug