irbesartan

irbesartan

(er bah sar' tan)

Avapro

Pregnancy Category C (first trimester)

Pregnancy Category D (second and third trimesters)

Drug classes

Angiotensin II receptor antagonist (ARB)

Antihypertensive

Therapeutic actions

Selectively blocks the binding of angiotensin II to specific tissue receptors found in the vascular smooth muscle and adrenal gland; this action blocks the vasoconstriction effect of the renin-angiotensin system as well as the release of aldosterone, leading to decreased BP.

Indications

·        Treatment of hypertension as monotherapy or in combination with other antihypertensives

·        Slowing of the progression of nephropathy in patients with hypertension and type 2 (non–insulin-dependent) diabetes

·        Unlabeled use: CHF

Contraindications and cautions

·        Contraindicated with hypersensitivity to irbesartan, pregnancy (use during the second or third trimester can cause injury or even death to the fetus).

·        Use cautiously with hepatic or renal dysfunction, hypovolemia, lactation, pregnancy.

Available forms

Tablets—75, 150, 300 mg

Dosages

ADULTS

·        Diabetic neuropathy: 300 mg/day PO as a single dose.

·        Hypertension: 150 mg PO daily as one dose; adjust slowly to determine effective dose; maximum daily dose—300 mg.

PEDIATRIC PATIENTS 13-16 YR

150 mg/day PO; maximum dose, 300 mg.

PEDIATRIC PATIENTS 6–12 YR

75 mg/day PO, titrate to a maximum of 150 mg/day.

PEDIATRIC PATIENTS < 6 YR

Not recommended.

VOLUME- OR SALT-DEPLETED PATIENTS

75 mg/day PO.

Pharmacokinetics

Route	Onset	Peak
Oral	Varies	1–3 hr

Metabolism: Hepatic; T_1/2: 11–15 hr

Distribution: Crosses placenta; enters breast milk

Excretion: Feces, urine

Adverse effects

·        CNS: Headache, dizziness, syncope, muscle weakness, sleep disturbance

·        CV: Hypotension, orthostatic hypotension, flushing

·        Dermatologic: Rash, inflammation, urticaria, pruritus, alopecia, dry skin

·        GI: Diarrhea, abdominal pain, nausea, constipation, dry mouth, dental pain

·        Respiratory: URI symptoms, cough, sinus disorders

·        Other: Cancer in preclinical studies, back pain, fever, gout, fatigue, neutropenia, angioedema

Interactions

Drug-drug

·        Use caution with drugs metabolized by CYP2C9; anticipated effects may be altered.

Nursing considerations

Assessment

·        History: Hypersensitivity to irbesartan, pregnancy, lactation, hepatic or renal dysfunction, hypovolemia

·        Physical: Skin lesions, turgor; T; reflexes, affect; BP; R, respiratory auscultation; LFTs, renal function tests

Interventions

·        Administer without regard to meals.

·        WARNING: Ensure that patient is not pregnant before beginning therapy; suggest using barrier birth control while using irbesartan; fetal injury and deaths have been reported.

·        Find an alternative method of feeding the baby if giving drug to a nursing mother. Depression of the renin-angiotensin system in infants is potentially very dangerous.

·        WARNING: Alert surgeon and mark patient's chart with notice that irbesartan is being taken. The blockage of the renin-angiotensin system following surgery can produce problems. Hypotension may be reversed with volume expansion.

·        Monitor patient closely in any situation that may lead to a decrease in BP secondary to reduction in fluid volume (excessive perspiration, dehydration, vomiting, diarrhea); excessive hypotension can occur.

Teaching points

·        Take this drug without regard to meals. Do not stop taking this drug without consulting your health care provider.

·        Use a barrier method of birth control while using this drug; if you become pregnant or desire to become pregnant, consult your health care provider.

·        You may experience these side effects: Dizziness (more likely to occur in any situation where you may be fluid depleted [extreme heat, exertion]; avoid driving or performing hazardous tasks); headache (medications may be available to help); nausea, vomiting, diarrhea (proper nutrition is important; consult a dietitian); symptoms of upper respiratory tract infection, cough (do not self-medicate; consult your health care provider if this becomes uncomfortable).

·        Report fever, chills, dizziness, pregnancy.

Adverse effects in Italic are most common; those in Bold are life-threatening.