enalapril maleate

enalapril maleate

(e nal' a pril)

Vasotec

enalaprilat

Vasotec I.V.

Pregnancy Category D

Drug classes

Antihypertensive

ACE inhibitor

Therapeutic actions

Renin, synthesized by the kidneys, is released into the circulation where it acts on a plasma precursor to produce angiotensin I, which is converted by ACE toangiotensin II, a potent vasoconstrictor that also causes release of aldosterone from the adrenals; both of these actions increase BP. Enalapril blocks the conversion of angiotensin I to angiotensin II, decreasing BP, decreasing aldosterone secretion, slightly increasing serum K⁺ levels, and causing Na⁺ and fluid loss; increased prostaglandin synthesis also may be involved in the antihypertensive action. In patients with heart failure, peripheral resistance, afterload, preload, and heart size are decreased.

Indications

·        Treatment of hypertension alone or in combination with other antihypertensives, especially thiazide-type diuretics

·        Treatment of acute and chronic CHF

·        Treatment of asymptomatic left ventricular dysfunction (LVD)

·        Unlabeled use: Diabetic nephropathy

Contraindications and cautions

·        Contraindicated with allergy to enalapril.

·        Use cautiously with impaired renal function; salt or volume depletion (hypotension may occur); lactation, pregnancy.

Available forms

Tablets—2.5, 5, 10, 20 mg; injection—1.25 mg/mL

Dosages

ADULTS

Oral

·        Hypertension:
Patients not taking diuretics: Initial dose is 5 mg/day PO. Adjust dosage based on patient response. Usual range is 10–40 mg/day as a single dose or in two divided doses.
Patients taking diuretics: Discontinue diuretic for 2–3 days if possible. If it is not possible to discontinue diuretic, give initial dose of 2.5 mg, and monitor for excessive hypotension.
Converting to oral therapy from IV therapy: 5 mg daily with subsequent doses based on patient response.

·        Heart failure: 2.5 mg PO daily or bid in conjunction with diuretics and digitalis. Maintenance dose is 5–20 mg/day given in two divided doses. Maximum daily dose is 40 mg.

·        Asymptomatic LVD: 2.5 mg PO bid; target maintenance dose 20 mg/day in two divided doses.

Parenteral

Give IV only. 1.25 mg q 6 hr given IV over 5 min. A response is usually seen within 15 min, but peak effects may not occur for 4 hr.

·        Hypertension:
Converting to IV therapy from oral therapy: 1.25 mg q 6 hr; monitor patient response.

·        Patients taking diuretics: 0.625 mg IV over 5 min. If adequate response is not seen after 1 hr, repeat the 0.625-mg dose. Give additional doses of 1.25 mg q 6 hr.

PEDIATRIC PATIENTS 1 MO–16 YR

Oral

·        Hypertension: Initial dose is 0.08 mg/kg PO once daily; maximum dose is 5 mg.

GERIATRIC PATIENTS AND PATIENTS WITH RENAL IMPAIRMENT

Oral

Excretion is reduced in renal failure; use smaller initial dose, and adjust upward to a maximum of 40 mg/day PO. For patients on dialysis, use 2.5 mg on dialysis days.

Creatinine Clearance (mL/min)	Serum Creatinine	Initial Dose
> 80	Not applicable	5 mg/day
< 80– > 30	< 3 mg/dL	5 mg/day
< 30	> 3 mg/dL	2.5 mg/day

IV

If creatinine clearance 30 mL/min, the initial dose is 0.625 mg, which may be repeated. Additional doses of 1.25 mg q 6 hr may be given with careful patient monitoring.

Pharmacokinetics

Route	Onset	Peak	Duration
Oral	60 min	4–6 hr	24 hr
IV	15 min	1–4 hr	6 hr

Metabolism: T_1/2: 11 hr

Distribution: Crosses placenta; enters breast milk

Excretion: Urine

IV facts

Preparation: Enalaprilat can be given as supplied or mixed with up to 50 mL of 5% dextrose injection, 0.9% sodium chloride injection, 0.9% sodium chloride injection in 5% dextrose, 5% dextrose in lactated Ringer's, Isolyte E. Stable at room temperature for 24 hr.

Infusion: Give by slow IV infusion over at least 5 min.

Adverse effects

·        CNS: Headache, dizziness, fatigue, insomnia, paresthesias

·        CV: Syncope, chest pain, palpitations, hypotension in salt- or volume-depleted patients

·        GI: Gastric irritation, nausea, vomiting, diarrhea, abdominal pain, dyspepsia, elevated liver enzymes

·        GU: Proteinuria, renal insufficiency, renal failure, polyuria, oliguria, urinary frequency, impotence

·        Hematologic: Decreased Hct and Hgb

·        Other: Cough, muscle cramps, hyperhidrosis

Interactions

Drug-drug

·        Decreased hypotensive effect if taken concurrently with indomethacin, rifampin

Nursing considerations

Assessment

·        History: Allergy to enalapril, impaired renal function, salt or volume depletion, lactation, pregnancy

·        Physical: Skin color, lesions, turgor; T; orientation, reflexes, affect, peripheral sensation; P, BP, peripheral perfusion; mucous membranes, bowel sounds, liver evaluation; urinalysis, LFTs, renal function tests, CBC, and differential

Interventions

·        WARNING: Alert surgeon, and mark patient's chart with notice that enalapril is being taken; the angiotensin II formation subsequent to compensatory reninrelease during surgery will be blocked; hypotension may be reversed with volume expansion.

·        Monitor patients on diuretic therapy for excessive hypotension after the first few doses of enalapril.

·        Monitor patient closely in any situation that may lead to a drop in BP secondary to reduced fluid volume (excessive perspiration and dehydration, vomiting, diarrhea) because excessive hypotension may occur.

·        Arrange for reduced dosage in patients with impaired renal function.

·        WARNING: Monitor patient carefully because peak effect may not be seen for 4 hr. Do not administer second dose until BP has been checked.

Teaching points

·        Do not stop taking the medication without consulting your health care provider.

·        Be careful in any situation that may lead to a drop in blood pressure (diarrhea, sweating, vomiting, dehydration).

·        Avoid over-the-counter medications, especially cough, cold, and allergy medications that may interact with this drug.

·        You may experience these side effects: GI upset, loss of appetite, change in taste perception (will pass with time); mouth sores (frequent mouth care may help); rash; fast heart rate; dizziness, light-headedness (usually passes in a few days; change position slowly, limit activities to those not requiring alertness and precision).

·        Report mouth sores; sore throat, fever, chills; swelling of the hands, feet; irregular heartbeat, chest pains; swelling of the face, eyes, lips, tongue, difficulty breathing.

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