Captopril

captopril

(kap' toe pril)

Apo-Capto (CAN), Capoten, Gen-Captopril (CAN), Novo-Captopril (CAN), Nu-Capto (CAN)

Pregnancy Category C (first trimester)

Pregnancy Category D (second, third trimesters)

Drug classes

ACE inhibitor

Antihypertensive

Therapeutic actions

Blocks ACE from converting angiotensin I to angiotensin II, a powerful vasoconstrictor, leading to decreased BP, decreased aldosterone secretion, a small increase in serum potassium levels, and sodium and fluid loss; increased prostaglandin synthesis also may be involved in the antihypertensive action.

Indications

·        Treatment of hypertension alone or in combination with thiazide-type diuretics

·        Treatment of CHF in patients unresponsive to conventional therapy; used with diuretics and digitalis

·        Treatment of diabetic nephropathy

·        Treatment of left ventricular dysfunction after MI

·        Unlabeled uses: Management of hypertensive crises; treatment of rheumatoid arthritis; diagnosis of anatomic renal artery stenosis, hypertension related to scleroderma renal crisis; diagnosis of primary aldosteronism, idiopathic edema; Bartter's syndrome; Raynaud's syndrome

Contraindications and cautions

·        Contraindicated with allergy to captopril, history of angiodema, second or third trimester of pregnancy.

·        Use cautiously with impaired renal function; CHF; salt or volume depletion, lactation.

Available forms

Tablets—12.5, 25, 50, 100 mg

Dosages

ADULTS

·        Hypertension: 25 mg PO bid or tid; if satisfactory response is not noted within 1–2 wk, increase dosage to 50 mg bid–tid; usual range is 25–150 mg bid–tid PO with a mild thiazide diuretic. Do not exceed 450 mg/day.

·        CHF: 6.25–12.5 mg PO tid in patients who may be salt or volume depleted. Usual initial dose, 25 mg PO tid; maintenance dose, 50–100 mg PO tid. Do not exceed 450 mg/day. Use in conjunction with diuretic and digitalis therapy.

·        Left ventricular dysfunction after MI: 50 mg PO tid, starting as early as 3 days post-MI. Initial dose of 6.25 mg, then 12.5 mg tid, increasing slowly to 50 mg tid.

·        Diabetic nephropathy: 25 mg PO tid.

PEDIATRIC PATIENTS

Safety and efficacy not established.

GERIATRIC PATIENTS AND PATIENTS WITH RENAL IMPAIRMENT

Excretion is reduced in renal failure; use smaller initial dose; adjust at smaller doses with 1- to 2-wk intervals between increases; slowly adjust to smallest effective dose. Use a loop diuretic with renal dysfunction.

Pharmacokinetics

Route	Onset	Peak
Oral	15 min	30–90 min

Metabolism: T_1/2: 2 hr

Distribution: Crosses placenta; enters breast milk

Excretion: Urine

Adverse effects

·        CV: Tachycardia, angina pectoris, MI, Raynaud's syndrome, CHF, hypotension in salt- or volume-depleted patients

·        Dermatologic: Rash, pruritus, scalded mouth sensation, pemphigoid-like reaction, exfoliative dermatitis, alopecia, photosensitivity

·        GI: Gastric irritation, aphthous ulcers, peptic ulcers, dysgeusia, cholestatic jaundice, hepatocellular injury, anorexia, constipation

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

·        Hematologic: Neutropenia, agranulocytosis, thrombocytopenia, hemolytic anemia, pancytopenia

·        Other: Cough, malaise, dry mouth, lymphadenopathy

Interactions

Drug-drug

·        Increased risk of hypersensitivity reactions with allopurinol

·        Decreased antihypertensive effects with indomethacin

·        Increased captopril effects with probenecid

Drug-food

·        Decreased absorption of captopril with food

Drug-lab test

·        False-positive test for urine acetone

Nursing considerations

Assessment

·        History: Allergy to captopril, history of angioedema, impaired renal function, CHF, salt or volume depletion, pregnancy, lactation

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

Interventions

·        Administer 1 hr before or 2 hr after meals.

·        WARNING: Ensure that patient is not pregnant before beginning treatment. Encourage use of contraceptives; if pregnancy is detected, stop drug.

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

·        Monitor patient closely for fall in BP secondary to reduction in fluid volume (due to excessive perspiration and dehydration, vomiting, diarrhea); excessive hypotension may occur.

·        Reduce dosage in patients with impaired renal function.

Teaching points

·        Take drug 1 hour before meals; do not take with food. Do not stop without consulting your health care provider.

·        Be careful of drop in blood pressure (occurs most often with diarrhea, sweating, vomiting, dehydration); if light-headedness or dizziness occurs, consult your health care provider.

·        Severe fetal damage can occur if captopril is taken during pregnancy. Use of contraceptives is advised; if pregnancy should occur, stop drug and notify your health care provider.

·        Avoid over-the-counter medications, especially cough, cold, allergy medications that may contain ingredients that will interact with ACE inhibitors. Consult your health care provider.

·        You may experience these side effects: GI upset, loss of appetite, change in taste perception (limited effects, will pass); mouth sores (frequent mouth care may help); rash; fast heart rate; dizziness, light-headedness (usually passes after the first few days; change position slowly, and limit your activities to those that do not require 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.