Captopril

ADMINISTRATION ROUTES:

PO, NG

ALTERNATIVE NAMES:

Capoten

ICU INDICATIONS:

1. Hypertension

2. Congestive heart failure or left ventricular dysfunction after myocardial infarction

3. Diabetic nephropathy

PRESENTATION AND ADMINISTRATION:

PO / NG:

Apo-captopril & capoten tablets (12.5mg, 25mg, 50 mg white tablets) Capoten solution (5 mg/mL) clear and colourless

Tablets can be crushed for NG administration. Liquid is also available

DOSAGE:

PO/NG:

6.25mg q8hrly increased to maximum of 50 mg q8hrly

DOSAGE IN RENAL FAILURE AND RENAL REPLACEMENT THERAPY:

Dose in renal impairment

Dose in renal replacement therapy

Note: There have been reports of an association of hypersensitivity-like (anaphylactoid) reactions during haemodialysis with high-flux dialysis membranes (e.g. AN69) in patients receiving ACE inhibitors

DOSAGE IN PAEDIATRICS:

0.1 mg/kg q8hrly. Increase if required to a maximum of 2 mg/kg q8hrly

CLINICAL PHARMACOLOGY:

Captopril is a specific competitive inhibitor of angiotensin I-converting enzyme (ACE), the enzyme responsible for the conversion of angiotensin I to angiotensin II

CONTRAINDICATIONS:

1. Hypersensitivity to captopril or any other angiotensin-converting enzyme inhibitor (e.g. a patient who has experienced angioedema during therapy with any other ACE inhibitor)

2. Cardiogenic shock

WARNINGS:

Anaphylactoid and Possibly Related Reactions

Captopril can cause anaphylactoid reactions

Head and Neck Angioedema

Angioedema involving the extremities, face, lips, mucous membranes, tongue, glottis or larynx has been seen in patients treated with ACE inhibitors, including captopril. If angioedema involves the tongue, glottis or larynx, airway obstruction may occur and be fatal. Swelling confined to the face, mucous membranes of the mouth, lips and extremities has usually resolved with discontinuation of captopril; some cases required medical therapy

Intestinal Angioedema

Intestinal angioedema has been reported in patients treated with ACE inhibitors. These patients presented with abdominal pain (with or without nausea or vomiting); in some cases there was no prior history of facial angioedema and C-1 esterase levels were normal

Neutropaenia/Agranulocytosis

Neutropaenia (<1000/mm3) with myeloid hypoplasia has resulted from use of captopril

Hypotension in Heart Failure Patients

Caution should be observed when initiating therapy in patients with heart failure. Patients with heart failure given captopril commonly have some reduction in blood pressure. In patients with symptomatic hypotension this may require temporarily reducing the dose of captopril, or diuretic, or both, and volume repletion

Hepatic Failure

Rarely, ACE inhibitors have been associated with a syndrome that starts with cholestatic jaundice and progresses to fulminant hepatic necrosis and (sometimes) death. The mechanism of this syndrome is not understood. Patients receiving ACE inhibitors who develop jaundice or marked elevations of hepatic enzymes should discontinue the ACE inhibitor

PRECAUTIONS:

General:

Some patients with renal disease, particularly those with severe renal artery stenosis, have developed increases in serum creatinine after reduction of blood pressure with captopril. Captopril dosage reduction and/or discontinuation of diuretic may be required. Elevations in serum potassium have been observed in some patients treated with ACE inhibitors, including captopril

Presumably due to the inhibition of the degradation of endogenous bradykinin, persistent nonproductive cough has been reported with all ACE inhibitors, always resolving after discontinuation of therapy. ACE inhibitor-induced cough should be considered in the differential diagnosis of cough

Laboratory Tests:

No tests in addition to routine ICU tests are required

Drug/Laboratory Test Interactions:

Captopril may cause a false-positive urine test for acetone

IMPORTANT DRUG INTERACTIONS IN ICU:

Increased serum lithium levels and symptoms of lithium toxicity have been reported in patients receiving concomitant lithium and ACE inhibitor therapy.

The risk of hypotension increases if captopril is co-administered with other antihypertensives

ADVERSE REACTIONS:

Body as a Whole:

Gynaecomastia, anaphylactoid reactions, angioedema

Cardiovascular:

Cardiac arrest, cerebrovascular accident / insufficiency, rhythm disturbances, orthostatic hypotension, syncope

Dermatological:

Bullous pemphigus, erythema multiforme (Stevens Johnson syndrome), exfoliative dermatitis

Gastrointestinal:

Pancreatitis, glossitis, dyspepsia, jaundice, hepatitis, rare causes of hepatic necrosis, cholestasis

Haematological:

Anaemia (including cases of haemolytic anaemia), thrombocytopaenia, neutropaenia

Metabolic:

Hyponatraemia

Musculoskeletal:

Myalgia, myasthenia

Nervous system:

Ataxia, confusion, depression, nervousness, somnolence

Respiratory system:

Bronchospasm, eosinophilic pneumonia, angioedema

Urogenital system:

Renal failure, proteinuria