Captopril

Captopril

[12.5mg tablets 2 cents]

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, 50mg white tablets)
    Capoten solution (5mg/ml) – clear and colourless
    Tablets can be crushed for NG administration and liquid is also available.

DOSAGE:

  • PO:
    6.25mg PO TDS increased to maximum of 50mg PO TDS.

DOSAGE IN RENAL FAILURE AND RENAL REPLACEMENT THERAPY:

  • Dose in renal impairment [GFR (ml/min)]
    <10: start with 6.25mg or less and increase gradually
    10-20: start with 6.25mg or less and increase gradually
    >20-50: start with 6.25mg or less and increase gradually
  • Dose in renal replacement therapy
    CAPD: start with 6.25mg or less and increase gradually
    HD: start with 6.25mg or less and increase gradually
    CVVHDF: start with 6.25mg or less and increase gradually

    Note: Recent clinical observations have shown an association of hypersensitivity-like (anaphylactoid) reactions during hemodialysis with high-flux dialysis membranes (e.g., AN69) in patients receiving ACE inhibitors.

DOSAGE IN PAEDIATRICS:

  • 0.1mg/kg 8hrly; increased if required to a maximum of 2mg/kg 8hrly.

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 FOR THE 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 coadministered 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), exfoliatice dermatitis
  • Gastrointestinal:
    Pancreatitis, glossitis, dyspepsia, jaundice, hepatitis, rare causes of hepatic necrosis, cholestasis
  • Haematological: Anaemia (including cases of haemolytic anaemia), thrombocytopenia, neutropenia
  • Metabolic:
    Hyponatraemia
  • Musculoskeletal:
    Myalgia, myasthenia
  • Nervous system:
    Ataxia, confusion, depression, nervousness, somnolence
  • Respiratory system:
    Bronchospasm, eosinophilic pneumonia, angioedema
  • Urogenital system:
    Renal failure, proteinuria

Critical Care Drug Manual

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