Captopril

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Contents 1 Introduction 2 Indications 3 Pharmacokinetics 4 Adverse-effects 5 Drug-interactions 6 Mechanism-of-action 7 More General Terms 8 Additional Terms 9 Internet Database 10 References

Introduction

• Tradename: Capoten.

Indications

• hypertension: Start 25 mg PO BID/ TID, max 450 mg/day.
• congestive heart failure:

• start 6.25-12.5 mg PO TID, max 150 mg/day

• left ventricular systolic dysfunction after myocardial infarction

• start 6.25-12.5 mg PO TID, max 450 mg/day

• diabetic nephropathy: 25 mg PO TID

• Tabs: 12.5, 25, 50, 100 mg.

Pharmacokinetics

• oral bioavailability is about 60%

• food impairs absorption [6]

• 30% is bound to plasma proteins
• 50% is metabolized by the liver
• 30% is excreted into the urine
• onset of action: (single dose) 15-60 minutes
• duration of action: (single dose) 6-12 hours
• 1/2 life is 1.7 hours [4] in healthy individuals, but is prolonged in patients with renal failure or CHF
  

• elimination via liver
• elimination via kidney
• 1/2life = 6-8 hours
• 1/2life = 1.7 hours

Adverse-effects

• common (> 10%)

• transient, non-productive, dry cough

• not common (1-10%)

• dyspnea, oliguria, tachycardia, chest pain, palpitations, insomnia, paresthesias, headache, dizziness, fatigue, malaise, abdominal pain, vomiting, nausea, diarrhea, anorexia, constipation, rash, pruritis, alopecia,

• uncommon (< 1%)

• hypotension, hyperkalemia, neutropenia, agranulocytosis*, angioedema*, proteinuria, worsening of renal failure, disturbances in taste

• * side effects of angioedema & agranulocytosis may be more common in captopril than in other ACE inhibitors because of sulfhydryl group, especially in patients with connective tissue disease or serum creatinine > 1.5 mg/dL
  

• drug adverse effects of ACE inhibitors

Drug-interactions

• NSAIDs may reduce hypotensive effect
• phenothiazines may increase pharmacologic effects of captopril
• high risk of hypersensitivity reactions when used in combination with allopurinol
• captopril increases serum levels of lithium & digoxin
• agents that increase serum K+

• K+ salts
• K+ sparing diuretics

• spironolactone
• triamterene
  

• drug interaction(s) of renin-angiotensin inhibitors with trimethoprim-sulfamethoxazole
• drug interaction(s) of lithium carbonate with ACE inhibitors
• drug interaction(s) of ACE inhibitors with aliskiren
• drug interaction(s) of ACE inhibitors with angiotensin II receptor antagonists
• drug interaction(s) of potassium chloride with ACE inhibitors
• drug interaction(s) of spironolactone with ACE inhibitors
• drug interaction(s) of diuretics with ACE inhibitors
• drug interaction(s) of beta blockers with ACE inhibitors
• drug interaction(s) of NSAIDs with ACE inhibitors
• drug interaction(s) of ACE inhibitors, angiotensin II receptor antagonists & beta-blockers
• drug interaction(s) of NSAIDs, diuretics & ACE inhibitors

Mechanism-of-action

• Like other ACE inhibitors, captopril blocks conversion of angiotensin 1 to angiotensin 2 by inhibiting angiotensin converting enzyme.
• Captopril improves symptoms of heart failure, improves exercise tolerance & improves functional capacity in patients with heart failure. Captopril also attenuates ventricular enlargement & improves hemodynamics & survival in patients with left ventricular dysfunction secondary to myocardial infarction. It is likely that other ACE inhibitors have similar beneficial effects, but have been less well studied.

More General Terms

• pyrrolidine; tetrahydropyrrole
• carboxylic acid
• thiol; sulhydryl compound; mercaptan
• angiotensin-converting enzyme [ACE] inhibitor

Additional Terms

• angiotensin converting enzyme (ACE)
• angiotensin II
• Captopril Prevention Project (CAPPP)
• captopril scan (ACE inhibitor renography)
• captopril-renin stimulation test
• ELITE II Study

Internet Database

PubChem: 44093
PubChem: 2550

References

1. Goodman and Gilman's The Pharmacological Basis of Therapeutics, 8th ed. Gilman et al, eds. Permagon Press/McGraw Hill, 1990. pg 760-1
2. The Pharmacological Basis of Therapeutics, 9th ed. Gilman et al, eds. Permagon Press/McGraw Hill, 1996
3. Manual of Medical Therapeutics, 28th ed, Ewald & McKenzie (eds), Little, Brown & Co, Boston, 1995, pg 117
4. Drug Information & Medication Formulary, Veterans Affairs, Central California Health Care System, 1st ed., Ravnan et al eds, 1998
5. Kaiser Permanente Northern California Regional Drug Formulary, 1998
6. Harrison's Principles of Internal Medicine, 14th ed. Fauci et al (eds), McGraw-Hill Inc. NY, 1998, pg 470

captopril (Capoten)