Captopril

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Contents

[edit] BRAND NAMES

[edit] STRUCTURE

Captopril.jpg

[edit] MECHANISM OF ACTION

Captopril is an ACE inhibitor. (Angiotensin Converting Enzyme Inhibitor) ACE inhibitors acts by:

  • Inhibiting the formation of angiotensin II from the inactive angiotensin I. Angiotensin II is a potent vasoconstrictor that leads to increased blood pressure.
  • ACE catalyses the breakdown of bradykinin (a powerful vasodilator). Therefore, ACE inhibitors, by inhibiting bradykinin metabolism, increase bradykinin levels, which can contribute to the vasodilator activity
  • Angiotensin II promotes aldosterone release which normally acts to retain sodium and water, therefore ACE inhibitors promote renal excretion of sodium and water (natriuretic and diuretic effects) by blocking angiotensin II stimulation of aldosterone secretion.

Reductions of blood pressure are usually maximal 60 to 90 minutes after oral administration and the duration of effect is dose related. The reduction in blood pressure may be progressive, so to achieve maximal therapeutic effects, several weeks of therapy may be required.

[edit] INDICATIONS

  • Treatment of hypertension, alone or in combination with other antihypertensive agents, especially thiazide-like diuretics. (ACE inhibitors have an effect on blood pressure that is less in black patients than in non-blacks)
  • Treatment of heart failure when given at an adequate dose, usually in combination with diuretics and digitalis. . The beneficial effect of captopril in heart failure does not require the presence of digitalis, however, most controlled clinical trial experience with captopril has been in patients receiving digitalis, as well as diuretic treatment.
  • Treatment of left ventricular dysfunction after Myocardial Infarction
  • Diabetic Nephropathy: Captopril is indicated for the treatment of diabetic nephropathy (proteinuria >500 mg/day) in patients with type I insulin-dependent diabetes mellitus and retinopathy. Captopril decreases the rate of progression of renal insufficiency and development of serious adverse clinical outcomes (death or need for renal transplantation or dialysis).

[edit] DOSAGE

Take 1 hour before meals.

  • Hypertension: 25mg/50mg 2-3 times/day
  • Congestive heart failure: the usual initial daily dosage is 25 mg 3 times/day. Maintenance: 50mg-100mg 3 times/day
  • Left ventricular dysfunction after Myocardial Infarction: Therapy may be initiated as early as three days following a myocardial infarction. After a single dose of 6.25 mg, Captopril therapy should be initiated at 12.5 mg 3 times/day. captopril should then be increased to 25 mg 3 time/day during the next several days and to a target dose of 50 mg 3 times/day over the next several weeks as tolerated
  • Diabetic nephropathy: The recommended dose of Captopril for long term use to treat diabetic nephropathy is 25 mg 3 times/day. Other antihypertensives such as diuretics, beta blockers, centrally acting agents or vasodilators may be used in conjunction with CAPOTEN if additional therapy is required to further lower blood pressure

[edit] CONTRAINDICATIONS

  • Hypersensitivity to Captopril and in patients with a history of angioedema related to previous treatment with an angiotensin converting enzyme inhibitor.
  • Pregnancy and lactation

[edit] WARNINGS AND PRECAUTIONS

  • 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. Emergency therapy, including but not necessarily limited to, subcutaneous administration of a 1:1000 solution of epinephrine should be promptly instituted.
  • Intestinal Angioedema: Intestinal angioedema has been reported in patients treated with ACE inhibitors with symptoms of abdominal pain (with or without nausea or vomiting)

[edit] INTERACTIONS

  • Dual Blockade of the Renin-Angiotensin System (RAS): Dual blockade of the RAS with angiotensin receptor blockers, ACE inhibitors, or aliskiren is associated with increased risks of hypotension, hyperkalemia, and changes in renal function (including acute renal failure) compared to monotherapy. Closely monitor blood pressure, renal function and electrolytes in patients on Captopril and other agents that affect the RAS. Do not co-administer aliskiren with Captopril in patients with diabetes. Avoid use of aliskiren with Capotopril in patients with renal impairment (GFR <60 ml/min).
  • Patients on diuretics may experience an excessive reduction of blood pressure.
  • Caution is advised if non steroidal antiinflammatory drugs NSAIDs are prescribed with ACE inhibitors. (Concomitant use of NSAIDS may result in decreased ACE inhibitor effectiveness). In patients who are elderly, volume-depleted (including those on diuretic therapy), or with compromised renal function who are being treated with NSAIDS, the co-administration of ACE inhibitors may result in further deterioration of renal function. Cases of acute renal failure, usually reversible, have also been reported.
  • Potassium-sparing diuretics (spironolactone, triamterene, amiloride) or potassium supplements may have an additive effect on potassium retention, resulting in hyperkalemia.
  • Lithium carbonate: Increased serum lithium levels and symptoms of lithium toxicity have been reported in patients receiving concomitant lithium and ACE inhibitor therapy. These drugs should be coadministered with caution and frequent monitoring of serum lithium levels is recommended.

[edit] PREGNANCY AND LACTATION

  • Pregnancy Category D (US). ACE inhibitors can cause fetal and neonatal morbidity and mortality when administered to pregnant women (espacially in the second and third trimester of pregnancy). When pregnancy is detected, Captopril should be discontinued as soon as possible.

[edit] SIDE EFFECTS

ACE inhibitors are usually well tolerated. Possible side effects include: Dry irritant cough attributable to accumulation of bradykinin, dizziness (Patients should sit up or get up slowly), fatigue, headache, blurred vision and weakness. GI disturbances include nausea, vomiting, diarrhea, constipation, and abnormal taste.

  • Risk of hyperkalemia due to potassium retention (rarely and especially in patients with renal dysfunction)
  • Angioedema (rare but potentially fatal; ACE inhibitors cause a higher rate of angioedema in black than in non-black patients).
  • Skin rashes

[edit] RELATED LINKS

ACE INHIBITORS: Mechanism of Action, Indications and Side Effects

[edit] REFERENCES

Antihypertensives
ACE inhibitors Benazepril (Lotensin)   Captopril (Capoten)   Cilazapril   Delapril   Enalapril (Renitec, Vasotec)   Fosinopril (Monopril)  Lisinopril (Prinivil, Zestril)   Moexipril (Univasc)  Perindopril (Aceon)  Quinapril (Accupril)  Ramipril (Altace, Triatec)   Trandolapril (Mavik)  Zofenopril (Bifril, Zopranol)
Angiotensin II receptor antagonist Azilsartan (Edarbi)   Candesartan (Atacand)   Eprosartan (Teveten)   Irbesartan (Aprovel, Avapro, Karvea)   Losartan (Cozaar)   Olmesartan (Benicar, Olmetec)   Telmisartan (Micadis)   Valsartan (Diovan, Tareg)
Renin inhibitors Aliskiren (Rasilez, Tekturna)
Alpha-1 blockers Doxazosin (Cardura)   Prazosin (Minipress)   Terazosin (Hytrin)
Alpha-2 agonists (centrally acting) Clonidine (Oral route)   Clonidine (Transdermal) (Catapresan)   Guanfacine (Tenex)   Methyldopa (Aldomet)
Calcium channel blockers Dihydropyridines‎ Amlodipine (Norvasc)   Barnidipine (Vasexten)   Felodipine (Plendil)   Isradipine (Dynacirc)   Lacidipine (Lacipil, Motens)   Lercanidipine (Zanidip)   Manidipine   Nicardipine   Nifedipine (Adalat)   Nisoldipine   Nitrendipine
Benzothiazepine‎ Diltiazem (Cardizem, Taztia XT, Tiazac, Tildiem)
Phenylalkylamine‎ Gallopamil   Verapamil (Calan)
Beta blockers Beta1 selective (cardioselective) Acebutolol (Sectral)   Atenolol (Tenormin)   Betaxolol (Kerlon)   Bisoprolol (Concor)   Celiprolol (Cordiax)   Metoprolol (Betaloc, Lopressor, Toprol-XL)   Nebivolol (Bystolic, Lobivon, Nebilox)
Nonselective (Beta1 and Beta2 blockers) Oxprenolol (Trasitensin)   Propranolol (Inderal)   Timolol (Blocadren)
Nonselective (Beta1, Beta2 and Alpha1 blockers) Carvedilol (Dilatrend)   Labetalol (Trandate)
Beta blocker with intrinsic sympathomimetic activity (ISA) Acebutolol (Sectral)   Celiprolol (Cordiax)
Lipophilic Beta blockers Propranolol (Inderal)   Metoprolol (Betaloc, Lopressor, Toprol-XL)   Oxprenolol (Trasitensin)
Diuretics Carbonic anhydrase inhibitors Acetazolamide (Diamox)
Loop diuretics Bumetanide   Etacrynic acid   Furosemide (Lasix)   Piretanide   Torasemide (Demadex)
Thiazide diuretics Chlorothiazide (Diuril)   Hydrochlorothiazide (Esidrex)
Thiazide-like diuretics Chlortalidone (Hygroton)   Indapamide (Lozol, Lozide)   Metolazone
Potassium-sparing diuretics Epithelial sodium channel blockers: Amiloride (Midamor)   Triamterene (Dyrenium)
Aldosterone receptor antagonists: Potassium canrenoate   Eplerenone (Inspra)   Spironolactone (Aldactone)
Osmotic diuretics Mannitol
Combination therapy Amiloride/Hydrochlorothiazide (Moduretic)   Spironolactone/Hydrochlorothiazide (Aldactazide)