Captopril
Indications
Captopril is used for:
Hypertension, Congestive heart failure, Post Myocardial infarction, Diabetic nephropathy
Adult Dose
Adult: PO HTN Initial: 12.5 mg twice daily. Maintenance: 25-50 mg twice daily. Max: 50 mg 3 times/day.
Elderly: Initially, 6.25 mg bid.
Heart failure Initial: 6.25-12.5 mg 2-3 times/day. Max: 50 mg 3 times/day.
Post MI Start 3 days after MI. Initial: 6.25 mg/day, may increase after several wk to 150 mg/day in divided doses if needed and tolerated.
Diabetic nephropathy 25 mg 3 times/day.
Child Dose
Oral
Hypertension
Child: Neonates and infants: 0.15 mg/kg. Max: 6 mg/kg in 2 or 3 divided doses according to response. Childn and adolescents: 0.3 mg/kg. Max: 6 mg/kg in 2 or 3 divided doses according to response.
Heart failure
Child: Initially, 0.25 mg/kg/day, increased up to 2.5 or 3.5 mg/kg/day in 3 divided doses.
Renal Dose
Renal impairment:
CrCl (ml/min)
<10 Initially, 6.25 mg/day. Max: 37.5 mg/day.
10-20 Initially, 12.5 mg/day. Max: 75 mg/day.
21-40 Initially, 25 mg/day. Max: 100 mg/day.
Administration
Should be taken on an empty stomach. Take on an empty stomach 1 hr before or 2 hr after meals.
Contra Indications
Known hypersensitivity to the drug. Bilateral renal artery stenosis, hereditary angioedema; renal impairment; pregnancy.
Precautions
Patients on diuretics or with sodium depletion should discontinue diuretics or increase sodium intake prior to initiation of therapy. Renal impairment, SLE and other autoimmune collagen disorders and during concurrent use of immunosuppressant or leucopenic drugs, monitor WBC count and urinary protein before and during therapy. Lactation. Porphyria. Severe CHF.
Discontinue as soon as pregnancy detected; during the second and third trimesters of pregnancy, drugs that act directly on the renin-angiotensin have been associated with fetal injury that includes hypotension, neonatal skull hypoplasia, anuria, reversible or irreversible renal failure, and death
Lactation: enters breast milk/not recommended (AAP states compatible with nursing)
Pregnancy-Lactation
Pregnancy Category: C; D in 2nd & 3rd trimesters
Discontinue as soon as pregnancy detected; during the second and third trimesters of pregnancy, drugs that act directly on the renin-angiotensin have been associated with fetal injury that includes hypotension, neonatal skull hypoplasia, anuria, reversible or irreversible renal failure, and death
Lactation: enters breast milk/not recommended (AAP states compatible with nursing)
Interactions
Concurrent treatment w/ NSAIDs reduces hypotensive action and increases the risk of nephrotoxicity. Additive hyperkalaemic effect w/ K supplements, K-sparing diuretics, and other drugs (e.g. heparin). May increase risk of leucopenia w/ procainamide, allopurinol, cytostatic or immunosuppressants. May increase risk of lithium toxicity. Increased risk of nitritoid reactions w/ gold (Na aurothiomalate).
Potentially Fatal: Increased risk of hypotension, hyperkalaemia, and changes in renal function (including acute renal failure) w/ aliskiren in diabetic patients.
Adverse Effects
Side effects of Captopril :
>10%
Hyperkalemia (1-11%)
1-10%
Hypersensitivity rxns (4-7%), Skin rash (4-7%), Dysgeusia (2-4%), Hypotension (1-2.5%), Pruritus (2%), Cough (0.5-2%), Chest pain (1%), Palpitations (1%), Proteinuria (1%), Tachycardia (1%)
Frequency Not Defined
Cardiac arrest, Orthostatic hypotension, Ataxia, Confusion, Depression, Somnolence, Angioedema, Photosensitivity, Neutropenia, ARF if renal artery stenosis, Renal impairment, Impotence
Potentially Fatal: Neutropenia, usually occurs within 3 mth of starting therapy especially in patients with renal dysfunction or collagen diseases. Hyperkalaemia. Anaphylactic reactions.
Mechanism of Action
Captopril competitively inhibits the conversion of angiotensin I (ATI) to angiotensin II (ATII), thus resulting in reduced ATII levels and aldosterone secretion. It also increases plasma renin activity and bradykinin levels. Reduction of ATII leads to decreased Na and water retention. This promotes vasodilation and BP reduction.