CAPTOPRIL
GENERIC NAME: Captopril
BRAND NAME: Capoten, Acepril, Capozide
GENERAL DESCRIPTION
Captopril is the first and potent ACE inhibitors. It is also called vasoactive peptide. It is the only ACE inhibitor that has the capability to enter the central nervous system by crossing the blood brain barrier. Captopril is used as the first line treatment for hypertension, congestive heart failure.
MECHANISM OF ACTION
ACE is an ectoenzyme and glycoprotein which is the main component of RAS. It coverts Angio I to Angio II which controls blood pressure by controlling the volume of body fluids in the body.
Captopril controls blood pressure by the following two steps :
Firstly, Captopril inhibits the Angiotensin converting enzyme and thus inhibits the production of Angiotensin II. As a result of inhibition of Angio II, all the functions performed by Angio II stopped as a result of which captopril decreases systemic vascular resistance without increasing heart rate.
Secondly, captopril inhibits the degradation of Bradykinin, Substance P. Bradykinin is a vasoactive peptide that causes dilation of blood vessels and decrease blood pressure. ACE degrades bradykinin and increase vasoconstriction results in increase blood pressure. ACE I inhibits the degradation of bradykinin which decreases the peripheral vascular resistance thus, control the blood pressure.
PHARMACOKINETICS
Captopril is given orally and has 75% bioavailability. Peak plasma level of captopril is achieved in one hour. It is eliminated in urine.
INDICATIONS
- Hypertension
- Congestive heart failure
- Decrease morbidity and mortality in heart failure
- Myocardial Infarction
- Diabetic nephropathy
- Left ventricle systolic dysfunction
CONTRAINDICATIONS
- Hypersensitivity
- During second and third trimester of pregnancy
- Previous angioedema
SIDE EFFECTS & ADVERSE EFFECTS
- Tachycardia
- Chest pain
- Weakness
- First dose hypotension
- Dry cough (due to bradykinin, more frequent and sometime troublesome)
- Functional renal failure (in renal arterial stenosis patient)
- Hyperkalemia
- Headache
- Dizziness
- Fetal injury
- Urticaria
- Angio oedema
- Proteinuria, neutropenia, rashes and taste disturbance
DRUG INTERACTION
- Food reduce the bioavailability of captopril.
- Potassium supplements and potassium-sparing diuretics results in hyperkalemia when given with captopril.
- NSAIDs may impair the hypotensive effects of captopril and increase blood pressure.
- Antacids may reduce the bioavailability of captopril
- Capsaicin may worsen the cough induced by captopril.
- Captopril may increase plasma levels of Digoxin and lithium
- Hypersensitivity reaction of Allopurinol may increase with when given with captopril.
- Captopril may increase the effects of RAAS blockers, NSAIDS, anticoagulants, DPP4 inhibitors and cyclosporine.
- Alcohol may increase the antihypertensive effect of captopril.
NURSING INTERVENTIONS
- Take complete health history of patient.
- Monitor blood pressure and pulse frequently to avoid initial dose hypotension.
- Daily check the weight and fluid overload.
- Check the s/s of angioedema (swelling of face and extremities)
- Monitor BUN, serum potassium, creatinine, AST, ALT, serum bilirubin level
- ACEI may cause false urine acetone level
- Monitor kidney function.
PATIENT EDUCATION
- Take medicine one hour prior meal.
- Counsel the patient right dose and time of medicine
- Low blood pressure may be experienced, discontinue medicine when severe hypotension occur and report health practitioner.
- Drink plenty of water.
- Increase in urination.
- Do not take alcohol it will further decrease blood pressure.
- Don not breast feed.
- Avoid strict exercise routine while taking the medicine
- Avoid use of potassium supplements and potassium rich diet.
- Ask HP prior taking multivitamins or fortified supplements
- Report immediate if having persistent cough specially at night.