Angiotensin-converting enzyme (ACE) inhibitors: Nursing pharmacology

Angiotensin converting enzyme inhibitors, or ACE inhibitors for short, are a group of medications that help decrease blood pressure and are typically used to treat hypertension or heart failure, but they can be also administered to clients who have recently had a myocardial infarction.

Now, ACE inhibitors usually end in “-pril”, and include enalapril, lisinopril, ramipril, benazepril, and captopril.

Most of these medications are taken orally, but there’s one ACE inhibitor called enalaprilat that can be administered intravenously for hypertension or severe heart failure when oral treatment isn’t practical. However, it’s not recommended for acute heart failure or myocardial infarction.

Alright, ACE inhibitors work by inhibiting the action of an enzyme called angiotensin-converting enzyme, or ACE for short, preventing it from converting angiotensin I into its active form angiotensin II. Angiotensin II causes blood vessels to constrict, which increases the blood pressure.

In addition, it stimulates the adrenal glands to release aldosterone, which increases reabsorption of sodium and water in the kidneys. This results in increased blood volume, which also contributes to increased blood pressure.

So once ACE inhibitors are administered, there’s less angiotensin II in the bloodstream, which decreases vasoconstriction, as well as decreased aldosterone release by the adrenals, leading to natriuresis, or excretion of sodium along with water by the kidneys. In this way, ACE inhibitors effectively lower the blood pressure.

Now, the most common side effects of ACE inhibitors are mild and nonspecific, such as a headache, dizziness, and fatigue. However, many clients also complain of a constant, dry, irritating cough.

That’s because normally, ACE also breaks down bradykinin, so when the client takes ACE inhibitors, bradykinins accumulate, and they’re thought to induce the cough reflex. In fact, this is a common reason for quitting ACE inhibitors and switching to another medication.

Less frequently, bradykinin accumulation may lead to increased capillary permeability, which results in fluid accumulation and swelling of the eyes, lips, tongue, pharynx, and glottis; this is called angioedema, and can be life threatening.

Other side effects of ACE inhibitors include tachycardia, as well as hypotension, which tends to occur with the first few doses.

Finally, ACE inhibitors decrease potassium excretion in the urine, and this could lead to hyperkalemia, so it’s important for clients who are taking ACE inhibitors to avoid taking potassium supplements and salt substitutes that contain potassium.

As far as contraindications go, ACE inhibitors should be avoided in clients who also take potassium sparing diuretics like spironolactone, or have another underlying cause of hyperkalemia.

Also, ACE inhibitors should be given with caution in those with renal insufficiency. Lastly, as a boxed warning, ACE inhibitors and other medications with a similar mechanism of action are contraindicated during pregnancy, since they may cause fetal injury.

Alright, if your client is prescribed an ACE inhibitor, perform a baseline assessment, including vital signs, ECG, CBC, urinalysis, sodium, potassium, creatinine, and BUN.

For female clients of childbearing age, obtain a negative pregnancy test, and advise them to let their healthcare provider know if they plan to become pregnant.

If the medication is prescribed for heart failure, assess your client’s weight, lung sounds, and for the presence of edema or dyspnea.

Next, be sure to explain why the medication is prescribed and describe common side effects your client should watch for.

Let them know that hypotension can often occur with the first few doses, so instruct your client to be mindful of any feeling of dizziness or weakness, and to make position changes slowly until they adjust to their medication.