Potassium with Cilazapril Interaction Details

Brand Names Associated with Potassium

Medical Content Editor Dr. Brian Staiger, PharmD
Last updated Nov 11, 2023

Interaction Effect

Hyperkalemia

Interaction Summary

Cilazapril is an angiotensin-converting enzyme (ACE) inhibitor capable of lowering aldosterone levels, which in turn, can result in potassium retention. There have been case reports of severe hyperkalemia and arrhythmias due to ingestion of potassium supplements in conjunction with ACE inhibitor therapy. In patients with renal dysfunction or in those receiving potassium supplements, the increase in serum potassium is usually evident within two to four days .

Severity

Major

Onset

Delayed

Evidence

Theoretical

How To Manage Interaction

Although such increases are usually transient, monitor serum potassium levels for persistent elevations in patients on this combination, especially those patients with concurrent renal dysfunction, or the elderly. Patients on angiotensin-converting enzyme inhibitor therapy should be alerted to the potential danger of excessive potassium in the diet, including potassium-containing salt substitutes or diet supplements.

Mechanism Of Interaction

Lowered aldosterone levels

Literature Reports

A) An 81-year old woman with a history of congestive heart failure and acute myocardial infarction presented to the hospital with chest discomfort. The patient had been taking diltiazem, furosemide, digoxin, isosorbide mononitrate, and aspirin regularly in addition to captopril 25 mg three times daily. The patient was also taking potassium 1200 mg twice daily due to persistent hypokalemia during an earlier hospitalization. Upon examination and measurement of serum electrolytes, the patient had a slow atrial fibrillation, heart rate of 36 beats per minute, and a serum potassium level of 8.2 mmol/L. After treatment with calcium gluconate, dextrose, insulin, furosemide, and sodium polystyrene sulfonate, the patient's serum potassium level decreased to 5.4 mmol/L and normal sinus rhythm returned. The authors noted that life-threatening hyperkalemia may occur late during the course of treatment with ACE inhibitors, and suggested monitoring of renal function and potassium .

B) A 59-year old man was admitted to the hospital for treatment of an acute exacerbation of congestive heart failure and hypertension. The patient's serum potassium level on admission was 4.3 mEq/L. Captopril 12.5 mg every eight hours was then added to the patient's regimen of furosemide and oral nitrates. The patient's serum potassium level began to increase slowly over the next few days to a level of 5.0 mEq/L. A review of the patient's chart showed that he had been on a salt-restricted diet. The patient had been using several hospital-provided salt substitute packages during every meal, which contained approximately 13 mEq of potassium per gram. When the salt substitute was discontinued, serum potassium levels fell to 4.8 mEq/L .

C) A 64-year old woman presented to the emergency room with a 36-hour history of intermittent vomiting. The patient was being treated with lisinopril 10 mg daily, and theophylline 600 mg daily. The patient had lost 33.8 kg over the previous six months on a daily diet consisting of a protein supplement containing 48 mmol potassium and an evening salad containing a salt substitute with 72 mmol potassium. The patient complained of severe weakness, had a serum potassium level of 9.7 mmol/L, and showed electrocardiographic changes consistent with hyperkalemia, including a widening of the QRS complex. After the patient was treated with calcium gluconate, insulin, dextrose, and sodium bicarbonate intravenously, serum potassium levels decreased to normal over the next 12 hours. The authors suggested that the patient experienced life-threatening hyperkalemia due to lisinopril inhibition of aldosterone secretion in addition to a diet containing more than 120 mmol potassium per day .

D) Two patients who experienced hyperkalemia due to the addition of salt substitutes containing potassium have been described. The first patient, a 67-year-old male taking atenolol 100 mg daily, furosemide 40 mg daily, aspirin 75 mg daily, and lisinopril 20 mg daily, presented with a three-day history of dizziness and vomiting. His serum potassium was 7.6 mmol/L, and treatment with insulin and dextrose was initiated. An electrocardiogram showed a marked sinus bradycardia, and the patient suffered a brief cardiac arrest. It was discovered that the patient had been adding 70 mmol of potassium daily to his diet in the form of a salt substitute one week prior to admission, which was believed to be the cause of his hyperkalemia. The second patient, a 64-year-old male, was started on enalapril 2.5 mg twice daily for hypertension and had a serum potassium level of 5 mmol/L. Four months later, his potassium had increased to 7 mmol/L. The hyperkalemia was corrected with insulin and dextrose, while the enalapril was discontinued. The patient mentioned that he had started using a salt substitute, and further investigation revealed that he was adding 133 mmol of potassium daily into his diet from the salt substitute. Enalapril was restarted, the salt substitute was discontinued, and two months later his potassium was 5.7 mmol/L .

Potassium Overview

• Potassium is essential for the proper functioning of the heart, kidneys, muscles, nerves, and digestive system. Usually the food you eat supplies all of the potassium you need. However, certain diseases (e.g., kidney disease and gastrointestinal disease with vomiting and diarrhea) and drugs, especially diuretics ('water pills'), remove potassium from the body. Potassium supplements are taken to replace potassium losses and prevent potassium deficiency.

• This medication is sometimes prescribed for other uses; ask your doctor or pharmacist for more information.

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Definitions

Severity Categories

Contraindicated

These drugs, generally, should not be used together simultaneously due to the high risk of severe adverse effects. Combining these medications can lead to dangerous health outcomes and should be strictly avoided unless otherwise instructed by your provider.

Major

This interaction could result in very serious and potentially life-threatening consequences. If you are taking this drug combination, it is very important to be under close medical supervision to minimize severe side effects and ensure your safety. It may be necessary to change a medication or dosage to prevent harm.

Moderate

This interaction has the potential to worsen your medical condition or alter the effectiveness of your treatment. It's important that you are monitored closely and you potentially may need to make adjustments in your treatment plan or drug dosage to maintain optimal health.

Minor

While this interaction is unlikely to cause significant problems, it could intensify side effects or reduce the effectiveness of one or both medications. Monitoring for changes in symptoms and your condition is recommended, and adjustments may be made if needed to manage any increased or more pronounced side effects.

Onset

Rapid: Onset of drug interaction typically occurs within 24 hours of co-administration.

Delayed: Onset of drug interaction typically occurs more than 24 hours after co-administration.

Evidence

Level of documentation of the interaction.

Established: The interaction is documented and substantiated in peer-reviewed medical literature.

Theoretical: This interaction is not fully supported by current medical evidence or well-documented sources, but it is based on known drug mechanisms, drug effects, and other relevant information.

How To Manage The Interaction

Provides a detailed discussion on how patients and clinicians can approach the identified drug interaction as well as offers guidance on what to expect and strategies to potentially mitigate the effects of the interaction. This may include recommendations on adjusting medication dosages, altering the timing of drug administration, or closely monitoring for specific symptoms.

It's important to note that all medical situations are unique, and management approaches should be tailored to individual circumstances. Patients should always consult their healthcare provider for personalized advice and guidance on managing drug interactions effectively.

Mechanism Of Interaction

The theorized or clinically determined reason (i.e., mechanism) why the drug-drug interaction occurs.

Disclaimer: The information provided on this page is for informational purposes only and should not be considered medical advice. Always consult with a qualified healthcare professional regarding your specific circumstances and medical conditions.

Where Does Our Information Come From?

Information for our drug interactions is compiled from several drug compendia, including:

• Gold Standard Drug Database
• Micromedex
• Lexicomp
• DrugBank

The prescribing information for each drug, as published on DailyMED, is also used. 

Individual drug-drug interaction detail pages contain references specific to that interaction. You can click on the reference number within brackets '[]' to see what reference was utilized.

The information posted is fact-checked by HelloPharmacist clinicians and reviewed quarterly.