Which medication can cause bradycardia: Losartan (Angiotensin II Receptor Antagonist) 100 milligrams once daily or Aripiprazole (Atypical Antipsychotic) 15 milligrams once daily?

From the Guidelines

Between Losartan 100 mg once daily and Aripiprazole 15 mg (10 mg × 1.5 tablets) once daily, neither is directly associated with a high risk of bradycardia based on the provided evidence, but Aripiprazole may have a slightly higher risk due to its potential effects on cardiac conduction. The provided evidence does not directly link Losartan or Aripiprazole with a high risk of bradycardia 1. However, it discusses various cardiovascular drugs and their potential side effects, including antiarrhythmic drugs that can increase the risk of bradycardia and AV block.

• Losartan, an angiotensin II receptor blocker (ARB), is not directly mentioned as a cause of bradycardia in the evidence provided.
• Aripiprazole, an atypical antipsychotic, is not discussed in the context of bradycardia in the provided evidence, but its potential to affect cardiac conduction through various receptors could theoretically contribute to bradycardia, although this is not explicitly stated. Key points to consider:
• The risk of bradycardia is more commonly associated with antiarrhythmic drugs, particularly class II and IV antiarrhythmic drugs or digoxin, as mentioned in the evidence 1.
• Monitoring for symptoms of bradycardia, such as dizziness, fatigue, or syncope, is crucial, especially in patients with pre-existing cardiac conditions or those initiating therapy with medications that may affect heart rate. Given the information provided and the focus on minimizing morbidity, mortality, and improving quality of life, it is essential to monitor patients on either medication for any signs of bradycardia, although the direct risk association is not clearly established for either Losartan or Aripiprazole based on the evidence 1.

From the FDA Drug Label

Common adverse reactions (reported in at least 5% of all overdose cases) reported with oral aripiprazole overdosage (alone or in combination with other substances) include vomiting, somnolence, and tremor Other clinically important signs and symptoms observed in one or more patients with aripiprazole overdoses (alone or with other substances) include acidosis, aggression, aspartate aminotransferase increased, atrial fibrillation, bradycardia, coma, confusional state, convulsion, blood creatine phosphokinase increased, depressed level of consciousness, hypertension, hypokalemia, hypotension, lethargy, loss of consciousness, QRS complex prolonged, QT prolonged, pneumonia aspiration, respiratory arrest, status epilepticus, and tachycardia.

• Aripiprazole can cause bradycardia as it is listed as one of the clinically important signs and symptoms observed in patients with aripiprazole overdoses 2.
• There is no mention of bradycardia as an effect of Losartan in the provided drug label, and it is stated that "There was essentially no change in average heart rate in losartan-treated patients in controlled trials" 3.

From the Research

Medication Comparison

• Losartan 100 mg once a day: There is no evidence in the provided studies to suggest that Losartan causes bradycardia 4, 5, 6, 7, 8.
• Aripiprazole 10 mg 1.5 tablet once a day: A study found that Aripiprazole can cause symptomatic bradycardia, as evidenced by a case report of a patient who developed bradycardia after initiation of oral Aripiprazole 4.

Mechanism and Prevalence

• The exact mechanism of Aripiprazole-induced bradycardia is not well understood, but it is thought to be related to the drug's effects on the autonomic nervous system 4.
• Bradycardia is a relatively uncommon side effect of Aripiprazole, but it can be severe and warrants consideration when initiating antipsychotic therapy 4.
• Another study found that orthostatic hypotension, which can be associated with bradycardia, is not a reason to down-titrate antipsychotic therapy, even in the setting of a lower blood pressure goal 6.

Dosage and Equivalence

• The minimum effective dose of Aripiprazole is 10 mg/day, which is equivalent to 1.33 olanzapine equivalents 7.
• The dosage of Aripiprazole in the provided scenario (10 mg 1.5 tablet once a day) is higher than the minimum effective dose, which may increase the risk of side effects such as bradycardia 7.