Which medication should be reduced or stopped first in a patient experiencing hypotension while taking Losartan (an angiotensin II receptor antagonist) and Atenolol (a beta blocker)?

From the Guidelines

When a patient has low blood pressure while taking both losartan and atenolol, it's generally recommended to reduce or stop the atenolol first. This approach is based on the understanding that beta-blockers like atenolol can have a more pronounced effect on lowering blood pressure compared to angiotensin receptor blockers (ARBs) like losartan 1. The Losartan Intervention for Endpoint Reduction (LIFE) study, which compared losartan to atenolol in patients with hypertension and left ventricular hypertrophy, found that losartan had a lower risk for cardiovascular end points and all-cause mortality, suggesting its importance in managing certain conditions 1.

Key Considerations

• Atenolol directly lowers heart rate and blood pressure, making it a logical first choice to adjust in cases of hypotension.
• Reducing the atenolol dose by half and monitoring the patient's blood pressure closely can help determine if further adjustments are needed.
• Losartan provides important benefits for patients with conditions like heart failure or diabetic kidney disease, and its maintenance is initially preferred over stopping it.
• Regular monitoring of blood pressure and patient symptoms during medication adjustments is crucial.

Management Approach

• Start by reducing the atenolol dose by half to assess the impact on blood pressure.
• If blood pressure remains low after a few days, consider stopping atenolol completely while closely monitoring the patient.
• If blood pressure is still too low after stopping atenolol, then consider reducing the losartan dose, keeping in mind the potential benefits of losartan for certain patient populations 1.
• Always advise the patient to report symptoms like dizziness, especially when standing up, during the adjustment period.

From the FDA Drug Label

In patients with an activated renin-angiotensin system, such as volume- or salt-depleted patients (e.g., those being treated with high doses of diuretics), symptomatic hypotension may occur after initiation of treatment with losartan. If bradycardia or hypotension requiring treatment or any other untoward effects occur, atenolol should be discontinued.

The medication that should be reduced or stopped first in a patient experiencing hypotension while taking Losartan and Atenolol is Atenolol.

• Reason: Both medications can cause hypotension, but Atenolol, a beta blocker, has a more direct effect on heart rate and blood pressure, and its discontinuation is explicitly mentioned in the context of hypotension in its label 2.
• Clinical Decision: In the absence of explicit guidance on the simultaneous use of Losartan and Atenolol in the context of hypotension, prioritizing the discontinuation of Atenolol is a conservative approach, as it directly addresses potential bradycardia and hypotension mentioned in its label 2.

From the Research

Medication Reduction in Hypotension

In a patient experiencing hypotension while taking Losartan and Atenolol, the decision to reduce or stop one of these medications should be based on their respective effects on blood pressure and potential interactions.

• Losartan is an angiotensin II receptor antagonist that provides a specific blockade of the actions of angiotensin II, leading to a decrease in blood pressure 3.
• Atenolol is a beta blocker that reduces blood pressure by decreasing cardiac output and reducing the release of renin, which in turn reduces the formation of angiotensin II 4.

Comparative Effects on Blood Pressure

Both Losartan and Atenolol have been shown to be effective in reducing blood pressure in patients with hypertension.

• A study comparing the efficacy of Losartan and Atenolol in patients with mild to moderate essential hypertension found that both medications reduced blood pressure to a similar extent 4.
• Another study found that Losartan was more effective than Atenolol in preventing cardiovascular morbidity and death, predominantly stroke, in hypertensive patients without clinically evident vascular disease 5.

Considerations for Reduction or Cessation

When considering which medication to reduce or stop first in a patient experiencing hypotension, the following factors should be taken into account:

• The patient's individual response to each medication, including any adverse effects or interactions.
• The potential impact of reducing or stopping one medication on the patient's blood pressure and overall cardiovascular risk.
• The presence of any comorbid conditions, such as heart failure or renal disease, that may influence the decision.

Recommendations

Based on the available evidence, it may be reasonable to consider reducing or stopping Atenolol first in a patient experiencing hypotension while taking Losartan and Atenolol, as Atenolol has been shown to have a greater impact on heart rate and may be more likely to contribute to hypotension 6, 7. However, this decision should be made on a case-by-case basis, taking into account the individual patient's circumstances and medical history.