Atenolol vs Bisoprolol

## Overview

Both atenolol and bisoprolol are cardioselective beta-1 blockers, but bisoprolol has proven mortality benefit in HFrEF (CIBIS-II), while atenolol lacks this evidence. Bisoprolol is also more selective and has a more favorable PK profile.

## Mechanism of Action

Both selectively block beta-1 adrenoceptors. Bisoprolol has a higher beta-1:beta-2 selectivity ratio (up to 1:120) compared to atenolol (1:35), offering greater cardioselectivity, especially relevant at higher doses.

## Pharmacokinetics

Atenolol: half-life 6–9 h, renally eliminated, no hepatic metabolism. Bisoprolol: half-life 10–12 h, dual elimination (50% hepatic, 50% renal as unchanged drug), bioavailability ~90%. Bisoprolol's superior bioavailability means more predictable plasma levels.

## Clinical Evidence

Bisoprolol has pivotal evidence from CIBIS-II (HFrEF, 34% mortality reduction). Atenolol's ASCOT-BPLA comparison to amlodipine suggested inferior outcomes for hypertension, questioning its role as a preferred antihypertensive. Bisoprolol is guideline-recommended for HFrEF; atenolol is not.

## Key Takeaways

- Bisoprolol superior cardioselectivity and HFrEF evidence
- Atenolol limited to hypertension/angina; no HF mortality data
- Bisoprolol once-daily, high bioavailability, dual elimination