What is the blood concentration‑time profile for a single immediate‑release atenolol (50 mg) tablet in an adult with normal renal function?

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Last updated: October 1, 2026 • View editorial policy

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Atenolol Immediate Release Blood Concentration-Time Profile

Following a single 50 mg oral dose of immediate-release atenolol in adults with normal renal function, peak plasma concentrations are reached between 2-4 hours post-ingestion, with approximately 50% oral bioavailability and an elimination half-life of 6-7 hours. 1

Key Pharmacokinetic Parameters

The blood concentration-time curve for atenolol demonstrates the following characteristics:

Absorption Phase

  • Bioavailability: Approximately 50% of the oral dose is absorbed from the gastrointestinal tract 1, 2
  • Time to peak (Tmax): 2-4 hours after oral administration 1
  • Peak concentration (Cmax): Dose-dependent, with studies showing mean Tmax around 3.0 hours 2

Distribution and Elimination

  • Elimination half-life (t½): 6-7 hours in patients with normal renal function 1
    • More precise measurements show 6.06 ± 2.02 hours 2
  • Protein binding: Only 6-16% bound to plasma proteins 1
  • Volume of distribution: 0.173 L/kg (central compartment) 2

Excretion Profile

  • Renal excretion: Over 85% of absorbed drug excreted unchanged in urine within 24 hours 1
  • Plasma clearance: 10.7 ± 1.27 L/hr 2
  • Renal plasma clearance: 10.4 ± 1.14 L/hr, accounting for nearly all total clearance 2

Concentration-Time Curve Characteristics

The typical profile shows:

  1. Rapid absorption phase: 0-3 hours with ascending concentrations
  2. Peak plateau: 2-4 hours post-dose
  3. Elimination phase: Gradual decline with consistent first-order kinetics over 24+ hours
  4. Duration of effect: Beta-blocking and antihypertensive effects persist for at least 24 hours despite declining plasma levels 1

Clinical Implications

The pharmacodynamic effect (reduction in exercise tachycardia) is maximal at 2-4 hours and persists beyond 24 hours, allowing once-daily dosing. 1 This dissociation between plasma concentration and clinical effect is characteristic of atenolol.

Important Caveats

  • Renal impairment dramatically alters the profile: When creatinine clearance falls below 35 mL/min/1.73m², significant accumulation occurs with elimination half-life extending to 16-27 hours 1
  • Dose linearity: Pharmacokinetics are dose-independent across the therapeutic range (25-100 mg), with Cmax varying linearly with dose 2, 3
  • Minimal hepatic metabolism: Unlike propranolol or metoprolol, atenolol undergoes little to no hepatic metabolism, making it more predictable but highly dependent on renal function 1

The concentration-time profile demonstrates a three-compartment model with elimination from the central compartment 2, resulting in relatively consistent plasma drug levels with approximately 4-fold interpatient variation 1.

References

2
Research

Kinetics and absolute bioavailability of atenolol.

Clinical pharmacology and therapeutics, 1979

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