Equivalent Dose Conversion: 80 mg Propranolol to Atenolol
For an adult patient taking 80 mg propranolol daily, the equivalent atenolol dose is 50 mg once daily, as 50 mg atenolol has been shown to have greater antihypertensive effect than 80 mg propranolol and equivalent efficacy to 160 mg propranolol. 1
Evidence-Based Dose Equivalency
Direct Comparative Data
A double-blind crossover study in hypertensive patients demonstrated that 50 mg atenolol once daily had a greater antihypertensive effect than 80 mg propranolol once daily and was as effective as 160 mg propranolol daily 1
The same study showed that both drugs produced equivalent heart rate slowing, but atenolol at 50 mg lowered mean arterial pressure more effectively than propranolol 80 mg 1
In angina pectoris treatment, atenolol 100 mg twice daily (200 mg total daily) demonstrated more potent anti-anginal effect than propranolol 80 mg twice daily (160 mg total daily) 2
Pharmacokinetic Considerations
Atenolol has a significantly longer half-life (5-8 hours) compared to immediate-release propranolol (3-6 hours), allowing for once-daily dosing versus multiple daily doses for propranolol 3, 4
Atenolol is hydrophilic with minimal CNS penetration (0-5% protein binding), while propranolol is highly lipophilic (85-95% protein binding), resulting in significantly fewer CNS side effects with atenolol at equivalent therapeutic doses 3, 5
The bioavailability of atenolol is 50-60%, while propranolol immediate-release is 20-50%, but this difference is accounted for in the dosing equivalency 3
Recommended Conversion Protocol
Initial Conversion Strategy
Start with atenolol 50 mg once daily when converting from propranolol 80 mg daily 1
If the patient was taking propranolol 80 mg twice daily (160 mg total), consider starting atenolol 50-100 mg once daily 1, 2
Atenolol should be administered once daily, preferably in the morning, due to its longer half-life 3
Monitoring After Conversion
Check blood pressure and heart rate within 1-2 weeks after conversion to assess therapeutic response 3
Target resting heart rate of 50-60 beats per minute unless limiting side effects occur 6
Monitor for signs of inadequate beta-blockade (increased angina frequency, uncontrolled hypertension) or excessive beta-blockade (symptomatic bradycardia, hypotension) 6
Important Clinical Differences Between Agents
Cardioselectivity Advantage
Atenolol is cardioselective (β1-selective), while propranolol is non-selective (β1 and β2), making atenolol safer in patients with mild reactive airway disease or peripheral vascular disease 2, 5
This cardioselectivity is maintained at therapeutic doses but is lost at very high doses 3
Side Effect Profile
CNS side effects (fatigue, depression, sleep disturbances) are significantly less common with atenolol compared to propranolol at equally effective antihypertensive doses 5
A comparative study showed definite improvement in CNS side effect severity scores during atenolol treatment versus propranolol in patients with prior beta-blocker side effects 5
Renal Considerations
Atenolol is primarily renally eliminated (85% unchanged in urine), requiring dose adjustment in renal impairment, while propranolol is hepatically metabolized 3
In patients with significant renal dysfunction (CrCl <35 mL/min), atenolol dose should be reduced by 50% or propranolol may be preferred 3
Common Pitfalls to Avoid
Do not assume 1:1 dose equivalency - propranolol requires higher doses than atenolol for equivalent effect 1
Avoid abrupt discontinuation of propranolol before starting atenolol - taper propranolol over several days while initiating atenolol to prevent rebound hypertension or angina exacerbation 7
Do not use atenolol in patients with severe renal impairment without dose adjustment, as it accumulates significantly 3
In patients with diabetes, both agents can mask hypoglycemia symptoms, but atenolol's cardioselectivity may offer slight advantage 7, 8
Special Population Considerations
For elderly patients or those with multiple comorbidities, start with the lower end of the dose range (atenolol 25-50 mg daily) and titrate based on response 6
In patients with heart failure with reduced ejection fraction, metoprolol succinate is preferred over both propranolol and atenolol for mortality benefit 6
For performance anxiety or situational use, propranolol's shorter half-life and CNS penetration may actually be advantageous, making atenolol less suitable for this specific indication 7