45. Atenolol – high BP

 

. Mechanism & Class

• Class: Cardioselective β₁-blocker

• Action:

  • Blocks cardiac β₁-receptors → ↓ heart rate, ↓ contractility, ↓ renin release

  • Reduces cardiac output → lowers BP

• Key Limitation:

  • Lacks vasodilatory effects (unlike carvedilol/nebivolol)

  • Minimal CNS penetration (vs. propranolol)

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2. FDA-Approved Uses

Indication	Dosage Range	Notes
Hypertension	25-100 mg daily	Not first-line per guidelines
Angina Pectoris	50-200 mg daily	Reduces attack frequency
Arrhythmias	50-100 mg daily	SVT/Ventricular control

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3. Dosing Protocol

• Starting: 25-50 mg once daily

• Titration: ↑ by 25 mg weekly (max 100 mg/day)

• Take: On empty stomach (food ↓ absorption 20%)

• Renal Adjustment:

  CrCl (mL/min)	Dose Adjustment
  15-35	Max 50 mg/day
  <15	Max 25 mg/day or avoid

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4. Black Box Warnings & Contraindications

Risk	Critical Considerations
Abrupt Withdrawal	↑ Angina/MI risk – taper over 1-2 weeks
Heart Failure Decompensation	Avoid in acute HF or HFrEF (NYHA IV)
Absolute Contraindications	• Asthma/COPD (relative) • Heart block >1st degree • Cardiogenic shock

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5. Adverse Effects

Common (>10%)	Serious (<1%)
Fatigue	Bradycardia (<45 bpm)
Cold extremities	Heart block
Sexual dysfunction	Masked hypoglycemia (diabetics)
Metabolic: ↑ TG, ↓ HDL-C, insulin resistance

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6. Modern Role in Hypertension

• ❌ Not recommended as first-line monotherapy per ACC/AHA 2023 guidelines:

  • Inferior stroke prevention vs. ARBs/CCBs (LIFE trial)

  • ↑ Diabetes risk by 28% (ASCOT trial)

• ✅ Consider when:

  • Coexisting angina or tachyarrhythmias

  • Post-MI patients (if no HF)

  • Pregnancy (Category C)

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7. Drug Interactions

Interacting Drug	Risk	Action
Verapamil/Diltiazem	↑ Bradycardia/AV block	Avoid combo
Insulin/Sulfonylureas	Masked hypoglycemia	Educate diabetic patients
NSAIDs	↓ Antihypertensive effect	Monitor BP

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8. Clinical Pearls

• Elderly: ↑ Risk of bradycardia – start at 12.5 mg/day

• Diabetics: Avoid – worsens glycemic control; use carvedilol/nebivolol

• Pregnancy: Safer than ACEi/ARBs but less effective than labetalol

• Cocaine-Induced HTN: Contraindicated (unopposed α-vasoconstriction)

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🆚 Atenolol vs. Newer Beta-Blockers

Parameter	Atenolol	Carvedilol	Nebivolol
Vasodilation	None	α-blockade	NO-mediated
Metabolic Effects	Worsens insulin resistance	Neutral	Improves insulin sensitivity
HFrEF Mortality	No benefit	Proven ↓ mortality	Proven ↓ mortality
Guideline Status	Deprecated	Preferred	Preferred

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9. Patient Counseling

1. "Never stop suddenly – taper over 2 weeks."

2. "Check pulse daily – hold dose if <55 bpm."

3. "Diabetics: Monitor glucose closely – hides low sugar symptoms."

4. "Report: Shortness of breath, ankle swelling, dizziness."

5. "Avoid decongestants (e.g., pseudoephedrine)."

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⚠️ Red Flags:

• Heart rate <50 bpm → reduce/stop dose

• New dyspnea/edema → evaluate for heart failure

Sources: ACC/AHA Hypertension Guideline (2023), LIFE Trial (Lancet), NICE Guidelines (2023).
Prescribing Insight: Reserve for specific scenarios like angina with HTN – not routine hypertension management.