Pharmacology · Year 2 · from Pharmacology
Case 3: Beta-Blocker Withdrawal Syndrome (Receptor Upregulation)
Clinical Scenario
A 55-year-old male presents with chest pain, palpitations, and severe hypertension 48 hours after abruptly stopping his metoprolol.
Patient Demographics
- Age: 55 years
- Sex: Male
- Weight: 90 kg
Chief Complaint
Chest tightness, racing heart, and severe headache for 12 hours
History of Present Illness
The patient has a history of hypertension and stable angina, controlled on metoprolol succinate 200 mg daily for 8 years. He ran out of medication 3 days ago and could not get a refill due to a pharmacy issue. Over the past 48 hours, he has developed progressive chest tightness, palpitations, anxiety, diaphoresis, and severe headache.
Physical Examination
- Vital Signs: BP 210/115 mmHg, HR 118 bpm, RR 22, T 37.1C
- General: Anxious, diaphoretic
- Cardiovascular: Tachycardic, regular, no murmurs, hyperdynamic precordium
- Neurological: Alert, oriented, no focal deficits
- HEENT: Pupils dilated, no papilledema on fundoscopy
Workup and Results
| Test | Result | Reference Range |
|---|---|---|
| Troponin I | 0.08 ng/mL | <0.04 ng/mL |
| BNP | 320 pg/mL | <100 pg/mL |
| Creatinine | 1.0 mg/dL | 0.6-1.2 mg/dL |
| TSH | 2.1 mIU/L | 0.4-4.0 mIU/L |
ECG: Sinus tachycardia at 118 bpm, 1 mm ST depression in leads V4-V6
Diagnosis
Beta-blocker withdrawal syndrome with rebound hypertension, tachycardia, and demand ischemia due to receptor upregulation
Pharmacodynamic Principles Illustrated
- Receptor upregulation: Chronic beta-blockade leads to increased beta-receptor density and sensitivity as a compensatory mechanism.
- Rebound phenomenon: Abrupt discontinuation unmasks the upregulated receptors, causing exaggerated response to circulating catecholamines.
- Tolerance and dependence: These are physiological adaptations distinct from addiction.
- Tapering requirement: Gradual dose reduction over 1-2 weeks allows receptor normalization.
Treatment
- Immediately restart beta-blocker (IV metoprolol 5 mg, repeat as needed)
- Aspirin and heparin for possible ACS
- IV nitroglycerin for persistent hypertension and angina
- Continuous cardiac monitoring
- Serial troponins and ECGs
- Once stabilized, ensure adequate outpatient supply and education about never stopping abruptly
Key Learning Points
- Beta-blocker withdrawal is a medical emergency in patients with coronary disease
- Can precipitate acute coronary syndrome, arrhythmias, or hypertensive crisis
- Always taper beta-blockers over 1-2 weeks when discontinuing
- Patients should be educated never to stop abruptly and to have adequate medication supply