Major
Bisoprolol × clonidine
Selective beta-adrenergic blockers×Central α2-adrenergic agonist
Mechanism
Abrupt clonidine withdrawal on a beta-blocker triggers a hypertensive crisis: the α2 effect is lost while β-blockade persists – an 'unopposed' α1 effect develops with a sharp blood pressure rise.
Symptoms
Abrupt clonidine withdrawal causes hypertensive crisis: sharp blood pressure rise, headache, tachycardia, anxiety, sweating. Symptoms appear 18–24 hours after a missed clonidine dose.
Management
For planned clonidine withdrawal, stop bisoprolol 3–7 days beforehand, then taper clonidine over 1–2 weeks. Alternative antihypertensives: an ACE-I (enalapril) plus amlodipine without clonidine.