Therabloc Drug Interactions

Because of reserpine's catecholamine-depleting activity, concomitant administration of atenolol with reserpine may increase the incidence of hypotension and bradycardia compared to atenolol alone.
Atenolol has a synergistic blood pressure-lowering effect when given in combination with dihydropyridine calcium-channel blockers (ie, nifedipine). However, its combination with nondihydropyridine calcium-channel blockers (ie, verapamil, diltiazem) is not advisable because such a combination may excessively depress heart rate and cardiac function.
β-Blockers may exacerbate the rebound hypertension that may follow after withdrawal from clonidine. If the 2 drugs are concomitantly administered, the β-blocker should be withdrawn several days before the gradual withdrawal of clonidine. In replacing clonidine with β-blocker therapy, the introduction of β-blockers should be delayed for several days after clonidine administration has stopped.