<p>Additive hypotension and bradycardia with oral calcium channel blockers, catecholamine-depleting drugs or &beta;-blockers, antiarrhythmics (e.g. amiodarone), digitalis glycosides, parasympathomimetics, narcotics and MAOIs. Additive systemic side effects with oral carbonic anhydrase or &beta;-blockers; avoid concurrent use. Additive systemic &beta;-blockade with CYP2D6 inhibitors (e.g. quinidine, SSRIs) and timolol.</p>