Contraindicated w/ MAOIs & antidepressants which affect noradrenergic transmission (eg, TCAs & mianserin). TCAs may blunt the ocular hypotensive response. Additive or potentiating effect w/ CNS depressants (eg, alcohol, barbiturates, opiates, sedatives or anaesth). Use w/ caution in patients taking drugs affecting metabolism & uptake of circulating amines (eg, chlorpromazine, methylphenidate, reserpine, SNRIs). Reduced pulse & BP w/ concomitant use of antihypertensives & cardiac glycosides. Use w/ caution when initiating concomitant adrenergic receptor agonists or antagonists eg, isoprenaline, prazosin. Additive effect on known systemic effects of carbonic anhydrase inhibition w/ oral carbonic anhydrase inhibitor. Inhibited metabolism w/ CYP3A4 inhibitors (eg, ketoconazole, itraconazole, clotrimazole, ritonavir & troleandomycin).