<p>Although specific drug interaction studies have not been conducted with Brimonidine Tartrate ophthalmic solution 0.2%, the possibility of an additive or potentiating effect with CNS depressants (alcohol, barbiturates, opiates, sedatives, or anesthetics) should be considered. Alpha-agonists, as a class, may reduce pulse and blood pressure. Caution in using concomitant drugs such as beta-blockers (ophthalmic and systemic), antihypertensives and/or cardiac glycosides is advised. Tricyclic antidepressants have been reported to blunt the hypotensive effect of systemic clonidine. It is not known whether the concurrent use of these agents with Brimonidine Tartrate ophthalmic solution 0.2% in humans can lead to resulting interference with the IOP lowering effect. No data on the level of circulating catecholamines after administration of Brimonidine Tartrate ophthalmic solution 0.2% are available. Caution, however, is advised in patients taking Tricyclic antidepressants which can affect the metabolism and uptake of circulating amines.</p>