Cosopt/Cosopt-S Drug Interactions

Specific drug interaction studies have not been performed with Cosopt/Cosopt-S.
In clinical studies, Cosopt/Cosopt-S was used concomitantly with the following systemic medications without evidence of adverse interactions: ACE inhibitors, calcium-channel blockers, diuretics, nonsteroidal anti-inflammatory drugs including aspirin and hormones (eg, estrogen, insulin, thyroxine).
However, the potential exists for additive effects and production of hypotension and/or marked bradycardia when timolol maleate ophthalmic solution is administered together with oral calcium-channel blockers, catecholamine-depleting drugs or β-adrenergic-blocking agents.
Potentiated systemic β-blockade (eg, decreased heart rate, depression) has been reported during combined treatment with CYP2D6 inhibitors (eg, quinidine, selective serotonin reuptake inhibitors) and timolol.
The dorzolamide component of Cosopt/Cosopt-S is a carbonic-anhydrase inhibitor and although administered topically, is absorbed systemically. In clinical studies, dorzolamide HCl ophthalmic solution was not associated with acid-base disturbances. However, these disturbances have been reported with oral carbonic anhydrase inhibitors and have in some instances, resulted in drug interactions (eg, toxicity associated with high-dose salicylate therapy). Therefore, the potential for such drug interactions should be considered in patients receiving Cosopt/Cosopt-S.
Oral β-adrenergic blocking agents may exacerbate the rebound hypertension which can follow the withdrawal of clonidine.