Codeine and olopatadine intranasal equally increase sedation. Steer clear of or Use Alternate Drug. Coadministration improves chance of CNS despair, which can cause additive impairment of psychomotor performance and bring about daytime impairment. cimetidine will enhance the level or effect of codeine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Watch. https://wockusa.com/product/copyright-crystals/