Tried name-brand Zantac OTC 150-mg in blister packs bought at Walmart in making the recommended switch from Nexium 40 mg (proton pump inhibitor). It worked well for 3 weeks. Then bought name-brand Zantac OTC 150-mg in a bottle at Costco and I almost immediately started with breakthrough reflux. The first pill was more coral-colored, the other brighter pink. One seemed to be made by Glaxo, the other by Pfiser even though they were supposedly brand name. Do these two Zantac forms enter the body through different administrative pathways so that one might be less effective than the other in certain people? Or might the second contain defective pills?