I have been taking Ranitidine since my early teens some 20 yrs + and have recently been prescribed varying pain medication from an injury stustained whilst falling down a set of stairs. It was only after trying non opioid medication and surgery to no great affect that I was prescribed Oxycontin SR. Regardless of the dosage the Oxyconting SR is designed to remain active for 12hours but I have been getting a maximum of 6-8 hrs relief. My surgeon and general practinitioner are at a loss and was wondering if it had something to do with the Ranitidine. As it reduced the amount of stomach acid preduced could it be possible that with reduced stomach acid to dissolve the SR Tablet, my boody is passing it through my digestive tract before it has time to fully dissolve in turn providing the 12 hour relief. I would greatly appreciate any advice.