AntacidsMagnesium HydroxideAluminum HydroxideSimethiconeMagnesium OxideSilicic AcidCalcium CarbonateHeartburnHistamine H2 AntagonistsDrug CombinationsRanitidineSodium BicarbonateCimetidineSiliconesDrug InteractionsEsophagitis, PepticDuodenoscopyFood-Drug InteractionsGastric Acidity DeterminationTechnetium Tc 99m PyrophosphateBiological AvailabilityFamotidineDosage FormsAnti-Ulcer AgentsCarbonatesSucralfateAlginatesDimethylpolysiloxanesEnoxacinGastroesophageal RefluxGastric AcidPneumonia, AspirationCross-Over Studies