Drug interactions in gastrointestinal disorders therapy

Drug-drug interactions are a major cause of adverse reactions in polypharmacy, the incidence being directly proportional to the number of associated drugs. In this work, we highlighted the main drug-drug interactions that occurred in the treatment of gastrointestinal symptoms with proton pump inhibitors and histamine H2-receptor antagonists. The two groups of agents, used in gastroesophageal reflux and ulcer disease, can be released and without a prescription on the recommendation of the pharmacist, contributing to the risk of emergence of drug-drug interactions. Drug-drug interactions can occur due to the reduction of the gastric acidity, altering the biotransformation or excretion reducing of the drug co-administrated. pH increased may affect the absorption of some drugs decreasing (e.g. ketoconazole, itraconazole, atazanavir, vitamin B12, magnesium) or increasing the absorption of others (e.g. triazolam, midazolam). Furthermore, an attention to the interaction with narrow therapeutic index drugs (e.g. warfarin, phenytoin, theophylline) is required because of the risk of the toxic or side effects by the accumulation of these drugs.