Objective: Verification of knowledge of the character and frequency of untoward effects in connection with the application of omeprazol (Helicid Léčiva, capsules) under routine administration in practice on a large group of patients. Methods: In a series of 8109 patients there has been studied the safety profile of a registered product (omeprazol - Helicid Léčiva, capsulea) in routine practice. 198 physicians participated in the study. On the average the overall period of follow-up of a patient was 176 days; three visits of the patient took place (initial, control, final) with notes in a questionnaire. However, in some cases the questionnaire was not filled in completely. The patients were treated with omeprazol in generally valid indications: peptic ulcer, reflux esophagitis, and gastropathy induced by non-steroidal antirheumatics drugs. The mean age of the patients was 53.8 (ranging 10-99 years).The series comprised 3748 females,average age 55.7 (10-99 years),and 4220 males, average age 52.2 (14-96 years); in 141 patients gender had not been noted. Results: In the course of the follow-up, adverse drug reactions have been reported in 20 patients representing 0.25 % of the whole series of 8109 patients. In all, there have been reported 25 adverse drug reactions (nausea, diarrhea, flatulence, headache, rash, allergic skin exanthema, pruritus, reflux symptomatology following eradication therapy, arthralgias, edema in the eyelids). None of the reactions were serious. In 19 patients the adverse drug reaction faded away without sequlae, in 1 patient the fate of the reaction remains unknown. Out of these 20 patients the adverse drug reaction led to termination of therapy in 10 cases, in 9 cases therapy continued, and in 1 that was not specified. 16 side-effects fell in the category of expected reactions, the remaining 9 were unexpected. Conclusion: The safety of omeprazol (Helicid Léčiva, capsules) was assessed on the basis of the occurrence of untoward effects. In the series under follow-up, 25 unexpected adverse drug reactions have been reported in 20 patients, that representing only 0.25 % out of a total of 8109 patients. The health status was rated by physicians as „improved“ in 90.6 % of the patients on the first control examination, and in 76.6 % at the final one. Reckoning the size of the series and the number of reported adverse drug reaction, also in view of their type and significance, it can be stated that the drug can continue to be considered as well tolerated.

        Key words: gastroscopy - proton pump inhibitor - omeprazol - adverse drug reaction.