Evaluation of the effect of pantoprazole on serotonin secretion and metabolism in patients with functional dyspepsia

Introduction: Pantoprazole, in general, is a well-tolerated drug. Among rarely occurring adverse drug reactions there are headaches, dizziness, muscular pains, rush, nausea, diarrhoea or constipation and dystymia or even depression. The character of these untoward symptoms makes us suspect that serotonin and histamine may play a role in their pathogenesis. Aim: The study aimed at evaluating the effect of pantoprazole on serotonin secretion and metabolism in patients with functional dyspepsia (FU). Material and methods: The study was conducted on 40 patients with functional dyspepsia, at the age of 20 – 47 years (mean age 34,8 years). According to Rome III Criteria in 20 patients postprandial distress syndrome (PDS) was diagnosed and in further 20 – epigastric pain syndrome (EPS). The control group constituted of 20 healthy persons. The study was conducted on two consecutive days – on the first day without pantoprazole and on the following day after the oral administration of pantoprazole 40 mg bid. On the days of the evaluations the studied subjects were given standard meals in the form of Nutridrinks (Nutricia) in the amount of 400 ml three times a day (1800 kcal/24h). The blood samples were drawn two hours after the first meal. On the second day of the study antoprazole was administered orally prior the first and the third meal. At the same time 24-hour urine collection was conducted. Serotonin serum concentration and 5-hydroxyindolic acid (5-HIAA) concentration in urine were measured applying the immunoenzymatic method with the use of IBL antibodies (the catalogue numbers - RE 59121 and RE59131). Results: Postprandial serotonin concentration in the healthy persons was 142,4 + 26,7 ng/ml, in the patients with PDS – 151,6 + 29,0 ng/ml (p > 0,05) and in EPS – 231,6 + 35,9 ng/ml (p < 0,01). On the second day of the study after pantoprazole administration serotonin serum concentration decreased to 205,6 + 31,9 ng/ml (p < 0,01) in EPS, but it did not change in PDS. 5-HAA excretion after pantoprazole intake decreased in both clinical forms of functional dyspepsia – in PDS from 3,55 + 1,14 mg/24h to 3,20 + 1,16 mg/24h (p < 0,05) and in EPS from 5,70 + 1,89 mg/24h to 4,51 + 1,46 mg/24h (p< 0,01). Conclusions: Single doses of pantoprazole decrease postprandial secretion of serotonin only in patients with EPS. 24-hour urinary 5-HIAA excretion after pantoprazole decreases in both types of functional dyspepsia (PDS and EPS). (Clin Exp Med Lett 2009; 50(3):169-173)

Keywords: pantoprazole, functional dyspepsia, postprandial distress syndrome, epigastric pain syndrome, Serotonin, 5-hydroxyindolic acid.