Objective: Paracetamol is a pharmacological agent with a wide spectrum of use as an analgesic and antipyretic. This wide use may affect many systems, including the gastrointestinal system. Previous studies have shown that paracetamol exhibits inhibitory activity on uterine and bladder smooth muscles, and it is thought that this activity may also affect the smooth muscles of the gastrointestinal system, namely the jejunum and ileum. So,the main aim of this study was to investigate the possible in vitro activity of paracetamol on the spontaneous contraction of jejunum and ileum smooth muscles.

Materials and Methods: Jejunum and ileum strips (10x3x1 mm) removed from intact female Sprague-Dawley rats in diestrus phase were suspended in isolated organ baths under 1 gram tension (n=7). After regulation of spontaneous contractions, paracetamol was added non-cumulatively at doses of 1 mM and 2 mM. Peak-to-peak (p-p),area under the curve (AUC),and maximum contraction values (Emax) obtained before and after these applications were standardized as % change. The data were analyzed using Paired Sample T-test and to compare the data obtained from different administered doses, Independent Samples T-test was used for analysis in SPSS 22.0 software.

Results: Paracetamol administration at 1 mM and 2 mM doses caused a statistically significant decrease in Emax, p-p, and AUC values in both jejunum and ileum smooth muscle spontaneous contractions (p<0.05).

Conclusions: Paracetamol administration has a dose-dependent inhibitory effect on jejunum and ileum smooth muscle spontaneous contraction. It could be clinically important to consider this effect when using paracetamol in individuals with gastrointestinal system pathologies.