Effect of the GABAB agonist baclofen in patients with symptoms and duodeno-gastro-oesophageal reflux refractory to proton pump inhibitors

Background and aims: A subset of patients with gastro-oesophageal reflux disease (GORD) with refractory symptoms during therapy with proton pump inhibitors (PPIs), have persistent non-acid duodenogastro-oesophageal reflux ( duodenal reflux). The aim of the present study was to investigate the effect of the GABA(B) receptor agonist baclofen, which was shown to inhibit the occurrence of transient lower oesophageal sphincter relaxations (TLOSRs) in patients with persistent non-acid duodenal reflux during PPI therapy. Methods: Patients were eligible for the study if they had persistent reflux symptoms, normal pH monitoring, and pathological Bilitec monitoring during PPI treatment. Upper gastrointestinal endoscopy and reflux symptom score were performed at the beginning of the study. Baclofen 5 mg three times daily was associated with treatment, and was increased by 5 mg every fourth day until a maintenance dose of 20 mg three times daily was reached. A reflux symptom questionnaire, ambulatory pH monitoring, and Bilitec monitoring were repeated four days later while PPI and baclofen were continued. All data are given as mean (SEM) or median (interquartile range) and were compared using the Student's t test or the Mann-Whitney U test. Results: Sixteen patients ( 11 women, mean age 46 ( 3) years) with persistent heartburn or regurgitation for at least three months, in spite of PPI therapy, were included in the study. Erosive oesophagitis was present in seven patients ( five with grade 1, two with grade 2). Under PPI therapy alone, all patients had normal acid exposure (0.3 (0.05; 2.2)% of the time) but pathological duodenal reflux exposure (13.8 (11.8; 15.5)% of the time). After addition of baclofen 20 mg three times daily, acid exposure was similar (0.4 (0.15; 2.3)% of the time; NS) but duodenal reflux had significantly decreased (6.1 ( 0.8; 10.3)% of the time; p< 0.05). The number of duodenal reflux episodes and the number of longlasting duodenal reflux episodes (> 5 minutes) was decreased, respectively, from 23 (14.5; 34) to 12 ( 5; 21) ( p = 0.06) and from 5 ( 3; 8) to 2 (0.5; 4.5) ( p< 0.05). The cumulative severity score for 14 reflux symptoms decreased from 10.3 (1.7) to 5.8 ( 1.3) ( p< 0.01). Four patients reported mild side effects of nausea or drowsiness. Conclusions: The GABA(B) receptor agonist baclofen improves duodenal reflux and associated reflux symptoms that persist during PPI therapy.