A randomized clinical trial indicated that add-on baclofen may be of benefit to patients on adequate doses of proton pump inhibitors (PPI) with refractory gastroesophageal reflux disease (GERD). However, the benefit was limited to a subset of patients with positive symptom association probability (SAP), which was calculated using 24-hour combined multichannel intraluminal impedance and pH monitoring (24h pH-MII).
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“Empirical add-on therapy with baclofen in GERD patients with persisting typical symptoms in spite of double-dose PPI therapy does not seem justified. The use of baclofen should be limited to patients who display a positive SAP for typical reflux symptoms (heartburn and/or regurgitation) during PPI therapy,” researchers led by Ans Pauwels, PhD, MPharmSc, of the Catholic University of Leuven (Belgium) concluded in Alimentary Pharmacology & Therapeutics.
Asked to comment, Philip Katz, MD, professor of medicine and director of GI Function Laboratories at Weill Cornell Medicine and a co-author of some recent GERD guidelines said, “What it tells me is that baclofen may be useful to a patient population that has an accurate diagnosis of reflux hypersensitivity. The difficulty with this study is that the patients you would expect to be helped by baclofen, which were patients who satisfied the criteria for true GERD, didn’t have any improvement.”
PPIs are effective at reducing acid reflux and promoting esophageal healing in GERD patients, but they have little effect on non-acid reflux. Heartburn is most often tied to acid reflux, but regurgitation occurs with similar frequency during both acid and non-acid episodes.
Up to 50% of patients still have reflux despite PPI treatment, and many of these patients will respond to higher PPI doses. However, those who don’t respond are left with few treatment choices.
Reflux events generally occur during transient lower esophageal sphincter relaxations (TLOSRs), and this mechanism is predominant in mild and moderate GERD. A gamma-aminobutyric acid type B receptor agonist, baclofen reduces TLOSRs and associated reflux episodes following meals. Few studies have examined the clinical potential of baclofen in refractory GERD, and it generally is only used after determining that ongoing weakly acidic reflux is responsible for symptoms, using 24h pH-MII.
The study included about 60 patients who underwent 24-hour monitoring while taking a PPI twice daily. Over a 2-week run-in period, participants filled out daily diaries and were randomized to placebo or baclofen 3 times daily over 4 weeks. The baclofen dose was 5 mg for the first week, then 10 mg for the next 3 weeks.
At the end of treatment, 24h pH-MII was repeated. The researchers found no significant decreases in non-acid reflux events after placebo treatment (corrected P = .74) and a trend towards a reduction following baclofen treatment (corrected P = .12).
Although the results won’t change his practice significantly, Dr. Katz congratulated the authors on the thoroughness of the study. However, he noted that wellbeing is a difficult endpoint to study: “The importance of this study to me is that it confirms that baclofen shouldn’t be used empirically, since there was no improvement in patients who were functional, and it was hard to find improvement in any group. This reinforces the need for a thorough work-up of the patient with GERD.”
The drug also had some tolerability issues: 16% of patients on baclofen discontinued its use because of adverse events such as drowsiness, dizziness, headache, and nausea.
An important limitation of the study is that the researchers recruited patients with persistent GERD symptoms despite use of PPIs. “Calling it refractory GERD is tricky because they didn’t prove they had GERD before they were enrolled in the study. That being said, the researchers did a very rigorous, very careful study to try and find potentially some place that baclofen might benefit patients,” said Dr. Katz.
The authors of the study and Dr. Katz have no relevant financial disclosures.