Deborah Brauser

October 09, 2013

BARCELONA, Spain ― The long-acting histamine H2-receptor antagonist famotidine may decrease symptoms of treatment-resistant schizophrenia, new research suggests.

A small, randomized controlled trial (RCT) of patients in Finland with this type of disorder showed that those who received a high dose of famotidine for 4 weeks had significantly greater reductions in symptom scores compared with the participants who received matching placebo.

In fact, the overall symptom reduction for the famotidine group at the end of the study was approximately 10% vs "virtually no change" in the placebo group.

"We're very excited about the findings," lead author Katarina Meskanen, from the Department of Psychiatry at the University of Helsinki in Finland, told Medscape Medical News.

"Not to draw too many conclusions, but we're suggesting that the H2 has some effect on psychosis. And this is garnering some significant interest," she added.

The investigators note that this is the first placebo-controlled RCT to show a significant benefit from a histamine H2 blocker on treatment-resistant schizophrenia ― and that the effect was "clinically relevant."

"Our results suggest that a H2 receptor antagonist has antipsychotic properties and may provide a new potential pharmacological approach to the treatment of patients with schizophrenia who have not responded well enough to presently available treatments," they write.

The study was presented here at the 26th European College of Neuropsychopharmacology (ECNP) Congress.

Understudied

"Histamine has received relatively little attention in clinical studies of psychiatric disorders even though it has important functions as a regulator of several key neurotransmitters," write the researchers.

"The most direct human data on the role of histamine in psychosis shows that patients with schizophrenia have lower histamine H1 receptor levels."

They add that in 1990, a case report was published that showed benefits of famotidine for treating schizophrenia's negative symptoms. Since then, however, only a few open-label trials have been conducted that have assessed this H2-receptor antagonist.

Katarina Meskanen

"So we wanted to do a better study, an RCT," said Meskanen.

For this trial, the investigators enrolled 30 patients from Helsinki with treatment-resistant schizophrenia and a high level of accompanying symptoms. All were randomly assigned to receive for 4 weeks either 100 mg of oral famotidine twice daily (n = 16) or matching placebo (n = 14).

The study drugs were added to the patients' normal treatment regimen. There was also a 1-week placebo run-in before randomization, and a 1-week washout before the last assessment.

The primary outcome measure was change on the Scale for the Assessment of Negative Symptoms (SANS).

Secondary measures included the Positive and Negative Syndrome Scale (PANSS) and the Clinical Global Impression scale (CGI).

Significant Secondary Outcomes

Results showed that the primary outcome measure did not reach statistical significance.

Although the group receiving famotidine showed a mean SANS score that decreased between baseline and last assessment by 5.3 points, and the placebo group showed a score that actually increased by 0.2 points, the P value was 0.13.

On the other hand, all secondary measures did reach significance. The mean PANSS total score for the famotidine group decreased by 9.1 points vs a decrease of 0.6 points for the placebo group (P = .04). PANSS general scores decreased by 4.6 and increased by 0.4, respectively (P = .02).

The mean CGI score was also significant in the patients receiving the study drug vs those receiving placebo (P = .001).

"It is noteworthy that the reduction of symptoms started from the baseline measurement and was consistent all the way to the endpoint," write the investigators. However, they note that more research is now needed.

Meskanen reported that they are now planning to replicate this study ― but will use the PANSS as the primary outcome measure.

"It's much more sensitive to change," she explained. "We'll be enrolling 70 patients in Finland and 70 in Sweden. So it'll be larger and will have a longer randomization phase."

New Treatment Option?

"This poster suggests that antihistamine drugs may be beneficial in the future treatment of this disorder, especially for negative symptoms. So it may potentially be a good option," Abdullah Cem Sengul, MD, associate professor in the Department of Psychiatry at Pamukkale University School of Medicine in Denizli, Turkey, told Medscape Medical News.

Dr. Sengul, who was not involved with the research, also noted that "it would be nice" to have an intervention with a different mechanism of action.

"Every patient deserves the right treatment, so it will be good to have more options and more choices for them ― especially when it comes to schizophrenia," he said.

The study was funded by the Medical Society of Finland, the Helsinki University Central Hospital Research Fund, and the Lilly Foundation. The study authors have disclosed no relevant financial relationships.

26th European College of Neuropsychopharmacology (ECNP) Congress. Abstract P.3.d.006. Presented October 8, 2013.

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