Histamine H2 Antagonism as Adjuvant Therapy in Treatment Resistant Schizophrenia

Histamine functions as a neurotransmitter in the brain. It has an important role as modulator of the release of other neurotransmitters, including dopamine. The histamine receptors are widely expressed in the brain, H1 and H2 receptors are post-synaptic, H3 a pre-synaptic autoreceptor. There is an abundance of neurobiologic data from animal and human studies supporting the role of histamine in the pathogenesis and treatment of psychoses. In 1990 a case report of a treatment resistant subject with schizophrenia whos symptoms improved markedly when he was prescribed a H2 antagonist because of peptic ulcer. Later, a open-label trial including 18 patients has been performed, reporting significant symptom reduction, especially on negative symptoms. Also the subjective comments both by the subjects and the investigators in that study were optimistic and suggested an effect primarily on negative symptoms. The present study will be the first double-blind, randomized, placebo controlled, parallel group study of the subject matter. The study focuses on treatment resistant schizophrenia cases in the stable phase.