Pilot Study of Pramipexole for Anhedonia Symptoms in Unipolar Depression
At a recent scientific meeting, researcher Laura Hack described an open-label pilot study of pramipexole in participants with major depression including anhedonia, or inability to feel pleasure. Five participants with prominent anhedonia and major depression completed eight weeks of treatment with pramipexole, which activates dopamine D2 and D3 receptors. Four of the five who completed the study saw notable improvements in their anhedonia and quality of life.
The starting daily dose was 0.26 mg, which was increased every three days to a target dose of 2.0 mg per day. Two additional patients dropped out due to side effects (nausea, poor sleep, and headache).
Low activity in the ventral striatum, a part of the brain associated with decision-making and implicated in the brain’s reward system, correlated with the severity of the patients’ anhedonia. These results suggest that further studies are warranted.
Pramipexole has also shown positive effects in two small studies in bipolar depression. The drug is currently approved by the US Food and Drug Administration for the treatment of Parkinson’s disease and also works in restless legs syndrome.
A Novel Drug Shows Promise in the Treatment of Negative Symptoms of Schizophrenia
At a recent scientific meeting, Kenneth Koblan, Chief Scientific Officer at Sunovion Pharmaceuticals, Inc. reported on a new drug in development, SEP-363856, and its effects on negative symptoms of schizophrenia.
In both a 4-week double-blind study of participants with acute schizophrenia and in an open (non-blind) 6-month extension study, SEP-363856 was effective on negative symptoms. In the placebo-controlled acute study, those randomized to 50mg or 75mg of the drug showed improvement of moderate effect size in the following symptoms: blunted affect, avolition, anhedonia, asociality, and alogia. In the extension study, which consisted of 26 weeks of treatment with flexible doses (25/50/75 mg/day) of SEP-365846, patients improved further on multiple scales measuring negative symptoms.
SEP-363856 is a novel trace amine receptor 1 (TAAR1) agonist with serotonin 5-HT1A activity. Koblan and colleagues concluded, “These results suggest that activation of the TAAR1 receptor by SEP-363856, in the absence of D2 receptor blockade, may represent a promising approach to the treatment of negative symptoms in schizophrenia.”
