A randomised controlled trial of the monoaminergic stabiliser (-)-OSU6162 in treatment of ME/CFS (2017) Nilsson et al.

I revisited this paper with recent insights into apipiprazole (Abilify) in mind. Both OSU6162 and Abilify are dopamine system stabilisers that also exercise serotonergic effects. They work as partial agonists on some of the same receptor subclasses. If I have my facts straight, both were originally developed to treat schizophrenia.

A couple of things about the OSU6162 trial jumped out at me.

First there's dosage. Gottfries and colleagues had patients build up to the OSU "schizophrenia dosage" of 30mg/day. Which was great for establishing the safety of OSU6162 in MECFS but less than ideal from a treatment standpoint.

Schizophrenia is thought to be characterised by dopamine excess. Like Abilify for schizophrenia, the comparatively large dosage of OSU aims to "bat away" the excess and guarantee a steady signal. By contrast, dopamine drought is thought to occur in MECFS so there's no need for such high doses.

As others have pointed out, this clinical trial spanned only two weeks. This short timeframe is extra jarring in light of what we (think we now) know about Abilify in MECFS, ie. that beneficial effects tend to become apparent *from* approx. 2 weeks onwards after starting low and going slow as the drug concentration reaches a steady state. I've not closely investigated the exact pharmacological properties of OSU6162, perhaps it works similarly.

Long story short, I'd love to see a variation of this trial happen, double-blinded once more with strict CCC patient selection, but this time employing OSU6162 doses of up to max. 2mg/day for a duration of 8 weeks. This can't be difficult to set up, can it?

Edit: I completely missed this 2021 open label study by the same group! They're still working on OSU6162 for MECFS; I'm relieved.

 

According to the interviews with Arvid Carlsson I've read (here and here, for example), OSU6162 was first tested in l-dopa dyskinesia and Huntington's disease.

His company Carlsson Research also developed the antipsychotic ACR16 (Huntexil), which has sometimes been compared to Abilify.

 

I see. Good to know!