**5.3.23 Dexpramipexole (R-(+) pramipexole; RPPX; KNS-760704)**

Dexpramipexole is a synthetic amino-benzothiazole and the (+)-enantiomer of pramipexole which has dopaminergic activity and is a mitochondrial neuroprotectant by scavenging reactive oxygen and nitrogen species (RONS) (Cheah & Kiernan, 2010; Gribkoff & Bozik, 2008).

In earlier studies, RPPX reduced oxidative stress in sporadic ALS patients (Pattee et al., 2003). RPPX has been found to be safe and tolerable (Bozik et al., 2010; Wang et al., 2008), but did not change ALSFRS-R (NCT00140218, NCT00600873, NCT00596115, NCT00647296) (Wang et al., 2008). In the open-label extension protocol, RPPX caused a non-significant reduction in the slope of decline in the ALSFRS-R score (NCT00931944) (Wang et al., 2008).

RPPX is currently evaluated in a phase III study (NCT01281189) in ALS patients.
