Safety, tolerability, and pharmacokinetics of KNS-760704 (dexpramipexole) in healthy adult subjects.

Dexpramipexole (KNS-760704; [6R]-4,5,6,7-tetrahydro-N6-propyl-2,6-benzothiazole-diamine) is a novel synthetic amino-benzothiazole in development for the treatment of amyotrophic lateral sclerosis (ALS). Preclinical studies have shown that dexpramipexole is neuroprotective in vitro and in vivo, is highly orally bioavailable and water soluble, and rapidly achieves and maintains high central nervous system concentrations relative to plasma. Two phase 1 clinical studies were conducted to assess the safety, tolerability, and pharmacokinetics (PK) of single and multiple doses of dexpramipexole in 54 healthy male and female adults. The effect of food on the single-dose PK of dexpramipexole was also evaluated. Single doses (50 mg, 150 mg, or 300 mg) and multiple doses (50 mg twice daily, 100 mg twice daily, or 150 mg twice daily) of dexpramipexole over 4.5 days were safe and well tolerated. Dexpramipexole was rapidly absorbed, with time to maximum plasma concentration ranging from 1.8 to 2.6 hours and half-life ranging from 6.4 to 8.1 hours under fasted conditions, and was mostly eliminated in urine as unchanged parent drug (84%-90% of dose). Food had no effect on the single-dose PK of dexpramipexole. These findings support the ongoing development of dexpramipexole for the treatment of ALS and further evaluation of the compound's therapeutic potential in other neurodegenerative diseases.