. Author manuscript; available in PMC: 2019 Apr 17.

Published in final edited form as: Nat Rev Neurol. 2018 Oct;14(10):590–605. doi: 10.1038/s41582-018-0051-6

Table 4 |.

Candidate symptomatic drugs for treatment of SCAs

SCA type	Candidate drug	Scientific premise	Preclinical study	Comments
SCA6 and other SCAs	4-Aminopyridine	Restoration of pacemaker activities of Purkinje cells by blocking the voltage- dependent family of potassium channels⁸⁷	Alleviated motor coordination deficits and restored Purkinje cell firing precision in SCA6 mice homozygous for 84 polyQ repeats⁸⁷	Approved by the FDA for symptomatic improvement of walking in multiple sclerosis. A randomized, double- blind, placebo- controlled study showed a decreased number of attacks in patients with episodic ataxia 2 (reF.²¹³). A phase I study²¹⁴ and a small open- label study²¹⁵ have been done in patients with SCAs
SCA2 and other SCAs	Chlorzoxazone	KCNN1 channel activator. Normalization of the Purkinje cell spontaneous firing rate in SCA2 transgenic mice with 58 polyQ repeats¹⁰⁰ and in Cacna1a- mutant mice⁹³	Not yet done	Chlorzoxazone is approved by the FDA and has been used extensively as a muscle relaxant
SCA44	Nitazoxanide	Negative allosteric modulator of metabotropic glutamate receptor 1 and 5 with potent inhibition of mutant forms of these receptors in transfected cells²¹⁴	Not done in SCA44 models, but similar modulators alleviated ataxia in an SCA1 mouse model^216,217	Nitazoxanide is approved by the FDA and is used for various helminthic, protozoal and viral infections²¹⁸

KCNN1, small-conductance calcium-activated potassium channel protein 1; polyQ, polyglutamine; SCA, spinocerebellar ataxia.