Approximately 150 subjects will be randomized in a 1:1 ratio to SST-0225 or placebo at up to three study centers in the US. Subject participation will be between 12 and 26 days depending on the length of the initial screening period. Once a subject is randomized the duration of participation will be 10 days. The expected duration of the study is approximately six months depending on enrollment. The sample size may be increased to a maximum of 250 based on the results of the planned interim analysis described in Section 15.2 of the protocol.