s(-)-cyanopindolol hemifumarate salt 4-[3-(tert-Butylamino)-2-hydroxypropoxy]-1H-indole-2-carbonitrile 4-{2-Hydroxy-3-[(2-methyl-2-propanyl)amino]propoxy}-1H-indole-2-c arbonitrile 4-[3-[(1,1-dimethylethyl)amino]-2-hydroxypropyl]-1h-indole-2-carbonitrile hemifumarate salt