A photograph of pure<unk>  HCl powder.<unk>  is a pyrazinoylguanidine, composed of a substituted pyrazine ring structure with a carbonylguanidinium substituent.<unk> 's pKa is 8.67, which is due to the guanidinium group. In high pH (alkaline, low hydrogen concentration) environments, the guanidinium group is deprotonated and the compound is rendered neutral, depleting its activity on sodium channels.<unk> , as a pure substance, is highly fluorescent, with excitation wavelengths at 215, 288, and 360 nm, emitting light at 420 nm. Light at wavelength 420nm. This is the emission wavelength for light due to<unk>  fluorescence.
Amiloride
Bumetanide
Chlorothiazide
Furosemide
Cyclothiazide
Tolvaptan
Torasemide
Spironolactone