Viagra (sildenafil citrate or more accurately 1-[[3-(6,7-dihydro-1-methyl-7-oxo-3-propyl-1H-pyrazolo[4,3-d]pyrimidin-5-yl)-4-ethoxyphenyl]sulfonyl]-4-methylpiperazine citrate) is an off-white crystaline powder not a solvent so it won't dissolve anything.
Perhaps it's just a way of making it easier to swallow. Sorry FIRE5149 not sure if it's soluble. I've dissolved pain killers and other tablets before but have no experience with viagra.
I'm assuming that because of the cost you don't want to experiment with dissolving one?
Erm, sorry for flogging this to death but IT IS SOLUBLE a 25 mg tablet will dissolve in only 7.2 mL of water. If you consider a shot from an optic is 25 mL then you could get at least 3x 25 mg tablets to dissolve per shot volume.