Almost certainly for hyperthyroid... so maybe you'll be bit a more somnolescent than usual... or maybe (much more likely?) the single dose will have absolutely no visible effect at all. Or maybe the toxic chemicals that contaminated the drug in India (but were ignored because it's only for cats) are killing your kidney cells as we speak and by Sunday you'll have turned a curious tinge of yellow. Uhm....actually, yesterday was pretty much a normal day....drank lots of milk, took some naps on a pile of fresh clothes, watched TV on my wife's lap, chased the other cats around, hit the box a few times....pretty much a typical day for me.
PA Crew members NEVER turned 'yellow' ;)