I bought mine online from Chewy with a script from the vet. It cost $152 for two vials, which might be too much for only one cat, since you can't use the vial for very long once it's opened (though my vet did say one can probably use it for a bit longer than what manufacturer recommends). I think Petco offers a single vial for $80, which seems like it would be more helpful. To give you an idea, Chewie was 11-ish pounds and used to get 0.23mL every dose (the regimen our vet followed was: 2 injections a week for 4 weeks, then 1 injection a week for 4 weeks, and as needed after that - for Chewie and Mew, it turned out to be needed once-weekly). It took a bit to build up but really helped them. You can use U-100 syringes instead of buying hypodermic syringes from the vet too. Works just fine.
With all that being said, I recently tried Adequan in prevention on Chewie's brother Wicket, who doesn't really suffer from any visible arthritis yet (but I know all senior cats have it to some degree so wanted to get ahead of it) and after each injection he's had several days of lethargy and very poor appetite. He does have chronic pancreatitis, but it happened three times, every time nothing had changed but his Adequan injection, so I think he's just one of those rare cats who gets weird side effects from it. Since Adequan is off-label in cats and it's difficult to pinpoint the cause of vague symptoms like poor appetite, it's very difficult to report such side effects to the manufacturer, which may contribute to the product's great safety profile?
Long story short, it's working great for my Mew, but I won't be giving any more of it to Wicket, and just wanted to include that like all drugs, it's not devoid of side effects.
